This robot is completely guided everywhere by whistle, much like the “Golden Sonic Toy” made in 1957.
When switched on, the robot moves in the direction indicated by the illuminated arrow on the front drive wheel mechanism. When the whistle is blown, the front wheels rotate. Stop blowing the whistle and the machine will resume moving in the direction indicated by the arrow.
The drive motor in forward mode moves the robot, in reverse mode it rotates the drive wheel assembly. To make all this operate, two “one way bearings,” a slip ring, sound detector and SPDT relay are required.