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Dragon Con: Prep, Ready, and Deploy

September 8, 2012, 8:23 pm
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Every year, my friends and I bring a plethora of robots to compete at Dragon Con's Robot Battles competition. It includes 1 and 3 pound robots for their Microbattles segment on Sunday, and 12 and 30 pound sumo robots for their main event on Monday.

As tradition, out entries must consist of several "assbots" among our serious entries.

Wheel! (Colson Bot)
After four years of being relatively invincible, I have decided to force-retire DDT. Replacing it at Dragon Con will be the beloved assbot dubbed "Colson Bot".

In the mid-2000's, the arena hazard for micro battles was a colson wheel attached to the output of an angle grinder. It was well known for its overpowering hits that often determined the outcome of the matches. Colson Bot was designed to look and function very similarly... without the stability of being bolted to the ground.

Being an assbot, I had determined that the budget would be minimal. Luckily I had just disassembled DDT and Prop Quiz which left me with several options for controllers and motors. I elected to recycle the gearmotors from Prop Quiz and the electronics from DDT.

There were two main steps to the design: finding a colson that could be bored large enough to fit the electronics and making a chassis small enough to fit in that bore. Given I had already selected my parts, I decided to reverse order design and build the chassis first.


Treads would have been ideal to maximize traction, but could not be done with the space constraint. Instead, the design used is pictured above. The robot is designed in layers. The bottom layer (including the wedge) is 3D printed out of PLA on one of the Invention Studio Ultimakers. The top section is waterjetted polycarbonate screwed on from the bottom of the robot. This top section mounts the Esskay 400xt brushless motor that directly drives the colson wheel (not pictured). I fully expect the 3D printed chassis to snap somewhere.

Colson Bot went together very quickly. I had only 8 holes to countersink and a few things to wire.


...and functionality tests.




Quick enough certainly. I'm dissatisfied with the acceleration of the robot, but once again I play the "apathy via assbot" rule. I have also yet to achieve maximum speed. the robot lifts off and goes unstable before I can spin it high enough. Although the esc braking function provides an interesting way to escape bad situations.


After a quick paint job, lets call it complete.

Dominant Mode
Clash of the Bots 3 showed me a few aspects of the robot that were not ideal:
  • The unreliability of Spektrum technology
  • The ineffectiveness of UHMW anti-wedge slips
  • Something resulting in periodic signal loss
  • Custom brushless drum subject to axial shifts
For now, we will waive off the Spektrum issue since it seem to have corrected itself somehow. The anti-wedge slips will be replaced by a few alternatives. 


I drew up this design awhile back. It uses a set of Titanium forks to get under opponents. I favorite this design because it leaves nice sharp points to get under wedges and are not dependent on the position of the other wedge tips. This is a good feature to have in case part of the wedge incurs damage; the other fine points will not be affected.

Others have recommended that I simply bend some blue-tempered spring steel. Since one option was clearly easier than other other, I decide to try waterjet machining some of the 0.01" spring steel stock I had bought for Razor Reloaded.

To prevent the drum shifting, I laser cut a thin ring of acrylic. This will keep the outer bearing from shifting off the mount. For Robot Battles, this should be fine as long as I don't fight and horizontal spinners. For future competitions, I will probably upgrade to a more ductile material like polycarbonate or polyethylene. 

In previous experience with Cake, my first explanations to the radio cutoff was a short between the ground and +5V lines somewhere in the receiver. For Cake, this would usually occur around the drum shaft, where the drum shaft ID would eat through the insulation and contact the PWM wires. For Dominant Mode, no such symptom was to be seen since all the electronics were contained within the body this time. I though perhaps the motor windings were shorting somewhere again, but drive independent tests confirmed otherwise. What ended up being the concluded culprit was the receiver. I had Adam Bercu of Busted Nut Robotics pick up a Spektrum AR6115e on his way down to Atlanta, which solved the problems.

Turboencabulator
What in the world is a turboencabulator? Few people know, but it sounds pretty complicated even though the only new principle involved is power production from the modial interaction of magneto-reluctance and capacitive directance. 

It is a sub-ass bot designed to go fast. I want it to be good yet require minimal spending on my part so many of the parts will be recycled from random things. The basic idea was to create a sturdy 4-wheel drive base and incorporate some simple active weapon on it. 

I was originally intending on using some 860-sized Johnson motors on some 5:1 gearboxes I had, but I would only be able to use two of them and 4-wheel drive with chain would have become costly very quickly. Instead I opted for some low RPM (high kt) 540-sized motors from surplus center. These guys put out a whopping 62 oz-in/amp! Combined with the 5:1 gearboxes on 3" wheels, I could move 24lbs while only drawing 16 Amps continuous. Sounded like an ideal duty for my Banebots 12-45 ESCs that havent seen action since 2008.



The 5:1 gearboxes were salvaged from the Hitachi copier motors that we previously purchased for stator grabs. We had maybe 6-7 of them on hand and since they included bearings it was idea for a low cost solution. Pinions were made from the motor-side shafting by rough cutting them to length, facing them, and then boring them on the lathe. The arbor press finished the installation process.


The 30A Mcmaster bots wheels were pressed directly on the shaft of the output gears. This assembly was suspended in between two frame rails made of HDPE (for now). 


From there, the robot quickly went together.

The Turboencabulator sans roller weapon.



However, did not fair well in some sparring.


The Carly Rae Jepsen Wallbanger puts a nice one into Turbo's side.


The hit actually smashed in a roller motor and deformed the HDPE enough to cause plastic deformation. So the robot was upgraded with steel outer panels thanks to Adam once again.

Intermisssion: Other happenings during the Dragon Con prop week.
Fun things to do with 30 pound combat robots:


The MIT crew bought over 14 power tools from Harbor Freight to hack into robot drives.

Greg bot (Critical Space Item). It has the drive train of a 12 pound robot.

Competition: Sunday
There wasn't much to say about Micro battles because the competition did not last long. It was originally a double elimination tournament but due to the record number of competitors and truncated time allotment for the ballroom, they decided to switch tournament types mid-way through.

Dominant had only one opponent before driving through the pit. Here is the footage.





Turns out the hotter wound motor is too fast. With the spring steel wedglets gripping the floor, I couldn't get enough ground speed to bite into the opponent. The first match shows robot milling while the second match shows more effective biting from 30% throttle.

The second match also shows why I should stop trying to push opponents into the pit. Fail.

Colson bot did not receive the same recognition as I had expected because the EO was rushing. Here is the result.



Without an e-clip on the motor, the top comes off and splays itself around the arena.

Competition: Monday
Arrived nice and early to talk jabber with the other builders.


Turbo was ready to go, fully charged and sporting its new A-36 side plates. It weighed 11.5 lbs.



Our friends from the north were already there with a beautiful array of 30 pound robots.


Dale Heatherington brought the competition's first fully autonomous robot, Scary-Go-Round. It is able to track the opponent and stage boundaries while constantly rotating. Quite an amazing robot.

Turbo had the first match of the competition against a solid block robot named Ice Cube.






The rollers worked perfectly! Between the higher RPM 2" colsons and the 3" mcmaster bot wheels for drive, I was able to "dribble" my opponent on top of my robot for the perfect delivery. Match 1-3 was a great display of control over the opponent.

Unfortunately, match 2 was not as lucky. I was pitted against a robot named Tilla the Hun, which used a very similar principle to turn over other bots.


He had wire brushes for wheels which gave him superior traction on the carpeted surface. I though perhaps my ramming mass alone could push him back but he had superior traction.

For the rest of the competition, I aided with Charles' and Adam's robots since they had some major repairs between matches. One of which resulted in Uberclocker Ubershanker.


That is my $15 katana strapped to the clamping arm of Uberclocker to try and compensate for its broken lifter spatula. It actually worked vs a match against Pinball, as it lodged perfectly in between the body and top plate.

Turbo's final appearance was in the 12 pound rumble where it once again showed its ability. Because Michael Jeffries of Near Chaos Robotics swept both events, I was gunning for him but Apollyon's quick drive train kept it a chase the entire time.



Conculsions
Overall, the competition was a personal fail considering my experience but it was a nice change of pace. I was able to experience the relaxing end of robot combat with the best seats in the house (backstage). I'll be thinking about new designs for future competitions. The next competition believe is the Atlanta Mini Maker Faire (October 6th) and Chattanooga Robot Battles.

I'm dreaming of a 12-pound Uberclocker...
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AMMF: It's Robot Fighting Time!

October 20, 2012, 6:41 pm
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Robots. One week ago, the second annual Atlanta Mini Maker Faire held its first ever robotic combat event primarily organized by yours truly. It seemed like an opportune time to feature destructive machines given the audience and zany maker atmosphere.

What made this event particularly interesting (other than the fact that I tried to organize it while fighting pneumonia) was the experimental team battle format. An exerpt describing the function of the team rules is described below:
_________________________________________________________________________________

The competition shall be composed of two sets of rounds:
  1. Qualifying Rounds
  2.  Elimination Rounds

Qualifying Rounds
Each match will consist of 4 entrants in a 2v2 format. The alliances per match are random. The winners of the bout are declared when both entrants of the opposing team are incapacitated, unable to display controlled translational movement, or are ejected from the arena. Match length will be 3 minutes. If any number of devices on each team are in the arena and still able to display controlled translational movement, the winner will be decided by a judge’s decision.
At the conclusion of each match, points will be awarded to each robot.
  • 2 points for both the robots on the winning team*
  • 1 point for each robot remaining in the arena

*0 points will be awarded to robots that do not attend their designated match time.*

Robots with byes will be compensated with 2 points.

At a specified time designated by the event organizer, the points for each robot will be tallied and the top 4 devices will advance to the Elimination Rounds.

Elimination Rounds
The winners of each match in the elimination round will be determined using the standard 2011 RFL ruleset.
The remaining 4 robots will engage in single-elimination, 1v1 combat beginning with the semi-final round.
The winners of each semi-finals round will advance to a finals round, where the bracket winner will be determined.

_________________________________________________________________________________

This new format is advantageous because it allows robots to maximize the number of matches they fights in a more condensed time period. However there may be possible conflicts regarding the recharge time typically allotted after each match. This value, of typically 20 minutes, would then drive the frequency of the matches, especially for events with a sparse number of robots. The main negative to this format is the amount of pre-planning required. Walk-up registration is difficult to plan given that most of the match organization is currently done by hand. This would require pre-registration unless an algorithm is used.

For the AMMF, we had 12 robots by the time registration was done; that is, 6 ants and 6 beetles. Michael Jeffries of Near Chaos Robotics assembled the match line up with some quick wit. The idea for the AMMF was to attempt to allow the builders to see the attractions of the faire by hosting matches at preset times during the hour. In the case of this event, every half hour. However, given the low number of robots, it meant that competitors at best case would have a max of 1 or 1.5 hours to look around assuming they don't have robots in both weight classes.

I decided not to enter any of robots directly since I believe the EO should never win their own event.

Cool trophies for the winners of each weight class and rumble.




These were simply laser cut acrylic pieces that were pressed together and then welded using acrylic solvents.

We were placed at the base of the stairs between the CULC and Skiles buildings. It was nice and shady, and the stairs offered free seating for the crowd.



The stands were quickly populated by makers and crowd alike.





I was honestly surprised at the number of attendees. The competition was assembled rather late and not actively publicized yet we had massive waves of viewers throughout the day. Equally impressive were the robots.

The Hammer, one of many robots built at the Invention Studio.

Beetleweights engaged in a qualifiers match.

One team preys on the other team.
The best part of the team format is that no matches were particularly boring. There was always at least one spinner which made from a lot of excitement. Some of the most notable matches at embedded below.










By the end, I decided to have some fun too and threw Dominant Mode in the beetleweight rumble. I'm not supposed to win my own rumble.



More videos can be found at the Near Chaos Robotics Youtube Channel. 

Mow Bot, the beetleweight champion of the event.
With that, I'll call the event a success. The team format was proven to be a big hit, although I think more has to be done in consideration of the builders. This format is great for the audience but the time between cycles on robots is incredibly small. This left very little time for other builders to see other exhibits. In a normal competition where robot combat is the main event, this might not be as large a problem. Still, it might require back to back matches or lessened recharge time. This implies that the team format is best done with a large number of competitors.

Huge thanks to the competitors and members of the robot community who helped set up. This means Randy, Rob, Mike, and several others who not only helped setup brackets, but unload the arena and bring robots so we can have a good show. You guys made this happen!

'Till next time, BOT ON!
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GMX Part 1: Preparation

October 28, 2012, 10:16 am
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Those who have seen the beetleweight rumble from the AMMF event will remember that Dominant Mode's drive began failing at the end. With GMX on October 26th, it was time to investigate the source of these issues.

oops

That doesn't look healthy. The cylindrical shaped piece on the table is the front bushing for the KW motor, which had fallen out in all the excitement. It was accompanied by a nice layer of brass pinion dust as it seems to have evaporated in the misalignment. 

