/* ----------------- Bumper for bioloid car --------------------------------- */
bumper:at (irC > 100)         // at obstacle detection
{
  wheels = 0 | sleep (500ms);  // stop and wait a bit
  wheels = -50 | sleep (1s);   // go backward
  wheels = 0 time:1s |        // stop smoothly
  wheels = 100;               // go forward
};

wheels = 100;                 // initial start
/* ----------------- Bumper for bioloid car --------------------------------- */

This should make your bioloid car go forward, stop before the first obstacle, go back for a bit and go again. You will have to figure how to make it stop. You must load bioloid_car.u before executing this script to have good result. (it's better to have a robot with 4 wheels to have a good look of the behaviour, see description of motors in bioloid_car.u).