Integrated Capacitive Wheel-Contact Sensors

A low-power capacitive proximity sensor has been developed as a prototype of wheel-contact sensors for a small robotic vehicle. The sensor is integrated into a wheel and consists of only a few components that add very little mass to the wheel. The output of the sensor serves as an indication of contact with (or proximity of) the ground; this output can be used as feedback for a vehicle control system. An important aspect of the circuit design is the use of capacitive (instead of slip-ring) coupling between the sensor circuit and associated external circuitry; in comparison with a slip ring, a capacitive coupler is more reliable, less electrically noisy, lighter in weight, and less mechanically complex.