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|Target Environment||Locomotion Method|
|Sensors / Input Devices||Actuators / Output Devices|
|Custom IR proximity sensors||2 DC brush motors|
|Control Method||Power Source|
|CPU Type||Operating System|
|Time to build||Cost to build|
|About a month (a few hours per day)||$50|
|URL for more information|
|I built El Diabolic for the Critter Crunch competition in Denver Colorado. The event is basically like a sumo competition. Your bot must not leave a square 4' x 4' ring with a white surface and 1.5" black edge to help clue the robot it's nearing the edge. The goal is to shove the other guy off. In this event it's ok to try and damage your opponent. However at a weight limit of only 2 lbs it's hard to come up with something that's going to do much harm.
The robot is based on the Battle Bots series of toy robots. I stripped all extra parts off and used only the drive train. All my electronics were homemade. A lot of work went in the the sheet metal shell. The weight limit of 2 pounds proved to be a challenge and still have any "armor". The lower shell is out of .025" aluminum. The upper shell, where the electronics are is only .015". The front of the bot has a hinged ramp, this helped ensure the scoop edge always was against the floor. The 4 IR reflective floor sensors (QRB1114 from Dig-Key) were under the shell near each corner. The robot proved very adept at keeping in the arena, in spite of the more difficult square design.
The "360 degree" IR sensor board is a variation on the IR proximity sensor design concept by the Dallas Personal Robotics Group. In this case a single pic 16F628 is used to strobe the IR LED's. By using a transistor and a darllington array I could use the 628's hardware PWM line to run the pulsing frequency in the background with only one pin. A first for me was using a 74LS164 serial to parallel chip to expand my I/O capability to indicate via visible LED's that an object was seen at a sense angle. This helps to indicate the sensor system is working. Then the data is sent serially to the main processor.
Initially I had some difficulty because the light would leak too much from the very high power IR LED's After lots of black heat shrink that would follow the leads all the way to the PC board it appeared fixed.