I determined that the main faults of this mod were the improper mating of the KW motor to the 280's face plate mount and the inadequate length of shaft used to secure the brass pinion. Because the stock face plate was not intended to mate to these motors, it allowed all sorts of slop in the alignment of the gears. To reach the first cluster gear, the pinion had to be mounted on the tip of the KW motor since the KW motor shaft was sufficiently shorter than the 280's. This meant there was a poor friction connection between the motor and the pinion, and an even worse connection between the pinion and its first cluster gear. No amount of JB Weld could remedy the situation. 

The solution was the remake the motor face plate. This new version would need to have features to properly made the motor concentrically to the gearbox and bring the motor shaft closer to the first cluster gear. I found that a simple flat of 1/8" aluminum was sufficient. 


I made several mistake in the model, but I had the main bolt pattern correct so I was able to match drill the new piece.


The full length of the pinion is now available for contact despite being pressed fully onto the shaft. This was complimented with JB Weld. The internal shafts in the gearbox did stick out the back of the new face plate so the entire end was belt sanded to make that surface flush. For the record, the main two screws that bolt through the gearbox are M2.5 and the pins are 2mm dia. I will make this face plate available as soon as I develop a proper model.


The gearbox and resulting combination. Because I couldn't find the loctite, I opted to JB Weld everything. Hopefully, its insane bonding power will be sufficient for holding screws.

Meanwhile, I have been planning a new antweight in light of Dragon Con Robot Battles. Colson Bot was fun, but not entertaining enough for my tastes. It was time to revive the champion of entertainment: DDT.

This time around, the goals were to increase the rigidity of the frame and ease manufacturing. For me, this basically meant waterjet, waterjet, waterjet.



The main idea was to waterjet two slabs of UHMW and stack them together to compose the main frame. The weight for this upgrade would come from a smaller battery and smaller drive motors. The banebots 24:1 gearmotors were overkill for moving an antweight. Instead I opted for the brass micro gearmotors found at pololu. These would be belted to two dead shafts holding the drive wheels. This drive assembly would be mounted to 1/8" 6061 aluminum plates to keep everything in alignment; I wouldn't trust UHMW to stay rigid enough.


The newest version sunk these plates into the UHMW sides. While the disk remained the same, the weapon was upgraded to a Hacker A20-20L. Similarly, the battery was decreased to 460 mAh, but increased voltage to 11.1 V. This meant approximately 11 kRPMs!


The frame was waterjet with through holes for alignment. First some small nails were inserted to keep it together. Then the side plates could be pressed in and drilled. This assisted in assembly of the rest of the machine. 



Drive module. Those are M1.6 cap screws that go through the front plate of the pololu gearmotors. The dead shaft is 1/4" delrin for the time being.


DDT's frame quickly coming together! Top plates are made from 5XXX anodized aluminum for the purpose of engraving logos later.


The belt system for the drive. The motor side pulley is 1/2" OD for a 3/32" urethane belt. The wheel side has a 5/8" OD and is made of delrin. To simplify the assembly, I am using the bearing properties of delrin instead of opting for bearings or bushings.


When I had first purchased the new lite flite wheels for the robot, I had planned on using larger 2.5" diameter  wheels. Now that I inspect the design, it would must better benefit from smaller wheels. With only 2 days before the competition, I decided to try turning neoprene rubber. I shoved a 1/2" aluminum shaft into the inner diameter of the foam wheels and placed them side by side on my lathe. I spun them at 755 RPM and made .03" passes with a sharp carbide bit. It was messy but returned great results.


The top cover after engraving. Included is the molecule so others can make the connection. DDT the pesticide, killing the antweight robots.





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GMX Part 2: Combat!

December 9, 2012, 8:43 pm
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On Friday evening we hadn't left Atlanta until maybe 10 or 11 because SOME PEOPLE were beast-mode machining their robots. Piled into two cars and drove up to Nashville some 4-5 hours later.

The next morning we rolled out of bed to the hotel and set up for the Geek Media Expo's second annual Robot Battled event, or Robot Battles 45 if you'll have it. As we entered, the arena provided by Thomas Kenny was being set up. It was a smaller 4 x 4' arena with a pushout. I was slightly worried about DDT's spin-up time and bouncing but it definitely favored Dominant Mode who operates very well in tight conditions.

Empty for now...
...busy the rest of the day

The Georgia Tech crew brought several robots. We had two antweights between Jim and myself, and six beetleweights created by Gabe Ochoa, Dan Hammer, Xo Wang, Aaron fan, Greg (who wasn't actually there), and myself. 
GT crew and the compound table.

 There ended up being two other antweights, and 2 other beetleweights. Therefore the ants ran double round robin and the beetles ran double elimination. Needless to say, Georgia Tech was over half the competition.

Robots preparing. Everyone looks nice and undamaged right now.

Jim Shealy adds tape to the base of Quantum Platypus to dampen the other spinners.

Dan Hammer working on "The hammer"

Gabe Ochoa, the builder of Mowbot, adding the final preparations.

Mowbot, the champion of the AMMF Robot Battles, sporting a new frame and blade.

Quantum Platypus, the enormous overhead disk spinner.

Gyro King, the massive melty bot made by Aaron Fan and Xo Wang.

My things. Last minute polycarbonate anti-wedge additions being made.

______________________________________________________________________________

DDT vs Quantum Platypus.
DDT pulled the first match of the competition against fellow GT builder Jim Shealy. QP had a nasty overhead hardened A2/plastic composite disk and a wide polycarbonate base for stability and entrapment. Most other robots would have met their doom, but luckily enough DDT's front disk was large and low enough to barely evade the tips of those bars. This is also the first time I have run DDT -_-

DDT proved to have no problem with weapon power. Instant spin up time and enough power to keep it bouncing around the arena. This is not quite compensation for its inability to drive inverted, but it certainly helps. Quantum Platypus's foam adhesives worked well at first, but when DDT struck frame things began to fall apart. DDT wins by JD.

I feel bad for destroying the floor.

Dominant Mode vs Gyro King
Dang! First beetle match of the morning is going to be a big one. Gyro King is a melty brain robot with large 35mm brushless motors for wheels and a solid aluminum frame waterjet from a single billet of 1.5" aluminum. To add to its impressiveness, its motor controllers and bluetooth communications were custom made AND it has hardened s7 teeth. Dominant Mode's drum was rather soft 4130 so I was anticipating the worst. My initial strategy was to box rush, but it doesn't always work out as planned.


Dom takes a nice bite from the tooth support after removing the S7 teeth.
Gyro King was having trouble spinning up. It was designed to spin to over 6000 RPMs but was only getting about 2000. Had it been up to full power it might have been far worse for me considering the number of missed rushes. But Dom removed the S7 teeth by shearing the bolts and nearly ejected Gyro King from the arena. The hit jarred the HDPE dead weights in the robot and high centered its drive wheels. Dom wins by KO.

DDT vs Hardboiled
Return to the antweights to fight last year's winner of GMX Robot Battles. Hardboiled was a fast wedge that didn't show and visible weaknesses. A good driver and reliable drive train was enough for it to clench its first round victory against Green Reaper so I expected him to keep on DDT such that I could not spin up. We would see how well the disk spin up time would be now.


Seems more than sufficient. Even under load, I could torque the disk and spin both robots apart. This bodes very well for DDT seeing as how disk spin up has plagued the old version. DDT wins with an odd flipping slice.

DDT ended up fighting Hardboiled twice more for the round robin format and the championship. All the matches had similar outcomes with equal or greater amounts of bouncing. DDT ends up victorious in both cases. 

Dominant Mode vs Gregbot
Gregbot (or Critical Space Item if you prefer) is a creation of Greg Shikman from Cooper Union. We still have his robot from Dragon Con for whatever reason, and allowed us to run it for GMX. Well, it won its first match against The Hammer and now comes to fight Dominant mode. Gregbot has an overpowered drive train sufficient for 12-pound robots and has an unfathomable translation speed. Gregbot has the potential to really boss Dom around if only it was controllable >_>


Gregbot ended up flipping early from hitting the wall with its springy steel frame. From then on, it was pretty much over. 

Dominant Mode vs Spiky Turtle Screwy Thing
I don't remember the name of this robot exactly, but it was driven by a bright young fellow with a lot of potential. The robot's body was a inverted cake pan and had all sorts of screws sticking out of it as a defense.


I tried my best to not destroy it so I flipped it once and pushed it out. The humane kill for the trutle:)

Dominant Mode vs Mowbot (Finals!)
Finals time! Mowbot suffered some pre-competition damage and was reduced to a pushy bot with a reliable drivetrain. In its last match against Gyro King it suffered a battery short as it was exiting the arena had to be escorted out of the hotel in a fiery bucket. But no harm done, Mowbot was back in action in no time despite looking a bit like it was slapped with baby powder.


Gabe and I both knew that we would lock in a pushy match if we went head on because his front and rear wedges were angled to avoid the drum but contact the frame first. I would try and avoid a head on confrontation like that and instead aim for his corners.

When the match began, he had me where I didn't want to be: pinned against the wall after head-on contact. However when he backed up, I struck the front corner which opened up his front panel and exposed his battery.


After a brief pause we decided to go pushy bots for the rest of the match. The crowd cheered for good sportsmanship and more robot fighting. However the first charge by both robots was the killing blow. Mowbot darted past Dom with its battery hanging out and Dom tagged the trailing battery, pulling it out of its connector. Dom wins in a hilarious final moment. 

Antweight Rumble
At the conclusion of the antweight bracket, we held a small rumble with the three remaining robots in the antweight class.


It turned into a robot dance-off with DDT suggesting its name should be DDR.

Beetleweight Rumble
Two words: Pure. Chaos. Dan and I had agreed to hit weapon to weapon but it seemed like Thomas wanted some action first. By the time Dan and I had any sort of contact, Dom was missing some screws on the side plates. Then, I missed his weapon and fed him my weakened side...


Dominant Mode has never had that much damage before. Both sides incompacitated and a drum bearing shattered. It turns out Dan's robot (The Hammer) pierced through the Ti around the front cap and pulled the entire assembly out. I later gave him those parts as a trophy.

The drum sounded like maracas because of the loose balls inside.

Boom.


Dan Hammer's trophy from me.


Conclusions
Both robots did well but its clear that that Dom needs work. The frame is still vulnerable to horizontal spinners regardless of the angled sides. The inner rails were also tweaked and bent so there needs to be more work in stiffening the front portions of the frame.


The entire competition was pretty rushed for the competitors because of the low number of robots. However, spare batteries and maybe six chargers kept us all going. Given the excitement of the group, I have no doubts we will return to GMX and Robot Battles again!

Big thanks to Xo Wang and Dan Hammer for the excellent video captures! Also thanks to Thomas, GMX, and the MTRAS crew for a great event! On behalf of the Georgia Tech crew, we thank you for a wonderful time!
________________________________________________________________________________

Other awesome moments of the event.
The Hammer vs Gregbot (grudge match)


The Hammer vs Gyro King


Also, the mini highlight reel
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Xbox 360 Power Supply Hack

December 17, 2012, 2:55 am
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My most recent scooter (that I built and haven't yet blogged about) uses a 7s2p Lithium Iron Phosphate pack using A123 cells. That is great except my Triton EQ charger can only handle 6s Lithium anything. The obvious solution was to purchase new charging equipment like this beautiful Turnigy 8s charger capable of 7A continuous. However, it also means I need to find a suitable power supply that can output at least 4.6A at ~23.1V with an input range of 11 to 15V.

That last requirement removes most laptop power supplies from the list of hopefuls. But, it does shine some light on my favorite gaming platform, the Xbox 360. The 360 variants feature external power supplies with some funky 8 pin output cable. Furthermore there are variants that output some 135W (Xbox 360 Slim) to 203W (Xbox 360 original console) of power. My favorite part about these power supplies is they can be obtained for cheap because they are available everywhere. I grabbed a 150W variant off ebay for $18 free shipping.

Alright! Hacking time! I received my box and noted many familiar items. Wall plug, power brick, lalala... oh wait.

8 pins wtf

What the hell is this? Some 8-pin output connector that goes into the Xbox. No clear labeling on the outside to signify the purpose of the pins.

It turns out, six of the pins are used for power transmission and two are used for a "standby" state. This is probably the minimum power required for the sleeping state on the Xbox (I mean how else do you turn it on using the wireless controllers?). Here is the pinout:

Courtesy of that website. Kudos go to them.
If you were to probe the outputs with a multimeter, you will find a 0V potential between the yellow and black UNTIL you supply the PWR_ENABLE pin with +5V. We are going to simply take the +5V USB line (RED) and connect it to the PWR_ENABLE permanently. Then we will connect the yellow and black wires together in parallel because I don't feel like 22ga PVC jacket wire is ever going to safety transmit 150W.

