A novel low-cost noncontact resistive potentiometric sensor for the measurement of low speeds

A novel low-cost sensor system for the measurement of low angular or linear speed is presented. The sensing element consists of a noncontact resistive potentiometer. The applied sliding electrode does not make mechanical contact with the resistive layer. The processing circuit consists of a very linear oscillator which converts the position quantity to a period-modulated signal. This signal can be directly read out by a microcontroller. A novel algorithm is presented which can eliminate or strongly reduce the influence of the many nonidealities, and which results in a short measurement time. The resolution of the low-cost angular speed sensor system is about 8/spl times/10/sup -2/ r/min in a measurement time of only 80 ms. The angular range is limited by the potentiometer geometry and the finite size of the sliding electrode, and typically amounts to about 270/spl deg/. The sensor system also indicates the moving direction.