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:
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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.

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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!

And We Shall Call it... Razor Wind

Last time we discussed the improvements over Safety Razor v1.1. Where are we now? Well in Atlanta Maker Faire build blitz, I built the entire thing. Lets see what images I can scrounge up.

Seeing as how there were 1-2 weeks until the event, I broke down construction into two main parts: frame and hubmotor. Ive attempted building a hubmotor several times, but never finished them. I'll be paying special attention to the motor this time.

First came the turning of the wheels. The front wheel included two facing operations and two counter boring operations for bearing recesses. The shaft was also turned from a round of 1-5/8" billet.

A stator was salvaged from a Turnigy motor. It measures 52.84mm in diameter and is planned for about 20-25 turns a tooth as described in the last post. The shaft was machined by our resident expert machinist Stephen Culpepper. A light application of glue held the motor in place.

Ever since I learned how to properly set my working zeros, my parts have come out drastically more precise with better finishes. The endcaps were First waterjet machined from 5/8" plate and then turned on the lathe. While mounting the plate on the cutting table, I realized I ordered 3" wide flat for a 3" dia part. 

Luckily, I am a boss. The advantage of waterjet cutting first allows me to add through holes and a tentative bore. This way, I wont have to mount the disks on a rotary table to drill the holes. 

Magnets installed. Each strip is actually composed of two magnets for a total of 28 magnets. It works, but is irritating for slow settling glue because the field on the edges repel each other.

I also spent this moment to waterjet the magnet flux rings. These were cut from 1/2" A-36 plate, epoxied together to make a total stack of 1.5". Anyway, back to the endcaps.

Partway complete.

These are probably the best pieces I have turned in my entire robotics career. The only surface I wish I could have treated were the outer edges of the flange as it still has the water jet's frosted edge.

Two endcaps with bearings were press fit in the bore of the wheel. Inside lay the waterjet style flux rings. A waterjet scrap of 3/32" polycarbonate served as a sensor mount. I figured this convenient in case I wanted to manually advance the timing of the motor.

Glued...

Wired...

Installed.

The rather large and wide front wheel of the scooter would need a custom set of front forks to account for the 2x width. Luckily, the Razor A2 frame has a "shock mounted front" aka block of rubber and hinge. I took this opportunity to create a custom mating piece that has shock absorption and a wider section. 

A block of aluminum was first water jet machined to rough dimensions and finished on the mill. The raised section in the back limits the backwards travel of the hinge, the 5/16" hole is the hinge point, and the 10-32 tapped holes mate to parallel plates to facilitate the wheel.

The frame went together as quickly and easily as the old one did. This time I spent time to open up the width of all the slots by .005" such that I would have to do less sanding later. I also decreased the kerf compensation from .015 to .012 on the waterjet. The combination of both along with the use of a scrapper produced a very clean tabbing. I don't have to hammer anything together, but instead they press lightly together. The appropriate frame parts were mill mounted and drilled as needed. First a spot drill, and then a sharp 3/32 to finish it up.

Repeat. The frame at one point in time looked like this:

The main rails were together and it was beginning to take shape. A day later:

It looks much more sleek than Safety Razor. Looking at it, you could barely tell it was electrically assisted at all. Let's compare it to Safety Razor:

By late Friday evening before the Maker Faire, the lot of us grew lazy. I was intending to waterjet the throttle pieces from 1/4" Aluminum, but Charles convinced me to start rapid prototyping the remaining parts.

 Among the throttle, the fan covers and charge plug covers were also printed.

The final product! Now presenting Razor Wind!

So how did it work? Well it worked well for about 20 minutes before failures began. The main problem lay in the motor. The motor seemed under specified for the amount of load required. I decided to opt for 20 turns of 20ga wire because I wanted speed, originally thinking the speed controller could throw enough current to through the motor to meet the requirements dictated by the sensors. However, this caused the motor to heat up very quickly. The heat, combined with the motor torque broke the glue joints and allowed the motor to rotate around the shaft. This effectively ripped wires apart internally and shorted some connections. The motor went up before the Maker Faire.

Razor Wind still served as a great display item along with the still functional Safety Razor. We also had some surprise scooter-wielding guests.

I have since then rewound the motor with 22ga wire and machined a small nail to act as a roll pin for mechanical locking. I am convinced the real solution would be to increase the voltage or overall size of the motor. My next solution, involves some number of these: