Servo - July 2009

hurting the bot if he blasted it. He held it up as if offering me a hors d’oeuvres. I yelled “yeah, hit it” which spurred him into action. He blasted the speed controllers a couple times with the fire extinguisher. It continued to flame and smoke for another half-minute or so. Finally, the extinguisher won and Terry looked up at me and said “The switch is on.” So, we took quick action and shut the switch off, which was moot at that point since any circuit that might carry current had burned away.

So, we carted the smelly thing outside and figured out what happened. Basically, this screw-up was a team effort. First of all, Steve and I hooked the batteries up backwards before the weigh-in. That’s right. We connected red to black and black to red. Simple as that. He hooked them up. I screwed them down and gave it the “thumbs up.” Without the switch on, this was not a problem, except when Terry lifted the bot off the scale and onto the cart, he stepped on the string used to power-up the rear drive motors, delivering 24 volts of bass-ackwards electromotive force to a pair of speed controllers.

They simply aren’t designed to handle a reversed power supply and, after a few seconds, gave in to the massive current running around in all the wrong parts of the speed controller. The speed controller probably didn’t carry the current for too long, but the capacitors exploded and the plastic case lit on fire. That’s what burned so persistently. From what we hear, photos of the burned speed controller were all over Twitter. So, this is how we established ourselves as the underdogs at BattleBots, Mare Island. Not only did we have a pink bot, we also had the bot that lit on fire. Many people were certain our competition was over. For the next two days, we heard lots of “Are you going to be able to compete?” and “Jeez, that’s too bad you came all the way out here for nothing.”

34 SERVO 07.2009

In reality, the overall impact on the machine was minimal. We found some melted copper, so it was a pretty hot fire, but the damage was limited to a small space immediately around the speed controllers which acted as a pair of $180 fuses, protecting any other parts from damage. Donald Hudson loaned us two speed controllers from Diesector; we soldered some new wires and that was that. The worst part was everytime we opened the machine up, we were hit by the nasty, lingering smell of electrical smoke. By the time we repaired everything, it was time to pick up the parts from the heat treating shop. That meant another trip down to the Oakland airport and back. Oh, joy.

As it turned out, we were the last professional team to make it through the inspection process, although our tardiness had nothing to do with the fire. Getting those parts late on Wednesday really set us back. We barely got them installed and ready for weigh-in on Thursday. In fact, I had to leave Terry to go through tech inspection by himself so I could make one last trip — my fourth — to the Oakland Airport to pick up my family.

Story 2: The Kids from Bradley University

On Tuesday night after dropping off parts from the heat-treater, we checked into the hotel and were heading out for a late snack. It was about 10 p.m. or so. As we drove away, we noticed a group of people gathered in the parking lot — some standing, some kneeling, some sitting on the ground. All were focused on something sitting on the ground, illuminated by a bright light. We immediately knew what it was. This had to be a college team working on a BattleBot. We made a U-turn to go see who it was. As we approached, we noticed a long extension cord running across the

parking lot. It was plugged into an outdoor outlet hidden in the landscaping of the hotel, providing precious power for the light and a hand drill that was clearly critical to the operation at hand.

Thus, we met the kids from Bradley University who provided us with multiple quotes that made our week, including “We just got funded a week ago,” “Our top-gun is asleep so we are trying to get something done before he wakes up,” “We made it entirely from found parts,” and “We weren’t sure the weld would hold so we put a bolt through it.” I might add it was a carriage bolt.

Anyway, these kids were way behind and working their butts off to get this bot finished. Unlike many of the teams there, they had no professional mentor. They had just started this thing about two weeks ago and it appears they went long on plane tickets and had little budget left for the bot — hence the “found parts.”

As we left them to go eat that night, it appeared hopeless for the kids from Bradley, but somehow we knew they would get it done and get that thing in the battlebox. For the next two days, we were really pulling for them. We kept a watchful eye, offered advice and tools whenever we could, and didn’t give up hope. We would have helped more, but they only had 48 hours before the tech inspection deadline and we weren’t familiar with any of the electronics they were running (they wrote their own “C” code for their speed controllers) so we were really afraid of slowing them down. They had to do this themselves, in their own way, and that they did. Those kids from Bradley were everything the college competition should be. I can’t wait to see their next machine.