Figure 13. Design of the forward movement sensor. Yes, that's my rendition of the grayhill rotary encoder.

Figure 14. Grayhill rotary encoder.

Figure 15. Forward movement sensor design seen from behind. A wheel turns the rotary encoder.

Figure 16. Forward movement sensor design seen from the side. This sensor is intended for attachment to the rear of the robot.

Figure 17. Snap lever switch used to detect when the robot falls. Very common device, but I need the kind with a 3 or 4-inch lever.

Figure 18. Snap lever switch mount design.

Figure 19. Theory for the lever bend.