Anyway, I unplugged the charger cord, and immediately sliced into the cable behind the connector. Conveniently enough, the cables are colored accordingly.

8 pins, 8 wires. Life is good.

Strip away more wire and begin soldering things together. Three BLACK in paralle, three YELLOW in parallel, and connect the BLUE and RED/PURPLE.


Your choice on the shrink wrap and external connector. A good choice might be a power strip in case you want to power multiple items with it. Since this power supply is single duty, I soldered in an XT60 connector used for hobby RC.

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The Long Awaited

May 7, 2013, 3:04 pm
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I fully realize that I have not posted anything new (despite there being absolutely awesome things happening!) since Fall 2012. That is because I was busy. However, I did that thing called graduating and now have oodles of time to back-blog all the good stuff.

Everyone awaits they day they graduate. I've been hearing it from my peers for the past 4 months, accompanied by tears of joy, tears of sadness, and senioritis. The part of graduating I was anticipating the most was actually commencement ceremony. Not because of the symbolism when walking across the stage, or moving the tassel, but because there were large groups of people present. Time to do something awesome in my last hurrah: Decorate my graduation cap.

The original plan was to illuminate a piece of acrylic from the side using RGB LED strips. An arduino nano or equivalent uProcessor would control the transitions between the colors. All of this would be powered by one of my numerous 3s lithium polymer batteries. However, I was lazy with the parts ordering. So here is the final instructable on how to make this guy.

Parts:



Step 1: Design the acrylic cutout
I designed it using SolidWorks. Began with the diamond shape and then extruded-cut the letters. The logo was generated from importing an image and projecting it onto the background. Using the Spline tools I could trace the more complex geometry.


The material selected was acyrlic. This was because it had excellent optical properties and could be laser cut using the machines at the Georgia Tech Invention Studio. 


Step 2: Cut chamfers into the polycarbonate at the bend points
The most important thing to remember about this is to have enough allowance in the bend. I'm not going to discuss k-factors here, but cut away some extra material to allow the corners to meet without stressing the sides of the U. Do not just remove material along the theoretical permissible lines.



Step 3: Apply LED strip to the inside of the U-channel
The LED strip I linked too earlier has an adhesive back. This made it much easier to stick to the inside of the channel. Also, I believe the width of this strip is 6mm. Should interface perfectly with the mcmaster part number I also linked earlier.



Step 4: Bind the ends of the U-channel to encapsulate the acrylic cutout


Step 5: Attach to grad cap (hobbyking brand superglue!)
The acyrlic plate actually levitates within the constraints of the polycarb U-channel. If I wanted to reuse these materials, I could unfurl the polycarb channel and simply take everything out...



Step 6: Solder wires and connectors
I recommend adding connectors on both ends of the power switch. One plug will be for your battery, the other allows you to take the cap off without having to extract all your electronic guts. I may update this step to include my wiring harness.



Step 7: Graduate!

The cap was well received by everyone (except the fire marshall). As a result, I received lots of air time that afternoon.

From the GT camera crew there:




... and  the Atlanta Journal Constitution.

What a way to cap off the end of a four year adventure. Thank you friends for all the wonderful experiences. I dedicate this work to remember all of you.

Some Responses from non-GT folk:


":OOOOOOOOOOOOOOOO
i want to sex you in the most non gay fashino possible
so one of us has to be in cosplay"


lol...

The next step for me is the legendary MIT!
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Beyond Unboxing: Chinese E-bike Controller (chatparts.ltd)

May 8, 2013, 1:02 pm
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This post is a preliminary to a much more comprehensive post detailing controller capability that will be made when I am nearby more legit diagnostic equipment. For now, this post will contain my conclusions from observation, use, and light modification.

The "Beyond Unboxing" series is inspired by Charles Guan's posts concerning these same type of escs.

The Thing:
I have purchased a marketed 24V, 250W brushless controller for e-bikes hopefully as a replacement for Jasontrollers. What caught my eye was the cheaper shipping, faster delivery time, and the seller whose English was grammatically correct. It arrived just yesterday and after some observations, I am very excited about this controller.


The seller even included pre-stripped connectors!


Its casing was a interesting trapezoidal feature. Still a single tube of extruded aluminum, still two silicon pads on either end captured by two stainless steel brackets. I even think they used the same screws...

The chatparts esc also has fewer wires. The seller includes a diagram of the connectors (without labeling the individual wires) but there are unfortunately more than 9 connectors on this controller.


In short, it is incomplete. However the function can be deciphers from the connector ends since these are meant to be direct drop-ins for existing EV systems.

The Comparison:
Now lets have a closer look at a jason and chatpart side by side.


Its smaller... Less thick by about 1/8"


Board looks less janky. The chatparts ESC (bottom) has only SMT components whereas the jason (top) does not. I was also intrigued by the 7 labeled vias at the top left of the esc (in this picture, in this orientation). Those look like programming pins. It may be possible to reverse engineer the software and find out REALLY how this guy works.


Again, fewer wires.


Ah the processor! Everything in here is ST Mirco stuff.

MOSFETs:  STP75NF75
Processor:    STM8S903K3

Performance:
My test rig is just my latest GigaRazor scooter (that none of you know about yet) with a watt meter inline with the power source. Note that this is a sensorless configuration. I will not be able to conclude as to what functions it has but I can at least detail its behaviors.

Unmodified Test runs:

  • No-load behavior: Ramps up until near max throttle where controller experiences cutoff. Not choppy intermittent behavior, simply cuts-off. Repeatable behavior. However does not affect throttle behavior for subsequent runs. Lets consider this feature Controller Protection.
  • Load behavior: ~20 Amps current limit stock. Does not experience high speed cutoff under load (perhaps I am not traveling quick enough to reach no-load speeds). ESC is cool to the touch.


The controller was then modified using the solder-blob shunt method.

Modified Test Runs:

  • No-load behavior: Experiences intermittent cutoff at higher speeds. It is choppy, unlike the unmodified behavior before.
  • Load behavior: increased acceleration as expected. Choppy behavior as described in no-load experienced in load behavior. Watt meter reads ~50 Amps peak. Case is hot.


The controller shunt was then lowered to 40A and then 35A afterwards. The choppy behavior still persisted. I took this opportunity to measure to case surface temperature and discovered it was in excess of 120 degrees F AFTER a run at higher current.

My scooter uses an 8s3p A123 LiFePO4 pack and a Turnigy Areodrive SK3 6374-149 motor. This means at nominal voltage I should be rotating ~3933 RPMs. However at charged voltage I would be ~4172 RPMs. For comparable controllers in this application, it exceeds the infamous RPM limit determined by Charles and Shane years ago. To validate the RPM limit cutoff, I will test no-load conditions again using a 24V nominal battery or PSU.

Conclusions:
I will withhold my final judgement until I can more easily explain its behaviors and features. For now I can summarize the main takeaways:


  • Runs sensorless (sensored TBD although it has wires for it)
  • Possibly has high eRPM controller protection
  • Possibly has a second method of current limiting
  • Possibly has over temperature cutoff control
  • Smaller and cheaper than Jasontroller
  • No self-learn


More to come.
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Thrifty Roboting: The Vex Motor Controller 29

May 10, 2013, 5:59 pm
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The Vex Robotics Motor Controller 29 is quickly becoming the go-to esc for insect weight class robots. It offers a small form-factor single channel esc at a low cost of $10. Very minimal; no LEDs, current protection, or temperature protection.

Vexbox!

The website advertises 8.4V, 4A max. Roboteers know from experience that these little controllers can be pushed much higher. Some report running as high as 14.8V on some rather beefy 370 sized motors. this type of performance does not go without some minor electrical work.

The ambiguity arises in the minor modifications. Those who have never hacked about with analog servo boards may be unfamiliar with these methods. This post will provide a step-by step on how to hack your Vextrollers apart and will also conclude with a component level analysis and bench test to decipher their true capabilities.

Modifications:
Step 1: Deshelling the Casing
The enclosure is two halves of injection molded plastic with some drops of CA applied in the seams. To get the crab meat out, it is as simple as cracking the rather brittle superglue.

Stock OEM Vextroller

Apply a sharp knife to the corner and press in until the blade sits within the groove.

Applying Knife Edge to Vextroller Casing

Wiggle the knife until the casing begins to pry apart. Repeat this process for all four corners until the shell magically pops off.



Step 2: Modifying the Power Leads
The blackbox IO model of the Vextroller looks like this:



To get higher voltage input to the esc, we need to do some splicing. This is what we want in the end:



Cut the PWM male connector off, and separate the white, black, and red wires from each other.

PWM wires separated. Fourth Wire Created from the Leftovers


Then solder another black wire to GND (where there is already a black wire).

Black Wire Added to the Underside of the Board


You should now have 4 wires coming off of three pins. The white (signal) and one black (GND) wire will go to your receiver. The red (V_in) and other black (GND) will go towards your power source.

Done!


Step 3: Add Connectors and Protective Coatings
The last step is to add the appropriate connectors that mate to your devices. It is common to have the female PWM cables for the signal since most hobby receivers use male .1" spaced headers. I typically replace the motor connector with 2mm bullets or simply solder onto the motor ends. The entire esc can be covered in a tube of 3/4" OD heat shrink or potted with a rubberized glue. Completely up to you!

Here is a pair of Vextrollers installed in my Antweight, DDT. I used CA to bind two boards side-by-side and then used breadboard jumpers to connect the V_in and GND together. Because GND is also shared between inputs on the Rx, I only have three wires going to my receiver (expected four) and two wires headed to my power switch. The pair was afterwards wrapped in electrical tape and the leads will be potted in GOOP later.



Congratulations! You now have a simply-elegant insect-class esc. I have created a IGES solid model for the caseless Vextroller for those who wish to integrate it into their CAD. It can be downloaded below:

Download Link for Vextroller 29

NOTE: Since you will likely be using this controller with other components that supply power to your receiver (BEC) it is not necessary to add the fourth wire for the Rx GND. Instead, use the original three wires where V_in and GND are used for mains power and signal is the only wire going to the Rx. The device supplying BEC will provide GND connection. This technique will reduce ground loops, which are a major source of noise. In other words:



Parts Breakdown:
Here I have pictures of the top and bottom layout of the board. It can be seen there are some SMT resistors, a tantalum capacitor and some other devices. The main distinguishable components are listed below with datasheet if available.

Top of the Vex Robotics Motor Controller 29

Bottom of the Vex Robotics Motor Controller 29



  • Microcontroller:          PIC12F615
  • Gate Drivers:              301(?)
  • Half-Bridges:              FDS4935BZ (Fairchild), IRF8313PbF (International Rectifier)
  • Voltage Regulator:      2x(?)

Aaronbot3000 reports the voltage regulator is linear and outputs 4.5V

Based on these components, the Vextroller should be able to handle 30V and 6.9A continuous. these values are subject to change as more is learned about the gate driver capability and voltage regulator capability.

Performance:
Vextrollers will be tested for their maximum voltage ratings as well as their maximum current ratings through a no-load incremental voltage test and a constant voltage incremental load test. From these experiments we expect to detonate two Vextrollers but hope to determine a maximum wattage rating for robot use.

Known Motor-Voltage-Weight Class Pairings:
Pololu 50:1 - 11.1V - Antweight
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Gigarazor: The Practical Scooter (Backblogging)

May 18, 2013, 11:41 pm
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About 5-6 weeks ago, I bought one of these from a fellow Georgia Tech Student.

What is it? That is a fully functional Razor E300 electric scooter. I bought it with the intention of making it even MORE functional.



I was looking at Cambridge and Boston now. A larger campus with more bumps of sorts from historical sidewalks and roads. I was planning some seriously legit mods to Razor Reloaded (another scooter you dont know about) but opted for the premade sturdy steel frame foreseeing a busy time ahead of me for the final few weeks of the semester.

So what was the plan?

  • new motor
  • new batteries
  • proportional control
  • big switch
  • power consumption feedback
  • new controller
  • LEDs everywhere


I had bought a Turnigy Aerodrive SK3 6374-149 awhile back and decided it would be my motor choice.

After removing the old components, a motor mount was fashioned quickly from some 3/8" 7075 plate on the waterjet.




I had initially picked the Jasontroller as my brushless controller because my other graduating friend was selling his old equipment. Here is a unmodified no-load test from a bench top power supply.



The battery was comprised from generous donations from A123. This 8s3p pack shown below was bridged using copper mesh instead of copper braiding. I figured the equivalent copper cross section couldnt be any worse than the 12ga wire exiting the pack.



Completed and bundled. Yes, that is a DE9 female connector being used as a balance plug. It works wonderfully.



By this time I started riding it about campus. It did not have a main switch (on order from RMP) nor did it have a top plate. Regardless, it was hella fun.



Then came the top plate. Attempting to bend polycarbonate with a 40W heatgun...



