A capacitive 4-turn angular-position sensor

Abstract

A robust, capacitive 4-turn angular-position sensor for automotive and metrology applications is presented. The main advantages of this low-cost system are its simplicity, speed, high accuracy (/spl plusmn/0.35/spl deg/), and resolution (/spl plusmn/0.02/spl deg/) over the absolute measurement range of more than /spl plusmn/720/spl deg/, compact sensor outlines, and insensitivity to dirt or condensation. The paper describes the working principle, derives the required relationships for computing the angular rotor position, and discusses measurement results obtained from a prototype sensor with small outlines (50 mm diameter and 8 mm thickness) used as a steering sensor in vehicles.