GMX Part 2: Combat!

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.

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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

AMMF: It's Robot Fighting Time!

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!

Return of the Roboteer

After exploding over $160 in brushless ESCs, I've decided to take a break from electric vehicles for the time being and get back to the finer points of combat robotics. Last year I had begun the development of a nifty angle-armor design with an eggbeater for a weapon. I tried to utilize the full capabilities of the Invention Studio, but I realize now I was missing the mark in design. So with that said, a few modifications:

In light of my new fondness for systems controls, this new version will be called "Dominant Mode".

New design features include:

• Center support wall now used tabs instead of slots. # of screws reduced from two to one. This change added alignment benefits and more supporting material. The original design used only slots which meant the vertical misalignment was possible if the end-drilled holes were not exact. Using only one screw leaves more 2024 Al frame rail.
• No more b16 gearmotors! While I am still using the indirect drive method (dual belts), I dropped the custom B16 gearboxes because the tolerances were too tight. Instead, I created a frankenbox from B16 motors (reasonable KV but high KT) with the "Ebay motors" gearboxes (10:1 ratio). With 15k rpms at 12v on a 10:1 gearbox, I should be getting 1850 rpms at each wheel at 14.8v. That is  FAST!
• New drum design. That right, I said drum. Even with the 8+ hours of machining that block of A2 for the eggbeater, I just cant ignore the benefits of the drum. More difficult to make, but stronger overall, higher MOI, and more geometrically effective against vertical disks. It also allows me to experiment with my new drum design, detailed below.
• No more Scorpion HX. Unfortunately not everything can become a positive. Due to bad dimension spec's by turnigy, I no longer have space in the robot for my scorpion HX. My alternatives are using the BB3-9 ESCs or the HMC 3-9 ESCs. While essentially the same, one doesnt suffer from transient neutral zone drift...

So once again I began building without documenting my steps (building gets too exciting to grab a camera, ugg).

Began by machining my wheels. That is .75" dia case hardened Al shaft wit ha groove for my urethane belts and a 3/8" bore for my bushings. A 1/4" dowel pin will press into my main frame rails and act as shafting for these guys. Like so:

Pretty sweet eh? I might be able to drive it soon! The urethane belts were custom made using cord stock from mcmaster-carr. Just hold the ends over an open flame and push them together. Removing from flame, the urethane will cool and fuse together. Then clip off the excess.

The actual tread come from a 3/8" sheet of 60A durometer SBR rubber. WATERJET GO!

A nice little feature to mention about the new frame rails are the tabs for the top and bottom plate. Additional rigidity and no quirky misalignment. Perfect every time! Here are the top and bottom plates:

The black plate is the top made from anodized 5052 Al and the bottom plate is 7075 Al (nothing but the good stuff!). Both are approximately 1/32" thick. I am really looking forward to engraving on the top. I'll pick some rather aggressive exponential to drive the "Dominant Mode" point.

On the bot

Over the weekend, I took the liberty of wiring up the robot. Knowing how little space I had remaining, I ended up with the electronics cube.

The bus caps on the weapon esc actually had to be resoldered to the board in a strange parallel combination. I had a chance to try my p0w3r bus idea again with the escs. The entire assembly is stuff! 10 points to the person who can find my receiver.

In the bot. I later surrounded all the surfaces with foam padding. ESD of course.

So some of you may be wondering, what will happen to that champion bot Cake? Well since I didn't end up using my B16's, scorpion HX, orange RXs, or my TP 3s 800mAH lipoly, I could very well reassemble! But with a special modification...

Muahahaha...

Next time, videos of driving and drum components build!

p0w3r Drive: Three Cheers for the Arbor Press

Expecting to do some research this afternoon; did not exactly pan out. So I elected to say on west campus and do some wheel work.

The other night I tried boring one of the 5" 30A durometer wheels..



... but then it exploded. Synopsis tells me there are air pockets in the core material, and my feed rate was too high, which caused the bit to grab and toss the wheel. 300 fine for aluminum, not so much for plastic

Today, I went for round two. Turned the lathe into high gear, 455 rpms and lots of non-cinnamon (unfortunately) Tap-Magic. Like magic, we now has a properly bore'd wheel.



Posing with the stator for comparison.



Speaking of which, I put the stator hub back on the lathe and reduced part of the center mass. This would make internal wire organization easier by allowing more internal wiggle room.

Decided to tackle the flats next. Unable to find the binding screw for the large Vertrax mill, I went over to the ME2110 labs to barrow their cute mini mills.

OH GOD THE STORIES ARE TRUE! These mills really suck. I was making passes through aluminum like a pro, when I realized the mill axis started drifting. I felt like a inverted pendulum balancing robot, constantly adjusting to changes in my environment.




Either way, I finished the task, and with a half decent finish as well. Next chance I get, I'm asking my fellow studio ULI's how to tighten the collets on the Vertrax.

While I added a roll pin groove using a hacksaw, I finished preparing the waterjet, post-dredging. I want to say it would take about an hour to fill the tank manually, but since I filled it over the span of two days, nobody remembers. Similar is to be said about the number of licks it takes to get to the center of a Tootsie Pop.

Waterjet filled, cutting commences. I cut the magnet ring laminations from a 1/4" plate of A-36 mild steel, end caps from 1/4" 6061 Aluminum, and the spacers from 1/8" polycarbonate.




Ironically, the material for the spacers was the sheet of polycarbonate that was stolen from me last semester. Hmmm, how circular.

There was drilling, tapping, countersinking, and a big hand from the enormous arbor press. I declare the hubmotor mechanically complete. That leaves us in this current state:





Gathering inspiration from Iron man 2, I proceeded to wind the motor. 23.5 turns of wire per tooth, dLRK style for space savings.