...failing to bend polycarbonate with a heatgun.
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Cambridge and Guavascooter

June 6, 2013, 8:05 pm
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I made it alive to MIT. Today marks one week of life up here. One week of life walking about because my latest scooter  just came today. Discussing the name with Charles, we decided a more fitting name for it was "Guavascooter", as an extension of Melonscooter except using the guava sized SK3 motors.


Without delay, here comes testing.



Tonight I drove this route to MITERS from my temp housing at Tang. Its about 1.68 miles as indicated by the picture above.

This route expended 1967mAh of battery capacity. From a 6900mAh pack, this means I could run this route about three times safely assuming voltage drop does not fall below 21V (ESC cutoff).

Tomorrow, I will determine the max speed of this scooter via time trials down Vassar street. More to post later.

An additional note, I am no longer using the chatparts.ltd esc in Guavascooter. The current ESC is a elifebike esc, which Charles and I will touch on later in the coming weeks. Cheers!
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More Guavascooter: Speed and Distance Testing

June 8, 2013, 2:33 pm
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Today I took a little adventure to visit my good buddy Chris down over at Bolt IO, a new shiny hardware startup incubator located conveniently close to campus (and chinatown!). Needless to say, I'll be visiting often.

This trip, for this time anyway, included the use of the T, so I had to park my scooter somewhere on campus. When I returned, I visited the ME graduation banquet and then returned home for a bit. Later, I left my housing again for a meeting with my PI over in building 35. Nowhere throughout the day did I charge guavascooter. This was a perfect additional data point to hopefully better estimate traversal distance. Here is the route:



A total of 3.5 miles. using the numbers from last post, we expect a battery expenditure of about 1170 mAh per mile. However, today's route only used 3170 mAh, which means approximately 905 mAh were expended per mile. This results in a projected distance of 7.6 miles. Lets say 7 miles just to be safe.

The second test that day was the speed test. I selected the section of road between Amherst Alley and Mass Ave as the trial space. This is a roughly half-mile section of road.

My timer showed I made the trip in approximately 1 minute and 52 seconds. This meant that my scooter maxed out at about 16 miles per hour. That's pretty slow for my tastes considering Razor Wind was estimated to run at 30 miles per hour and Razor Reloaded was to run at ~25. This is not a major issue but if I decide to address it I could change the sprocket ratios or select a new motor.
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Cake Slice and PA Bot Blast 2013

July 25, 2013, 5:27 pm
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Hi Charles, I'm writing a blog post.

________________________________________________________________________________

Part of my joy of moving up to MIT was the fact that I was now in prime vicinity of a more lively roboting community. In the Northeast region, we have well established competitions like the Franklin Institute of Motorama.

Another regular event in Pennsylvania was PA Bot Blast, held in Bloomsburg every July. My friend Aaron fan from the Georgia Tech Invention Studio convinced me to go, so I convinced my long time bot buddy Charles Guan to make the trip with me. We created enough hoobaloo in MITERS to spawn a small team and soon we had an entire van committed to go. Hence fourth it was time to get prepared as the date loomed closer and closer.

DDT was definitely going. The new version was completed in late 2012 after Dragon Con in preparation for GMX robot battles where it went undefeated and unscathed. The only work I needed/wanted to do on him was trim the through bolts that hold the frame halves together. This way, the robot was actually invertable.

I hope heating those screws don't melt the nylocks

I was previously intending to bring Cake, my old Beetleweight made in 2010/2011, but I had lent it out to some friend going to Robogames and it returned to me... missing a few things.

Without a waterjet, there was no hopes of finishing the parts needed to make it competitive or solid. Time to move on.

Instead I opted to make a joke bot. Lets design a wedge with absolutely insane speed for the sole purpose of box rushing people and maybe decking them into the wall. No way it would win, but it would be extremely entertaining to watch and drive.

I grabbed a pair of 280-sized motors from my spares bin. These motors were surplus back from Florida but had some serious power. First indicator of this were EXTERNAL BRUSH HOUSINGS WITH HUGE CONTACTS. This is of course opposed to the dinky precious metal springs that daintily drape over the commutator. I knew this motor had some serious current carrying capabilities.

And they did. They drew 3 amps no load.

To make the robot a tad more reasonable I mated these motors to the 10:1 gearboxes of the ever popular "1000 RPM Gearmotors". First I had to remove the pinions from the old motors. Then I had to secure them to the new splined shafts of the surplus motors. Historically, we know that a press fit simply isnt enough for these motors since their monstrous torque essentially reams out the pinion if any excessive load is on the shaft (i.e. robot weight). I remedied the problem by complimenting the press with a flux and solder treatment.

With the drive motors finished, I began arranging the parts to develop a chassis design. While a traditional wedge could have worked, I felt it was to boring. Some creative arrangement later turned up an old friend of a robot: the dustpan.

3D printing frames is cheating

By this time, we only had two days left until the event. The only option was to 3D print the frame on the IDC's Dimension 1200es ABS FDM printer. It saved a lot of time on parts machining but it also introduced some headaches of its own along the way.

Robot taking shape! Control electronics were selected to hopefully run the powerful motors. I whipped out my 9 year old Scorpion HX esc for the drives, and pulled an orange RX for the control. It was then I discovered the esc was not enough to handle those surplus motor hacks. Sad day. I suppose we will have to compromise with a Pololu 4.41:1 HP gearmotor.

The wheels were leftover Banebots 40A durometer wheels with a hex bore. I made hubs from some metric hex stock center drilled for the 4mm motor shafts, drilled to hold a 6-32 set screw, and pressed into the BB wheels.

robut.

so far so good

To save some time on printing, I elected to make the dustpan bottom from a thin sheet of garolite. This sheet would be held on the bottom using adhesives.

It was decided that this robot, being made from parts of the robot cake, would refer to its inheritance in some way. Also being a wedge shape, I decided to name it Cake Slice. It would be a part (or slice if you prefer) of Cake, while having a slice-like shape. So brilliant, I know.

Apparently I don't have any finished photos :(

On the Friday evening two hours before our departure, I came home hoping to test drive the robot. Unfortunately I left my transmitter on and was unable to practice with the robot. Its first match would also serve as a driving test.
_______________________________________________________________________________

Game Day

Five hours of Miku later, we arrive at a waffle house and meet Aaron for a 4am meal. From there we venture down the last hour to the Columbia Mall in Bloomsburg to see the wonderful new arena that Jeremy and his parents had put up.

THIS IS IT. jk, test box

builders watching the robot being tested outside the test box

okay, the new arena seriously

omg prizes! best trophies in the US
Being the first builders that morning (we better have after camping out in the parking lot), we picked prime seating in a center row, right above a power outlet.

Aaron's robot ,"Final Exam" without hat

My two robots DDT and Cake Slice. Washers taped to the front to prevent wheelies

delran-bumble:a stepper motor drive robot from out MIT crew

threecoil: an innovative flywheel 4-bar flipper robot

Alex Hone's stuff
After a smooth check-in and drivers meeting, it was time to begin the fray. Leggo robots!
______________________________________________________________________________
DDT vs Slim Pickens
DDT drew the first match of the event against a sheet metal wedge. Slim was based off a viper kit if I recall correctly, and added some extra steel to strengthen the front plate from my horizontal blows. Unfortunately for him, DDT doesnt attack the body as much as he punishes the corners of any robot. DDT ripped and bent up the front wedge enough to high-center Slim and he tapped out.

Cake Slice vs TTI Wedge
Titan Tech Industries is developing a series of modular robot kits for interested persons. In this Bot Blast, they are debuting their wedge kit, which looks like a sloped Weta without an active weapon. By this, I mean a classic cheese wedge shape with UHMW wheel guards bend around the frame. My only concerns were CS's tendency to lift up when he charges the opponent. I would need to get a running start to keep the drive aggressive and the front end down.

What ended up happening was completely unexpected. I actually stripped the gears running around the box. When I opened them up, it appears the boxes were design to have about 1/5 gear face contact. Ugh. So terrible engineering. If you buy these ever, remember to remove some of the spacers on the intermediate stages to get better contact.

DDT vs Speed Bump
Nooooo! I have to fight one of our own :( Speed bump was a low wedge bot made from the donated frame of a fellow bot builder. It was less than an inch tall, and features a gaussian cross-section double wedge. The top was made of a plastic found in 3-ring binders and I was a bit afraid of blasting through it and hitting the lithium battery.

Luckily, there were no fires. The match was also far more difficult than I had imagined. The low angle of the wedge and the flexibility of the binder material made it early impossible to get a bite. My only good shots were the aluminum sides. After a few taps late into the match, Speedy was high-centered and tapped out.

Cake Slice vs Speed Bump
q.q

DDT vs Dust Pandemonium
Now I have to fight the style robot i was originally famous for: the dustpan. Pandemonium was a custom made CF almost-unibody with a meanacing thresher type weapon protruding from the front. He would charge opponents, capture them in the dustpan, and gnaw on their frames with the thresher. As long as I kept my blade out front, I knew I would be able to stay out of the pan and away from the weapon.

When the match began, he charged straight at me figuring he would not be able to maneuver around my blade. I hit straight into the gut of the dustpan and luckily hit a seam. That one hit penetrated into his electronics and gave me the fastest KO at 15 seconds.

Cake Slice vs Guildenstern

eep.

It appears layered ABS is easily ablated. No throwing hits though


DDT vs Ripto



DDT vs Ripto (finals)

Before the finals!

Unhappy bearing trying to escape

DDT and his spoils of war


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Peeling Up: An Up Mini Temperature Hack

February 4, 2014, 7:42 am
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Just purchased a 3D Printer for a certain special course that I am TA for this spring term. See below, its an Up Mini!



These guys had great reviews off the MAKE Magazine 3D Printer guide for 2014 and with a nominally low cost we were interested in making these become the primary workhorse of the course. The Form-1's and Mojo's may feel a bit sad.



There is a lot of good to say about this guy; nearly plug-and-play operation for Windows 8*, a superb software that considers the end user (except their ears), and a PCB print surface that enhances adhesion during the print but also facilitates easy removal after the job.



The one bad part is the warping for ABS materials. I made several calibration test prints and anything with gratuitous flat surface came up with nasty warping on one side. The Up Plus that my buddy Charles has never suffered from this issue and its hard to imagine that they downgraded between revisions.

Investigation showed the bed temperature was 60 deg C for both ABS and PLA. Two things strange about this. PLA doesn't need temperature stability to print well (especially on this perforated surface) and the bed temperature for ABS is half that of what other machines report as an ideal setting.



So how do I change it? In the Up Plus, the user could view the temperature settings under the "Maintenance" options. The bed temperature displays under the extruder temperature in the upper right of the window. However, when connected to the Up Mini the temperature option disappears! Stratasys holds a patent on heated enclosure systems, a feature that happens to be advertised by others when considering this machine. Is this Up's hilarious method of avoiding legal?

Okay, how about hardware fixes? I remove two screws and a ribbon cable to access the heated bed itself. The ribbon cable presumably connects to a heating element, the temperature sensor, etc...



NOPE. The bed is a routed circuit board resistive heater with a SINGLE component on it. Its not even a magical IC, its a single transistor. This engineer is good at saving money.



Investigation of this KSD-01F shows that a) it is native chinese and b) is nothing more than a temperature switch (thermostat). The controller pumps current into the board until it reaches a temperature threshold. Then the transistor shuts off and the board is assumed to maintain steady state as it switches on and off and temperature fluctuates about the cutoff. These thermostats appear to sell in a variety of different temperature cutoffs.



This is so ghetto, I decided to hack it. Using the Up Plus as the paragon of 3D printing, I set my target temperature to 100 deg C. I purchased a higher temperature model from amazon and soldered it onto the board in place of the old one.



As a simple test, I allowed the bed to preheat for and hour and began a print. The result was simply phenomenal. No warping at any section of the part. Subsequent prints of various size and shape also returned similar results.

 


 


Before you declare this a godsend and perform this on your printer consider this piece of heat transfer; the preheat is now absolutely necessary to achieve the higher bed temp. The printer has no feedback mechanism to monitor bed temp so if you hit "Print" the printer will not heat for longer to accommodate the higher temperature threshold; the heating cycle is likely hard-coded into the printer ROM which I do not yet know how to change. Also, given the printer dumps constant current into the bed means the input energy rate is constant; to achieve max temperature the time of heating needs to be increased. This assumes the ambient heat loss rate does not cause the bed temperature to reach steady state before the temperature threshold...

