A Hall Effect Rotary Position Sensor

Rotary position sensors (RPS) currently are applied widely in engine management systems for throttle position sensing and are being considered for other applications such as drive-by-wire. The potentiometer RPS relies on contact between a resistive element and a wiper and thus has an inherent wear mechanism.

This paper describes a noncontacting RPS which is essentially a drop-in replacement for the present device. A linear output Hall Effect IC is key to achieving the required functionality, but it must be combined with a magnetic actuation scheme which provides a very linear and stable magnetic field as a function of input angle and packaging which provides long life and control of mechanical tolerances. Each of these design elements will be discussed.