For local control we use C-Control units from Conrad. They include a Motorola microcontroller HC05 running at 4 MHz with 8 KB EEPROM for program storage, two pulse-length modulated outputs for motor control, a RS-232 serial interface, a free running counter with timer functions, analog inputs, and digital I/O.The units are attached to a custom board containing a stabilized power supply, a dual-H-bridge motor driver L298, and a radio transceiver SE200 working in the 433MHz band. The robots are powered by 8 + 4 Ni-MH rechargeable mignon batteries.