Later science posts regarding Up Mini:

  1. transient temperature profile for
  2. input current hack for heated bed (and temperature profile after)
  3. hack to lower or remove annoying buzzer
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Jayce: The Cosplay of Tomorrow (overdue) Version 1

March 27, 2014, 1:23 pm
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hicharleslookimmakingablogpostaboutthefammerfinallyareyouhappynow?
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Introduction

This guy:



is my favorite character in the popular online strategy game League of Legends. This is not because I like his mechanics, his character, or dashing good looks. Okay fine I like those too. But I loved the concept of the transforming hammer/cannon. This was directly in my line of 'thingsiliketocosplaywish' and so I embarked on the ambitious task of building the Mercury Hammer/Cannon for a Debonair Jayce Cosplay (Debonair is one of his skins, or appearance modified options).

Analysis

The weapon has two forms: the hammer and the cannon. Pictures below:



The hammer is distinguished by a yellow color, and full retraction of all the motion parts. The "wings" are in the closed position or positioned axially with the handle and the "rods" are fully retracted.

The cannon is distinguished by a cyan color and full extension of the motion parts. The wings are tilted outwards at an angle, and the rods are at full extension.

Immediately the engineering and design mindset went to work. The major question: "how can I replicate these shapes with enough rigidity using manufacturing methods available to me?". Immediately I began to gravitate towards plate methods for the majority of the body work, which meant waterjet and laser cutter. I had little experience foam and freeform sculpting, so I naturally gravitated towards 3D printing for high volume work of complex surface geometries. For materials, I scavenged. Luckily for me, the MIT Hobby Shop was undergoing renovations and were generously donating materials to reduce the amount of stock they had to pack. I started with a steel pole for the main mast and went ahead from there.

Design

Basing everything off the 1" steel tube presented some proportionality issues. The weapon appears to have a larger diameter mast than 1" when compared to Jayce's hands. Still in lieu of saving money I persisted. Below are some captures of the modeling done in SolidWorks.



 


I started with the 1" dia pole and began modeling the hammer's most distinguishing features. In my mind, this was the "lamp" shaped bulb on the bottom and the four "wings" on the sides.




Construction

I decided to build the hammer from the inside out. This way any imperfections that could propagate through the design could be accounted for in parts not yet made. However items that would be 3D printed could be done in parallel since they take far longer than traditional machining techniques.

First order of business was building the frame. I enlisted  the help of a friend to waterjet some aluminum at CSAIL.



After some sanding, things began to take shape!


For the first round of 3D printing, I opted to finish the body components first. These were made on a Stratasys Dimension 1200es with lowest fill density settings.

 

Upon assembly, I discovered them to be fairly good missile launchers. Maybe reuse for future work? :P


Suddenly, the body appears! Starting to look like a Debonair Jayce Mercury Hammer!

 




 

Now its time to add the motors. To make them hammer duty, I had to cut a corner off the gearbox but more importantly I had to replace the shaft. Having that lengthy 12" dual shaft was key for my dual use clutch idea to work. At the same time, I also pushed some ball bearings in the frame to help alleviate off axis loading on the motors.

 

 

 

Speaking of motor work, I bet it isnt quite obvious how so many mechanisms are being powered off a single motor. Well, since this design uses pure rotation to change the angle of the wings, the gearmotor makes sense. But what about the linear action of the "rods"?

 



For this I am implementing an elevator mechanism powered by a tension cord. Basically, there are multiple stages that can move linearly along each other all connected by a string. The string is wound throughout the stages. When the string is taught, the relative length decreases and forces the parts to move. This idea would be very difficult to implement in such a small space and with limited materials. However, it turns out to work in my bench tests! Hooray concepts!









 Next came the flurry of laser cutting. All the non-structural paneling was done in craft wood (thin plywood), laser cut to shape, sanded, and painted.

 




I would like to shout out to a piece of software called 123D Make. This program from Autodesk takes STL files and affords you several methods for creating its volume. This was incredibly useful for the "wings" because of their high volume but desire for low weight. I use 123D Make to make the "wings" from several slotted panels. Then I joined them together with a dab of super glue.




Now things are beginning to take shape!

 

 

 


The next hard part was figuring out how to skin the "wings". I had  tried several things like covering in duct tape and filling with expanding foam (very messy). I ended up exporting the faces of the "wings" as dxf files with sketched bend lines and laser cutting from "tank board", aka the backing on notepads.

 

 

 

From then on, it was about making duplicates of things that worked, decorating, and making finer details. Here are some laser cut decorations for the body face panels, the tips of the "rods" and some spray painting. I have the hammer here suspended using fiber straps from a garage assembly. One unfortunate aspect was the hammer ended up being really heavy or at least feeling very heavy due to physics. To help relieve weight, I tried to pocket the metal pieces. The heaviest part ended up being the "wings" but not much could be done about those now that they were assembled.

 

 
Despite all the hard work, I could not actually finish the fully functional hammer. Because of the ~16 hour drive to Atlanta for Dragon Con, I had to focus on decoration instead of mechanics. As a result, I could not properly debug issues regarding high stress points in the elevator mechanism, or clutch tuning for the wings. I decided to lock Jayce's weapon into a hammer configuration for the duration of the trip. Here are the final pictures.

 

 

Even though I didnt do much with electronics this time around, its worth noting. I left out the LEDs and effects and wanted to focus on purely mechanical aspects. In that respect, I only needed a method of transmitting power and the ability to reverse the direction of current. I was able to do this easily with a DPDT (dual position, dual throw) switch and a push button. The push button was used to flow current (read: complete circuit) and the switch was used to swap the direction of current. I could use two single throw switches, but this method is more fool proof since there is no shorting condition.


There was some cloth involved, but it did not involve much work on my end. I essentially bought towards a white tuxedo with tailcoat. Ebay is your friend in this case.



Implementation

I bought this guy to Dragon Con 2013 and later to Anime Boston 2014. At both events, the hammer was well received. A lot of good comments about detail, craftsmanship, and OMGWTFSOHEAVY. The question I loved and hated to hear was "Can it actually transform?!". Because it was essentially broken and perma-hammer mode it was heartbreaking. I had to simply respond, "I accidentally did the thing."

Dragon Con 2013

 

 

 

 

 

Anime Boston 2014

 

 

 


I hope you enjoyed this very late recap of this build. I was rather sparse on some sections because of the last-minute rush; I was not able to document those stages very well (with regards to painting and wiring). Still I would like to say a few things.

First, a thanks to my friends who supported and helped me through the build. This includes Charles Guan, Steven Jorgensen, Julia Hopkins, and many more!

Second, I would like the point out the title of this post "... Version 1". There was a version 2 supposed to debut at Anime Boston but could not be finished in time. It will be done by the next convention however. See you guys are Pax East 2014!

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Some photos taken by Ace T. Cosplay & Photography
Some photo taken by Zuli's Cosplay
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Debonair Jayce Cosplay v2: Transformation Complete

April 18, 2014, 12:55 am
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Last post I detailed the build for my Debonair Jayce Mercury Hammer prop. It was intended to do awesome things like transform and light up but failed because of my cheapness in design. Since Anime Boston, I've beasted through a tough 3 weeks (and $$$) to bring version 2 of the Mercury Weapon to Pax East 2014!

What Didn't Work: In a Nutshell

  • Dual purpose motors: I was being stingy with my spending and tried to make a component ill suited for the application work in my design. The double purpose motors were an interesting idea that should have saved weight and space but there are better alternatives.
  • Heavy metal \m/ (and other materials): I used materials that were free for me (1/4" 6061 aircraft grade aluminum for example) but absolutely overkill for a prop. They were durable sure, but EXTREMELY heavy compared to the pinkfoam standard of most props.
  • Color Scheme: The ivory was just a bad idea. Without a good primer behind it (plus recoating over old colors) essentially made it look like an old Macintosh computer. The static colors of yellow-gold placed adjacent were a nice barf color, esp when juxtaposed with the ivory. 

What Will Change: Minor Modifications

  1. Functional Mechanics: This means subdividing the mechanics to more "comfortable" technology, even if it costs me a bit more. This meaning I'll default to RC servos for the wings and try to make a screw-based mechanism for the rods.
  2. Actually Integrate Electronics: The previous version did not require an microcontroller because it was all DC driven at main voltage with clutches to compensate for physical stops. This version uses servos which input a waveform with particular properties. I would need a microcontroller or at least a 555 timer circuit for this. Although I am aware I could achieve this using passive components and a 555, I enjoy the visual interface of the MCU IDE and ease of change. The latter will be particularly useful for debugging values later (LED color, servo position, etc).
  3. Change of Materials: If it can be helped, all metal parts will be changed to high impact and tensile strength plastics. This should provide high strength at less weight and more color options! I would also like to try using this very popular pinkfoam that friends like Pizoobie use.
  4. Change of Dimensions: A second look at the hammer revealed to me that some of the proportions were off. I will attempt to remedy those effects when I update my components and functions
  5. Change in Color Palette: Although I still understand the weapon is majority silver/chrome, I still feel that the majority light with chrome detailing better suits the cloth aspect. Think of the weapon as a reflection of the user. With that said, I am only planning on simplifying the colors. Flat white (glossy or matte IDK) with chrome detailing. If you follow the skin in-game, the silver parts will be white, and the gold parts will be chrome. I will use LEDs this time for the areas that actually change between forms.

The Rebuild


Few hours with the SolidWorks models and the hammer was born.


The first thing I really did was think of ways to reduce the size of 3D printed parts. In a sense it is cheating with sculpting but the properties of honeycomb ABS are perfect for my goals. Still, I wanted to handle some of the load on my printers instead of just the IDC Dimension 1200es so I split the parts into sections that minimized supporting material.


The cut model shows a lot of the new magic inside the device. Instead of having a huge metal ovular plate, I split that section into halves. A skeleton frame of delrin plastic supports these floating panels and gives the appearance of a full volume. 

The purple rectangles are Turnigy brand RC servos. These will drive a 4-bar mechanism  that translates and rotates the wings outward. The pictures below elaborate on the new motion. The T-shaped bar is the piece where the wings will mount. The T shape in particular is to distribute the mounting points so it is more stable.



This is far more accurate than the single point rotation of the previous design. Furthermore, the 4 bar contains singularities which help reduce the constant loading on the servos. This will aid in their ability to hold position, a huge problem that plagued the first version.

What are those four cylindrical things? Glad you asked! I originally wanted to attempt a nested lead screw concept to extend the rods but I soon realized it was not feasible when I tried to design it. The second alternative are pneumatic cylinders. These provide quick response articulation of high volume linear motion in a compact initial configuration. Since nobody sells 2-stage air cylinders, I had to design them myself.



Air will enter through the bottom and fill the chambers composed of 3D printed endcaps and polycarbonate tubing. When pressure is released, an internal spring will retract the pistons. This is how I expected them to operate anyway. 

If you have pneumatics, you need to have air storage. Luckily, since I decided to move the batteries up to the hammer end, the bulb was now vacant. I stored a series air tank in the bulb and length of handle and left ports top and bottom to be filled and allow passage of compressed air.


Then the construction started. By this point in time, it was the week before Anime Boston. Could I finish it? There was only one way to find out! While I had the 3D printers running, I had the white polycarb and delrin waterjet cut at the MIT Hobby Shop.

Fresh prints of MIT. Three of these actually failed because I ran out of material qq.

Stratasys ABS P430 works in the Up Mini's! Slightly different color but much better mechanical properties.

The adjoining pod paneling were held together securely using a T-nut strip idea. No locating holes! just bore, tap, and arbor press!


Began assembling the oval structure in the center. Note how the ovals are cut in half. This eases assembly, servicing, and makes material conservation more effective. Also, that chrome!


Spray painted over the 3D printed ABS. Despite sanding, the striations are still very visible. At this point, I hadn't learned how important primers were yet. I opted for another coat to attempt a reflective chrome finish.


The bulb also suffered from that effect. Hilariously enough, I applied primer after the silver coat to get a clean flat white. I should have primed the entire structure, then detailed with the chrome. This probably would have helped with the paint bleed I experienced as the dripping paint follows the 3D printed layers like channels.


The chrome looks like wrought metal doesnt it? Actually kind of cool if I was trying to get that effect.
Now we get mechanical! Here is the compound air tank that will be storing my pressured air system. Its not a lot of volume, but I should be able to get one or two pops off for a good show.


This tank seats into the bulb like so. The mast goes over the longer storage tank.


Now we turn to to the wings. Cutting huge sections of double layer pink foam on the hot wire cutter...



... I can then hot glue to the table of the shop bot. What is a shop bot? An enormous CNC router! See the video below.




We end up with this.



And then this!


Because I was using a 1/2" ball endmill, there are some pretty heavy mill marks on the surface. Luckily, pinkfoam takes very well to sanding. I used an 80 grit sanding sponge to clean up the surfaces.

Experimental coating idea! My buddy Charles Guan made too much microballoon epoxy, so we slathered some generously over a spare block of foam. The result was a perfectly smooth hardcoat! Takes well to painting too! Below is a single coat of chrome.



It was so good, I applied it to my final pieces as well.


While that dried, I turned my attention to the electronics. I build a simple test circuit using a solderless breadboard, an arduino nano, one section of RBG LEDs, a limit switch, etc.


