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.