There are two driving motors. One in the front and one in the back. It is 4 wheel drive but it cannot turn. The drive motors are not geared. The third motor is used to control the arm. that is geared down 1:5. The arm lifts up the front wheels, it drives forward to get the front wheels on the next step, then the arm goes back, and lifts up the back wheels and the robot drives forward to get the back wheels on the step.
The program is really simple. The PSP-NX-V3 remote control’s the robot. one joystick turns the drive motors, and the other moves the arm.