Since I was expecting using ~12v for the LEDs, I knew I would have to stepdown the voltage for the servos. A Turnigy voltage regulator drops the voltage to 6V instead of 12V. Test video below!



Once it proved to work, I moved it onto a solderboard. To be honest, leaving it on a solderless breadboard would have been more convenient. However, I see some potential in making cosplay electronics boards. hmmmm.


The board accepts seven inputs of RGB LED strips, and four servo inputs. To trigger transformation, it reads a digital input (like a switch).


Next soldering LEDs! If you were ever curious, you could actually achieve a variety of colors just by changing the voltage; you dont need to buy the LED strips with the controller. See this PDF for the details! Luckily, since I only needed yellow and cyan, I just needed to change which pins received full voltage.



Time to separate it from its power supply umbilical cord! The batteries were made from old and unwanted A123 cells. I wanted high capacity mainly (2300mah) but the added benefit of free and "beast mode charging capable". By the latter, I mean the lithium iron phosphate technology can be charged safety at 15 times its capacity, further meaning I can recover from low voltage at conventions quicker.


Wires and tubing are transmitted through the hollow polycarbonate tubing with a few holes.



With a bunch of sections done, it was time to simply put them all together. I was able to obtain some pneumatics components from old FIRST robots but had to buy a smaller gauge and cow-shaped manifold for the outlets. I was originally considering a network of tee fittings but it would have been too space consuming.


This will be mounted inside the side compartments with some screws.


Electronics mounted. The batteries were shrink wrapped to add protection. They are velcro mounted to the sides.


Remember those four bar linkages? Here they are fresh off the waterjet! Cut from 1/4" 6061 aluminum. The purple pieces are aluminum servo horns from Turnigy.


Installed on the sides.



Here is an important less about servos: not all servos are made alike! I had them wired previously to share two digital pins. Technically this should have worked since the servos are opposite each other with respect to the diagonal plane. However, we find they are not alike and need to be individually addressed in order to fine tune position. I ended up taking two of the signal wires from the servos and soldering directly to two digital pins on the arduino. A bit dirty, but should work.


Updating code...



To attach the foam pieces, I was going to hot glue weldnuts on the backside. This way I have something secure to bolt into and allows for the pieces to be removable. To make the holes I simply aligned the back pieces to the foam and poke holes into the foam. Then I bore it out by hand to a final diameter and lightly counterbore with a 3/4" endmill.


All four!


Wither those attached, I could do a semi-real simulation! Here is the hammer...


... and the cannon!


And video!


Now for the last two days, it is time to rush build the pneumatic pistons. How much have I gotten done so far? Well uh...


2 hammer Jayce <3 br="" nbsp="">3>





Debut!

I didnt get to go until Saturday and even then I woke up late! I rushed hurriedly to the Boston Convention Center in hopes of making the cosplay show in time. I didnt even enter the doors before I was quickly noticed. After the first transform the reaction was insane!

I met some cool guys...



And ended Saturday with this nice featurette on the League of Legends tumblr. 

http://leagueoflegends.tumblr.com/post/82497432270/the-jayce-cosplay-is-ridiculous

Just a four second video that was reposted on reddit.

http://www.reddit.com/r/leagueoflegends/comments/22vp4s/amazing_debonair_jayce_cosplay_at_pax/

And I became semi-famous instantly. At least for a day anyway. :P


 





Reflections and Conclusions

This weekend has taught me that whatever I cosplay, I MUST make it mechanically articulated and electronically fancy! First, I kinda enjoy the attention (even if it does take me 30 mins to go down the hall) but more importantly there is some great educational opportunity here. I would say  70% of the people who took my picture wanted to know how it worked and while that is an incredibly broad question I was able to stimulate good discussion about some engineering topics.

I believe cosplay can be the intersection between art and engineering. If I can build something to capture an audience, I can hopefully inspire them to investigate and learn more. This goes for anyone, no matter how young or old.

Otherwise, I really need to start these projects sooner. 1 month is an impressive number to put up but boy am I exhausted qq. I'll be spending now till Dragon Con fixing the pneumatic pistons, which should be a manageable task if I just keep up this pace.

Useful Links

Arduino microcontrollers
Hobbyking: great source for batteries, RC equipment, and Arduinos
Big Blue Saw
McMaster-Carr

Special Thanks


  • Thanks to everyone who was a part of the making or picture taking of this version of the hammer!
  • Charles Guan for hosting a build space, helping with printing, mixing too much epoxy, and helping with machining!
  • James Penn for taking the semi finished pictures and video!
  • Everyone for letting me know that I got fed on reddit!
  • Riot Games for making an awesome champion and posting that mini video!
  • Cathy Heo for your moral support and pro sanding ability!
  • Brian "Iron Man" Chan for use of the Hobby Shop Waterjet!
  • Amy "Pizoobie" Zhao for her consultation on foam coatings!
  • Cynthia Lu for finding the RGB LED guide!
  • Thanks to my PI Anastasios John Hart for letting me slack off a bit that week XD
  • Happy Birthday to myself!
  • And last but not least, thanks to the League of Legends Cosplayers Facebook group for being a constructive and awesome community! I think we can all agree the positive atmosphere in that group keeps us coming back to make another costume!
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Bug Love Robot: MegatRON for Dragon Con

September 5, 2014, 12:12 am
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I sense a change in the winds! Seriously, its getting cooler. That means Summer is ending but more importantly signaling the arrival of Dragon Con, my annual pilgrimage to Atlanta, GA to visit friends and fight robots at the Robot Battles and MicroBattles Contests. Last year I brought DDT and Dead Meat (formerly Turboencabulator) but with Dead Meat, well, dead I needed another entrant to take over the main event. Luckily I had built a mega version of my original beetleweight, Ron, and could think of many ways to make him worthy of the stage.
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After Motorama
MegatRON was pretty sad offensively  after Moto. In its fight vs Shaka, the dustpan was wrecked. Although Adam helped reweld the pan for the rumble, the pan was once again split open by Hyperactive and . To make matter's worse the saw arm motor smoked when I was using it as a hammer. It had a pretty sad ride back home next to the nearly victorious Uberclocker. Maybe some of that luck will rub off on it next time?



Uh... a bit more than rub off.
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The Love Robot
To satisfy the rules of Robot Battles, the robot had a tip speed limit for all spinning weapons. This meant that the saw cutter could no longer be used with its current configuration. Instead I opted for a lifter and clamper mechanism similar to that of Uberclocker but utilizing the same hardpoints on MegatRON and general dustpan shape. After a first-pass concept, I flushed out the below design:



Looks too much like Uberclocker to me although the components are different. This design uses dual Banebots P60 132:1 gearmotors with RS550 motors. At ~10 inches from the pivot point, this configuration should have tons of lifting torque at the tip and more than enough speed to boot.

Additionally, I was feeling extremely lazy at the time. Not only was I taking courses and doing research but I had an industry short course of my own to teach and a conference the following weeks that needed a poster that I had not made yet. In short, I was strapped for time. If I didnt have the gearmotors on hand for the project, It couldnt be done.



This design turned out to be more feasible. Say, what is that beastly box object tied to the main lift pan?

It is a Tonegawa PS-050 super ultra mega cray servo! I found this sifting through old FIRST and decided to give it new life. This guy would make the top clamp arm at over 1200 oz-in of torque!

However, the servo has plastic gears which are still concern for stripping, especially in this high torque application where backdriving is a possibility. Similar to the lifting pan, I will integrate a slip clutch to relieve the servo under torque but also use spring steel strips as the gripper mechanism. My hope is that the flexibility of the steel is enough compliance to prevent damage to the servo.

The real challenge was converting the servo horn into a more useful medium. I had two options. The first involved milling a relief into the face of a shaft to match the servo horn geometry such that the horn could essentially sit in the relief and transfer torque by twisting against its features. The second option involved modifying the horn to essentially emulate these servo spine shafts from Servo City. I decided towards the latter for ease of support. Below, I describe the steps I used to create the part.

First I turned the horn into a round. No particular diameter, but the more nylon meat the better.



Next I counterbored both ends of the ceramic-coated aluminum shafting. One end should press fit the nylon servo spline but the other end diameter mattered less since that feature is only meant to pass the head of the servo horn screw. In this case, I needed a through diameter for the head of an M4 screw.




I pressed them together and drilled a #2 radial set screw for good measure. I could now assemble the servo shaft assembly.


After machining a few thousand standoffs, the weapon comes together with some long tie rods.


The top clamp servo is also mounted with standoffs. Now I can add the clamp clutch and clamp arm!



Pretend-o-bot! Looking good so far!

Very little would change with regards to electronics. I removed one of the 85A bot bitz escs since a single esc could power both lifter motors. To connect them together I utilized what I call the "shotgun connector".



I mean a double barrel bullet connector could be a shotgun right? Id love to see someone scale this into a six-shooter or something...

The servo is beastly enough that it would need far greater current than the 500mA or so from the ESC BEC. However, with a 12V max limit, I would need a method of stepping down the main battery voltage. Luckily, Charles had experiemented with DC-DC converters for herpy nano bike. He simply used a BEC and changed the feedback resistor. This tricks the converter into supplying higher voltage but at the expense of current.

After those changes it was time for a test! Seems to pass.




The robot wheelies very hard on accelerating which makes scooping robots or object very difficult. However should it happen the pan turns out to be incredibly quick! It is a standalone flipper!



Later that evening, Charles finished up his modifications to Uberclocker so we decided to spar.



From the video, you can easily see how detrimental the wheelies are. Most times, I jump right into his grabber. However, should I keep mobile the robot is still very maneuverable and has lots of flipping potential.

Aside from the expected scuffs, the robot took no damage and performed as expected. From this point on, I decided to tidy up the wiring and take the finish shots.





And this concludes the build report for.... what am I naming this thing again!?

Charles and I agreed the robot looked like a bug, with the red grippers being eyes or the spring steel strips being antennae. This immediately turned towards one of our favorite inside jokes, "bug love tree". This phrase was uttered by a professor during a robotics competition using broken English and has been cherished by us ever since only to rival that of "control systems potato". Change tree into robot and ship it. "Bug Love Robot", perfect.

How much love with Bug Love Robot give at Dragon Con? Read the event report to find out!
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New Facebook Page!

October 2, 2014, 3:26 am
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Hey! I haven't been as absent as it seems; I've just been exploring other social media opportunities!

I created a Facebook page for The Variable Constant since it is easier to interface with people. Expect smaller and more frequent updates there, and big wholistic builds/analyses here!

Please like my page! =D


Cheers! I will leave you with pictures of the trophies I machined for the MIT Mini Maker Faire Robotic Combar Tournament this Saturday, October 4th!


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Attrition: The Unspoken Hobbyweight

January 17, 2015, 7:09 pm
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Before I get into this long long post, I want to mention the existence of my Facebook page. There, I make smaller posts on more incremental work (which is where I've been more recently).


So if you want to see more consistent updates, I suggest you go there and follow :P
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Prelude:
Long long ago, I built a hobbyweight with the help of fellow bot people like Brian Schwartz and Casey Kuhns. This was back in 2008 which for me was high school and my resources were limited so I would like to take yet another moment to thank those mentioned above. However, I did not blog about it because my blog did not yet exist. Later versions of the robot were also gone unmentioned (such as my Motorama '13 and Motorama '14 posts). I find it now necessary to log the development of this power-dense combat robot.

2008-2009:
This robot was a drum spinner (as was the flavor of the month) and was a wonderful blend of scavenged robot parts. It used a set of 5:1 'mabuchi' gearmotors I scored from ebay, a set of BB 12-45 escs I bought off a leaving bot member, and batteries given for doing a favor for another bot member. I bought a 40 mm copier stator to wind the brushless motor and had machining help as mentioned above. Furthermore, I had machining services donated by local companies to make my drum, an odd combination of 4130 for the drum body and A2 tool steel.



Please for heavens sake do not weld those steels together. EVER. Looked okay but was difficult to heat treat you might imagine...



Either way, this was my first big bot I made and it debut at Motorama 2008 where it went 3 wins and 2 losses to Igoo and Surgical Strike.




It had many notable flaws:

  • Banebots escs overtemp shutoff from the high current draw mabuchi gearmotors
  • poor detail mechanical design and material choices allowed for bent frame and lockup
  • weight distribution made for poor inverted driving (and poor ability to self-right)
  • additional precautions to secure connectors also required

 It was also the first robot I built featuring a custom made brushless-in-weapon system. I'll attribute the original idea to Corona and Skittlebaru but none have gone as far to put the esc inside. Will bales "Fluffy" came out later utilizing my old 5" drum idea having everything except the drive motors inside the drum. Lets just say there was a reason I didnt finish that version of Attrition. The things learned from this robot would carry in designs to come. Additional pictures from long long ago can be found here:


2012-2013:
By now I was in college at Georgia Tech. My activities at local events and Dragon Con had interested enough friends to justify the "Georgia Tech Fleet" to drive from Atlanta to Harrisburg for Motorama 2013. I dug Attrition out from storage and decided now was time to address its shortcomings.




