Drive

Motion Control Unit

Fig. 1: Motion Control Unit

The drive mechanism is in the base of the chassis and is equipped with a differential drive. Two DC-motors with a planetary gear are used to move the robot. The drive motors also contain a gearbox with a gear transmission ratio of 14:1 and a magnetic encoder for the speed and positioning control (shown in Fig. 1). A special controller at the main board is implemented to guarantee the exact execution of the movement.

Odometric Navigation

Fig. 2: Odometric Navigation

The principle navigation is based on odometric navigation. As shown in Fig. 2 the robot will measure the increments of the left and the right wheel cyclically and calculate the differential path ds and the angle φr. With these variables the exact x- and y-position can be calculated.
At the beginning the x and y coordinates and the starting angle must be known and these values are stored in the microcontroller.