I have assembled two Mark III minisumo robots, YoshiMoto and TojoMoto, and enjoy programming them and otherwise experimenting (playing) with them.
Controller is a Microchip 16F877 that came with a "Bot Loader" that allows programming via RS-232 serial port so no chip programmer is required!
Obstacle/target detection is by the two front vertically mounted Sharp GP2D12 IR range modules.
Line following/edge avoidance is via 3 bottom mounted IR devices.
Processor power is from 9v battery mounted in the rear.
Servo power provided by 4 AA cells mounted on the bottom.
Servos are two GWS S03N 2BB modified for continous rotation.
Be sure to visit the Mark III web site. You can get into mini sumo for less than $100!
Click to go to the Junun.org website.