I started from scratch. Time to apply new knowledge on mechanical design, materials, and even 3D modeling (since by then I had my SolidWorks professional certification). We would decrease the footprint to save weight and increase the durability of outer armor. For the same goal, we would also downgrade the weapon assembly. The gearmotors would have to go; Instead I picked up four higher reduction planetary units with 'long can 400' motors attached. This new version went by many names such as Tofu or War Machine but decided to keep it as Attrition to indicate its lineage.

Let's do some planetary gearbox math:
A single stage of a planetary gearbox can be calculated by:
(Ring + Center)/Center:1

Pinion :11 T
Sun: 17 T
Ring: 46 T

Stage 1: (46+17)/17:1
Stage 2: (46+11)/11:1

Overall: 19.24:1
This number was good according to my calculations should yield ~10 mph with my long can 400 motors.



To make everything compact, the keyword was 'integration'. I built the gearboxes into the frame rails to save space. The electronics were repackaged into a small cube to reduce wire space needed. I was able to find  the perfect battery to sneak into the remaining space.





Drive test showed the robot was fairly nimble. I dont remember if I had switched to Banebots RS395 motors yet or not. Either way this video showed that I could not use round belts like I usually favor. On high acceleration moves like direction changes, the belts would slip. This made driving with the drum impossible as I later discovered. Later i switched to waterjet machined XL timing pulleys.




The drum was simple; I cut the original drum from Attrition reducing its length from 8" to 5.625". The motor was a bit more challenging. To simplify the design I kept the esc out of the drum. This was a decision made based on 'Cake's matches where the drum would break free and eat its signal or power wires. I also decided to not route wires inside the shaft. This was so I could preload the inner race bearing assemblies in the shaft for higher rigidity and high frequency performance. As such, the wires would exit with a new concept I had involving a large ring bearing on the motor side.









The original concept was to build the internals from several stacks of waterjet material. However the drum was a bit warped so any precision machined parts would not readily fit inside. I ended up wrecking a motor in an initial test and remachined the entire assembly from a single round of aluminum. Some fully assembled pictures.



Now, time for the money shots! The LED vag was a nice touch too...




This version debut at Motorama 2013 where it faced a number of tough opponents including Zandor and the undefeated multi-time champion Cataclysm who won 2nd and 1st respectively. Attrition went 3 wins and 2 losses for 3rd place, going undefeated for 3 matches until he met Cataclysm on Sunday.





Somehow, Attrition came out in good shape. Aside from blemishes on the top and bottom plates, the majority components including the drum were fully operational. The source of my demise was actually lack of spares. After my match with Zandor in the quarter-finals, I was down one drive motor and went into the Semi-finals against cataclysm with only one drive side. This put me at a huge disadvantage and lost decisively. Shortly after, I lost the losers bracket finals to Zandor because of my lack of drive side. Originally the culprit was a broken magnet. The replacement given by another builder ended up failing also because of pinion slip.




2013-2014
Losses at Motorama 2013 were disappointing to say the least. This year's emphasis would be into the drivetrain. I wanted faster and more reliable. Now at MIT, I lost a valuable resource at the Georgia Tech Invention Studio. However my research afforded me new capabilities I would try and leverage when possible. In addition to remaking many outer armor plates, I also swapped the Banebots RS395 motors for the original long can 400 motors and remade the center timing pulleys from 3D printed material. I believed that high starting torque was the culprit for pinion slipping.




Another decal with lewd LED placement was needed.



As fate would have it, I was wrong. At Motorama 2014, Attrition went 3 wins and 1 loss in a round robin format for 2nd place. Agility was useful in my first match against the pneumatic flipper Jumbonator but I lost a drive side again after a win on Upchuck. This was a fatal blow against the strong drive of Isotelus Rex as I could not maneuver for a good hit. The FDM material actually split and rendered the center pulley useless. This was from the high stress concentrations near the 6mm drive shaft to the ~25mm center pulley. This could easily be fixed with a larger diameter intermediate made of metal.




However, another defect surfaced that I had not predicted. The A2 teeth, after years of battle, finally broke during the match against Isotelus. I suspect this was due to fatigue as nothing on Isotelus could have done that. However I note that points were given to him for 'damage' to my robot as the judges pointed out when Attrition had finally spun down after the match. Closer inspection of the welds show little to no penetration into the wall; it was no wonder they had broken.

Present Day:
No place in 2008. 3rd place in 2013. 2nd place in 2014. This year we pull out all the stops. At Motorama 2015 we will go for the prize!

I here conclude this post as a documentation of my first 12-pound combat robot. In another post, I will summarize the efforts to prepare Attrition for Motorama this year which includes professionally made drums and extensive drive modifications.

Video of all Attrition's matches can be found as a playlist on my Youtube. I have placed the direct link below.

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Attrition: Final Push for Motorama 2015

February 6, 2015, 1:56 am
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Last post you saw a glimpse of the tragic history of my first and only Hobbyweight (12) combat robot. At the end, I declared I would try my hardest to take the title this year and have implemented extensive upgrades to make it happen. It goes without saying that I did a complete teardown of the robot and its systems but here are the main points to remember moving forward.

Super-awesome new drums from Westar Bot Shop (Team Whyachi)

Last year the drum from 2008 finally gave up. Usually this is the point where builders will reevaluate their design and decide to build an entirely new bot all together. However seeing as how the chassis was nearly undamaged, there wasnt a point in rebuilding that so we will just build the drum again but better.



For this, I had the drums sent to a professional machine shop. Team Whyachi has been providing fabrication services for years and resulted in years of super happy customers. You can find their page hyperlinked numerous times above. I sent them some relatively simple drawings  and Clint Ewert immediately went to work. I started conversing with him maybe Dec 31 2014 and I had the drums back to me 1-2 week of January. Talk about quick turnaround!



The drum is still the same dimensions as the previous one (3" OD, 2.75" ID, 3.625" T-to-T) but the materials are now compatible. 4130 steel all around, hardened afterwards. I asked for 50-55 C Rockwell but some metals treatment literature say 4130 can only be hardened up to 45 C. I'll take the spare to the Rockwell tester to see how it actually came out.

BTW, I bought 2! Two drums for a total of $650 including shipping. Whyachi paid for materials, did machining and services, and a batch of heat treating which makes this a phenomenal deal! Plus, all dimensions are within 0.005" tolerance specification which is ABSURDLY GOOD for welding and HT. Would recommend again!

The bigger issue now is the fact that there was some internal damage to the motor components. While the Whyachi drums were on the way, I cracked open the drum to harvest the relevant components.



Oops. Isnt that supposed to be attached? This was the worst problem among the shattered bearings and dented races because that motor isnt cheap by far. I evaluated at this point if I should purchase a Turnigy equivalent to replace it.

What I ended up doing was JB welding the motor to the shaft. While this make it an incredibly permanent solution, I recognize that the state is fully encapsulated by the can and drum; It should be simple enough to salvage if things go completely bad. I think I am fortunate that none of my motor wires sheared. This gluing process was done with the guts in the frame. Because the center races are all in compression, it locates all the components securely.



I decided not to paint this drum. Partially because I was impatient but also because spraypaint would have fouled my tolerances inside the drum. I may consider painting the spare if the first drum gets damaged.

Revamped drive system

The majority of work was actually put into redoing the drive train. As mentioned previously, I lost a good majority of matches due to drive faults. The first modification to take place was the center double pulley. Last year the FDM pulley had far too much torque at the shaft and displaced the set screws threaded into the pulley.



This year, I borrowed some design concepts from Charles Guan. I started with some 5/8" aluminum hex and turned those into intermediate shafts. The hex would go over the nominal gearmotor shaft providing me a meaty aluminum interface for set screws and the like as well as a hex cross section for torque transfer. Snap rings on either end would prevent the pulley from sliding off the ends.



The pulleys themselves were selective laser sintered (SLS) nylon from Shapeways. They were my usual 20T XL pulleys but designed to go over the hex. I got them in black and red; the red set being the test set. I wasnt too certain about the durability of SLS parts so I got the red set to test part durability. If at any time during a test I saw red  powders on the bot I would determine they pulleys not combat grade. Black would have been much harder to spot.



The entire setup comes together like this:



Pretty neat eh? Initial test drives with the old motors were promising. No red flakes to be seen, nor belt slipping or tooth shearing. We'll run it later in the week with the weapon for some harder durability tests.



Next was the motor. Currently, I use "long can 400" motors or "480 sized" motors. I used to use Banebots 395 motors but they were too slow. See the difference between last year and the year prior. That shows nearly 4 mph of difference in speed! There are a number of 480 sized motors on the market but they are usually used for direct drive prop airplanes which means they are typically low voltage, hot wound, and timed. The trick for me would be to find something mid voltage, mild wind, and neutral timed. This search proved to be near impossible.



I ended up getting four of these 480 motors from RC parkflyers. But testing proved that they were actually 6V native motors and I quickly burned one out. Ugh.

A second option was to modify the mechanics of the gear reduction. The gearboxes are largely custom inside Attrition so this would not be easy. Essentially I needed a way to replace the existing stages with low reduction stages only. Some searching on Alibaba for 32mm planetary gearmotors turned up some interesting concepts. I found my 19:1 gearmotor model but the vendor actually sold a 14:1 and even a 11:1! What did this mean? This meant other stage combinations existed and this modification was in fact possible.



I did my research on gearmotors. Servo City sells 32mm gearmotors as well but their spec sheets are incomplete. Super Droid Robot Land provided the manufacturer's specification sheet which clearly indicated either 11T ot 17T sun gears. BINGO! That means there are only two types of reductions and they are either 3.7:1 or 5.2:1 as previously mentioned.










Then I combed through their standard reductions and factored their values by the two stage types. From this I can accurately tell what stages and how many will be inside each gearbox. I bought a 51:1, which is composed of three 3.7:1 stages.










Looks like the first stage is plastic. Not a problem since the other two were metal. Now I could use the slower but mild wind Banebots 395 motors to give me about 8.3 mph. It isnt as fast as last year but should accelerate faster. Plus, I can actually buy spares! While I was at it, I decided to replace the worn components in the gear motors. New shafts, new bearings, new steel shims!

Actual thought put into front attachments

Now this isnt a primary point of failure, but while I was putting my all into retrofitting the robot I might as well address this as well. Typically, I would run with or without wedgelets which were little slivers of titanium held on with stacks of UHMW shims that acted as spring loaded hinges. It was a neat idea for awhile but the ultimate lack of durability in the UHMW was a failure point in that they were easily sheared off.

After fighting designs like Thomas Kenny's "Shame Spiral" and Pete Smith's "Isotelus Rex", I realized there is a clear winning design to fight the "Solaris" drum bot design and that magical snout was the trick. To counter battle, I would play the arms race against their ramming plows.



I had these modeled in previous models but never took the time to make them. Now that I had "MegatRON" parts being made from Big Blue Saw, I decided to throw on some small parts for Attrition. Now I have a number of wedgelets in various lengths to handle general purpose wedges and specialty designs.

The one type of spinner Attrition has somehow managed to avoid are massive horizontal bars. For these designs, I have some additional defenses in the works, but no need to reveal them yet ;)

Loads and loads of spare parts

This time, I will not lose from lack of preparedness! I am bringing all this and more in case I have failures. These are the expected points of failure so it is possible other things can happen. However, should any of those parts take damage, the bot probably deserves to be retired. Lets hope I predicted correctly!



At this point, we are more/less ready to rock. I'll be running some durability tests with Charles between now and then so be sure to check out those vids when them come out. Cheers and bot on!


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Return the Victorious: Motorama 2015 Event Report

February 28, 2015, 9:04 pm
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Motorama may very well be the toughest combat robotics competition in the entire Northeast. With that said, it is very difficult to place in any weight class. By chance and skill, I was able to place in two weight classes of three entrants! G3 Robotics was able to end with a respectable 10 wins and 4 losses. See the bot specific breakdown.



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Silent Spring
No place (3W - 2L)

Finally here Saturday morning and still no name for the beetleweight DDT clone. Despite the controls oriented suggestions given by other builders, my friends agreed to Silent Spring, the name that Nate Franklin had originally proposed. Once I explain the reference people think its clever >_>

Regardless of the name SS's day started out rougher than most. During safety, the drive motors would not shut off! I traced the issue back to the receiver, which does not appear to support failsafe protocol on the elevator and aileron channels. Broke a few wires swapping back to the reliable OrangeRx 6ch receiver but that was quickly handled by butchering a bind plug. SAFETY ALERT! THE 3CH S.BUS RX DOES NOT PASS FAILSAFE!