Lesson learned: If you wind with anything 20ga or lower, wear gloves or wrap cloth tape around your fingers. Your writing hand will thank me later.



Completed stator winding, terminated with a Wye connection. I'll wait to see if this motor actually works before adding the sensors. This means the possible run date is the 23rd of Feb, seeing as how UPS managed to butcher the shipping of the box of magnets (routing delays).

Until then, cheers.

Safety Razor Safety Advisory Report

So it's been a month since I butchered a child's Razor scooter and shoved a electric bike motor system into it. Let's hear some results!

I am able to use it for inter-campus transportation with about 50% capacity drain for a full day.



That's acceptable. Especially since it is probably mostly burst amps from accelerating. Voltage has yet to drop below nominal 22.2 (for a 6-cell lipoly). I still regularly monitor the pack for increased volume, but nothing vile has arisen. The picture above shows post-charge results. We have a 66% drain over an extended run time (I had group projects across campus that evening). You'll have to excuse my camera. No flash superimposed the words "END" and "BAL" to create the illusion of "BAD" on the LCD screen.

Over a period of time, I discovered my ground clearance to be steadily decreasing. My predictions have been reaffirmed. The amount of metal removed from the original frame, combined with the hastily designed frame extensions drastically reduced the integrity of the structure. I disassembled the frame this holiday break and discovered the fracture points to lay just as I had predicted: the region where aluminum and polycarbonate met.



All of this could have been avoided by starting with a single piece aluminum frame extension. Thankfully, I am still a ULI, and speedy metals is having a 10% holiday discount until January 31. Therefore, bring in the upgrades!



From the image, you can see the back end remains virtually the same. I rotated the motor mounting holes so that the centerline from the motor shaft to the wheel deadshaft were in line. Originally, the sprocket would rub against the spacer with left from some interestingly deep erosion marks as illustrated in the picture below. Undamaged spacer included for reference. I hope you know what a hex bolt is supposed to look like.



The majority of the changes were made to the front half. This iteration does away with the original scooter frame. It was far too troublesome modifying the frame to the design and it bore little fruit other than comedic value. This body is serious business. Slots and tabs everywhere. The accessible panel has been moved from the bottom to the top. This is because repeated ground scrapings sheered screw heads which made it a pain to disassemble. Speaking of bottom plates, a UHMW skid bar will be added to take the blunt of aggressive gutters and sidewalk ramps. On top of all that aluminum will most likely be a sheet of 1/16" garolite. Just something to cover the large gaping service channel and be pretty. If it is garo, I might even consider laser engraving a graphic into the center of the deck. Gettin' fancy now...

Of course, this frees up about 2-3" of space in the scooter body, not to mention the extended width and height. This means I can opt for a BIGGER BATTERY or protection to my current pack. Both would be nice, but I may push for the larger battery in preparation for the next advancement in campus transportation: MTD (to be described in detail later).

Lots of great material coming up (but its late, and im lazy).
-BBots
-MTD
-Hardbord

I Added a Scooter to my Motor

Here's the story:

On Black Friday, I bought this Razor-A scooter for $17. Now why would I waste my money on a scooter built for 5 year-olds(+)?

So I could concatenate one of these with it:

That is a 24v, 400W Kollmorgen brushless sensored motor that weighs 5-6 lbs. It is made for electric bicycles and weighs more than the scooter frame. Finally, it is larger in diameter (~5") than the scooter wheels (98mm ~ 4").

Needless to say, this is a project of epic disproportions! Yet, I still want to be manageable so I can actually use it in my cross campus commutes. Here's the game plan:

I am going to make an extended under body to house the batteries and extend the length so I can have some foot space and motor mounting provisions. Tentative model:



The wheel will be chain driven (#25) at about a 2:1 ratio. The frame thickness about the body is 1.25". The spoiler on the back is not for down force but rather acts as a foot rest because the frame is so small (seriously, the frame can only fit one of my feet lengthwise). Everything has slots, T-nuts, and delicious waterjetting. This will require major frame modifications too. The rectangular extruded frame will need to be cut on the bottom to allow the battery to hide inside. Also, some of the flanges on the side will need to be cut off because I need a flat surface to bolt the aluminum plates. Each operation removes from the structural rigidity of the frame which worries me.

Now one decision I am regretting is making the front segment from 1/4" polycarbonate. Why on earth would I make such an important part from (thin) plastic? Well because I already had it on hand. I'm in college and money doesn't grow in trees. I am worried about it bending or snapping somewhere in that region. I would run FEA on the part, but I have no idea what grade of shit-luminum Razor uses on their scooter.


Lots of pretty parts. The front of the undercarriage is made already from pre-existing plates of polycarb. Longpack and Macromotor wait in the wings...


And here is the integrand. One razor scooter awaiting cosmetic surgery...

Anyway, A lot of building happened in the span of three days and magically the project is done! My phone actually ran out of batteries so I couldn't take any build pictures. :(

Sorry folks, all you get are end result pics and video!


Sitting pretty by my fridge(s).


The throttle is a 5k pot with a shaft hub from Servo City. I should enclose those wires sometime soon.


The rear module. You can tell it is slightly different from the original CAD because I had forgotten which direction the motor spun. This made for a very disappointing initial ride test.


Closeup of the slot and tab T-Nut design. I experimented with the tool offsets on the waterjet such that it is a perfect slide with higher quality cuts. Are you proud of me Charles?


The underside. Notice where the metal becomes polycarb. I expect this region to be first to fail because it sits in between the two wheels and theoretically supports the entire rider's weight.

It has more than enough power to flip a rider over and reaches a top speed of ~20mph (calculated as 3500rpm on a 98mm wheel). It is amazingly unsafe...

... so I shall call it, "Safety Razor"