Modeling of the front end of a new capacitive finger-type angular-position sensor

Abstract

A robust capacitive finger-type angular-position and angular-speed sensor for automotive and metrology applications is presented. The advantages of the capacitive sensor principle are simplicity, high response speed and resolution (/spl plusmn/0.04/spl deg/), compact sensor outlines, and insensitivity to dirt and condensation. Additionally the presented finger-type geometry allows easy mounting and replacement. The paper describes the working principle, the design and the layout of a prototype sensor. It models the front-end topology and derives the transfer function of the input circuit. The required relationships for computing the angular rotor position are presented, and measurement results obtained from a prototype sensor are discussed.