Silent Spring v Rmr
Soon we were ready to fight and SS pulled Rmr, a fellow MIT bot from MITERS. This bot featured an overhead spinning bar and an O-ring track system for drive. 


The fight was against his favor since my blade could reach under his blade to land hits on his body without hit myself. However, without ANY driving practice on SS, It would be very easy to over travel after a hit where Rmr could get my sides or even a wheel.


Because of that, I played on the cautious side and took smaller pokes. One of the first few glancing blows actually did result in him landing a body shot, but without critical damage I was able to continue the attack. Still, some nice scars there.



Silent Spring v Time Warp
Now hearing I would be fighting the modified Trilobite kit, I decided to take my time in repairing the drive belts which appeared to be loose in my first match. I would need every ounce of maneuverability to escape this bot. On top of the Trilobite base, Time Warp featured an angular plow from what appeared to be welded and treated steel. There was no way I could bite through that plow but as it would have it, I didn't need to.


I spun up to full and decided to focus on keeping the blade forward. Time Warp came to me with the plow first and after several big hits the pins keeping the shaft on gave up and the plow came off. If it didnt break at the collar, it might have broken at the beak. Small cracks were beginning to form.



However the blade had slowed significantly by the end. I had not received any visible damage but I could not spin up the weapon. This time dependent shortcoming would plague me for the rest of the tournament.

Silent Spring v Devastating Moment
Joey and I had once fought antweights in 2008. His Swamp Woman vs my DDT. DDT managed to get the better of that one but only because SW was an unweaponed bot. Now Joey had a Weta kit with a custom steel eggbeater. It sounded mean!

Unlike In the Margins (Weta Killer), SS has a thick blade which is better for big hits and less effective for chopping or grabbing. I would only be able to get good hits on hard surfaces and so instead of aiming for the feet, I aimed directly for the weapon bar.


I was essentially relying on the robustness of the robot mechanics since at this point I had not sorted out the weapon ESC issue. If I stopped spinning it could be over for me. I got lucky this time when he shut off unexpectedly  after two big hits and couldn't continue.

Speed Wedge 3 v Silent Spring
I met Ian this year when I spoke to him a bit in the pits. It didn't take long for me to realize a quality builder and solid competitor. When I pulled this match up, I predicted a loss immediately. With the spotty ESC and his driving skill, attrition would work against me. Well, I don't need to say much more do I? Loss by judges decision :P



In the Margins v Silent Spring
AHHHHHHHHHHHHHH WHY DID I HAVE TO LOSE. The most horrible match up pits friends against friends in the loser's bracket and its not even the finals! Last time Aaron and I had fought was actually last year where we went 1-1 against each other in the total annihilation of Dominant Mode.


This year we both built bots to last. Plastic construction, horizontal disks. It was shaping up to be a good match... but ended up pretty sad. Two soft hits in, my power switch opened up and SS turned off. Slim got a nibble on my wheels afterwards. Ah well, Aaron will have to carry the flag for the both of us (but ended up losing to Speed Wedge 3 also :/)!



Beetleweight Rumble
Immediately after the In the Margins match, I put SS into the rumble. Literally, re-tightened the fingertech switch and threw it into the box. I used this time to play with the throttle a bit and see if I could discern the cause of the ESC problems. It looks like if I keep the weapon at max the entire time it will power up quite alright.


That was it for Silent Spring. A solid robot with great potential, hampered by some bad electronics. Without another competition in the near future, I'll have plenty of time to figure this issue out. For the time being, Silent Spring has succeeded in its primary goal: Be entertaining and don't get destroyed :)
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Attrition
1st Place (4W - 0L)

Having started so far in advanced, Attrition's check-in was straight forward. For the rest of the competition, all I ever had to do was swap out batteries and decide whether to use the wedgelets or not. All these upgrades paid off and made Attrition a clear winner this time around.

Attrition v Maul
Maul was another bot that came out of MITERS but one I had not seen before. Partially because I don't frequent MITERS much anymore but also because I was led to believe the robot was still being completed at the event as it was safety checked immediately before the match. - _ -

It appeared to be some sort of thwack bot with cutting tools for wheels. The chassis was made from a rather thick steel pipe and there wasnt any chance of going through it. So, I opted to punt it around until he tapped out.



Attrition v Hyper Drive
When Cataclysm totaled Apollyon in 2013, part of me cheered just because I wouldnt have to face this legendary wedge bot in the future. However, Mike sold the bot to master craftsman Jerome Miles who then put the drive setup from his 60 lber into it and renamed it Hyper Drive. Oh dear.

Hyper Drive is an appropriate name. It has two massive inrunner brushless motors coupled to dewalt gearboxes for drive. It could move and spin fast enough to do reasonable damage in a thwacking mode. If it were more controllable, he could totally dominate this match.

I decided to play it safe. Start with low drum RPMs and gain maneuverability. I also put on the short wedgelets to help with his front wedge. Shortly into the match, HD lost one side of his drive (gearbox slid out) and I was able to flip him over using the wedgelets. How inverted and nearly immobile, I turned up the drum to full to try and lay on the killing blow. That hit took off the wheel on his good gearbox and Jerome tapped out.



Attrition v Isotelus Rex
Here we are! I finally get to fight my pushybot rival! I knew ahead of time that he would be using the snout again, so I best optimize for driving. Therefore I employed the same strategy as I had against Jerome in the match previous.

Things were going according to plan. I was able to dodge out direct attacks from the snout and lay some pecks on the Ti guard. A few flips went in my favor to added aggression points. Occasionally the drum would contact the snout and I actually noticed white plastic flaking off into the arena. At this RPM (and perhaps because my teeth were still sharp) I could bite into this snout instead of being deflected by it. I started going head on into whatever angle I could and was still able to toss him about.

For the last 30 or so seconds, I turned up the drum again like I did against HD. At this point there was enough damage to the plow to render the snout ineffective. Some showers of sparks and a few more tosses for good measure to start strong, end strong, and give Attrition a shot at 1st this year.



Attrition v Isotelus Rex (FINALS)
Isotelus Rex and Ripto fought a close match in the loser's bracket finals. Amazingly, Isotelus Rex came out the winner after 5 mins or so of judges arguing. I figured I would run the same strategy as the first time I fought him but it turns out it was not needed. He suffered damage to his gearmotors in the match previous and was unable to make the repairs in time. This left Isotelus with one drive, which severely handicapped his awesome driving power. After a few hits, he tapped out and Attrition was crowned the 12lb champion!



Motorama couldnt have gone any better for Attrition. Progressing from 3rd, to 2nd, and finally 1st was a hard battle through the years but taught me many things about robust designs. I am happy to say everything I learned about engineering was well worth it and demonstrated in this little robot. Next year I hope to fight against my other rivals in the division such as Ripto and Cataclysm. This will be the true test of this robot. 
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MegatRON
2nd Place (3W - 2L)

With a tightened clutch and new dustpan, I had hopes for Ron at least as a pushybot. It has been forever since I had driven a non weaponed robot and in particular my old old design from my childhood. We would see what the future holds this year at Motorama

MegatRON v Candy Paint and Gold Teeth
The first match was ALSO against an MIT folk! I felt like they were trying to phase us out from the start! Even worse, it was against my buddy Charles and his mean overhead bar spinner. He told me he was going to spin slow and have fun. I obliged but encouraged him to make it entertaining as well. I put on the abrasive saw to make sparks but not penetrate his aluminum frame.

He did not disappoint. At the speed he chose to spin, a slight pertubation from Ron's dustpan caused him to flip over. However, he had enough torque to Tornado-mer dance! What followed was nearly 3 minutes of watching CPGT try to self-right with the occasional Ron interjection with the saw blade. Eventually, Charles burnt out his motor and CPGT was counted out.



There was some damage after the match! CPGT was wailing around Ron so hard, that one of the cast aluminum pillow blocks actually shattered and left the arm in danger of a single supported system. I was quickly able to hack a solution together by taking my spare P60 gearbox face and using it as the far end pillow block.




A very expensive pillow block - _ -.

MegatRON v Whammy Bar
Whammy bar looked to be a deadly horizontal bar spinner. What made it scarier, is the fact that nobody has seen it hit anything yet! Alex tapped out early in his fight with WB before they could make contact so I will be the first to feel its teeth.

I went out to box rush him but missed! Argh! He was able to get up to near full speed when we made contact. The Ron took the hits like a champ but WB could not. Somewhere inside his robot, a component popped loose and WB stopped moving. Ron, and his ineffective saw, moves on :P



Damage pics! That penetration!


Whammy bar adds a nice dent on the inner of one pontoon


MegatRON v The Magnificient Poncho
I've always been impressed by Poncho. It is such a simple robot but with power and good driving it can conquer the toughest opponents. Earlier in the competition, Poncho defeated last year's champ Triggo. I will have to break out my best driving to stop him.

I used a lot of spin tactics to deflect his charges since I knew a head on collision would most likely be against my favor. I had a wide wedge and sloped sides that could be used to scoop around his pushing angle. This was effective for getting under him.

In the second half of the match, I was noticing a lot of over steering in my driving. I could see from my driver's stand that my one side of wheels were free spinning! Ah! the banebots keyway had stipped out! Luckily I could still drive a bit but I was definitely trying to just outlast poncho at the end. We got stuck together twice which helped in stalling for time. (normally I would able to spin him out of the tray if I had both drive sides...) The judges voted in my favor and MegatRON goes to the finals!



Some pictures of the wheel casualties.

4 old megatRON wheels. Since last year.

Banebots keyed wheel sheared section.


Thankfully, Jerome was nice to give me two replacement wheels. they didnt match the 40A's that I had as spares, but they would work for now. Thanks Jerome!

MegatRON v Triggo (FINALS 1)
Oh man, it is finally time. Many people would fear fighting Triggo but to be honest I wanted this fight to happen. As soon as Triggo was announced over Whammo, Charles and I had actually cheered.

I knew this fight would be among the hardest I've had in awhile. And to not drive a weaponed bot make it all the more exciting. There is some thrill in depending on skill. Being the robot that could be destroyed, trying to outlast the stronger robot. That is what I was looking forward to and that is what I got.

Starting out a bit tentative, I let him spin up a bit because I thought the dustpan was steep enough to deflect him. While that worked for a bit, he caught the right corner of the dustpan and spun the bot around catching another edge and flipping Ron. I had the clutch relatively loose to prevent stalling the motor but in this case it proved harmful as Ron could not invert. I had to tap out  to save the robot before Triggo's next attack.



MegatRON v Triggo (FINALS 2)
This time, I went as hard as I could. A solid box rush from the start slowed him but not enough to stop him. From there I had to stay on him as much as possible and keep him off his toes. A careful balance of poking with the wedge would tilt him and force him to spin down or lose control.

However, the two hits from the previous match took its toll on the dustpan; it was slightly tweaked on the right side and could actually go over the shell as he teetered out of control. During these times I was unable to control Triggo and wasted a lot of critical moments.

Finally I was able to herd him into a corner but... Ron stopped moving! ARGH!  He crapped out in front of my drivers corner so I could see that the powerlink (an XT60) was much much higher than it was supposed to be. Meanwhile Triggo was slamming himself into the pan and into the walls to push himself free. When he finally escaped, I tapped out to prevent a juicy juicy free hit on the arm.



People tell me I was winning that match but I didnt really care. it FELT EPIC! And that feeling alone was satisfaction enough. MegatRON would take 2md place to the 2014 champ Triggo. No shame in losing in the finals to a spectacular robot.

Triggo, the 2014 and 2015 Motorama 30lber champion


MegatRON after the 2nd triggo fight

Triggo nibbled at the wheels.

.. and did damage to the dustpan

The right side corner which was already raised was further chewed by Triggo. The left side is still pristine!

To conclude this post, I'd like to shout out to the many many people who made this event a great success, a great time, and overall made the experience of robot combat a wonderful idea. First is my bud Charles Guan, who I give credit to for the numerous resources and help used in building my bots. He also drove the group of us through the snow to get to Moto. None of this would be possible without you man! Then I'd like to mention the MIT and GT crew for a friendly competitive atmosphere and help in repair time. I find that things are most fun when you have your friends and robot fighting is no exception. Not to mention their unyielding support. Xo, Aaron, Gabe, Chad, Adam, Dane, Charles, Paige, Cynthia, Rebecca, Ciaran, Ian, and James here is to you! And I really really hope I didnt miss anyone. I would also like to note exceptional builders who made it a really great time. Zac, Mike, Alex, Kyle, and Jerome were kind enough to offer me parts and help in times of repair. And most important are the folks at NERC who kept the show running. That's Ed, Beth, Jon, James, Kyle, Rob, and Mike and many many more Im sure. Thanks for making Moto one heck of an event!.

Attrition, 12lber champion of Motorama 2015
MegatRON, 30lber runner-up of Motorama 2015



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