Angular position measurement using resolvers together with a robust linearization technique

Abstract

Resolvers are used for both absolute angular and linear position sensing. A robust amplitude to phase converter is described for the determination of position from the sine and cosine output signals of the resolver. The scheme is based on a linearization technique for converting the co-sinusoids into a nearly perfect triangular signal from which the angle is determined using simple linear equation. Even though the amplitudes of the resolver output signals are proportional to that of the resolver excitation signal, the proposed amplitude to phase technique is robust to fluctuation and drift of the amplitude and frequency of the excitation signal. The theoretical absolute error of non-linearity of the converter is 0.0082 degree over the full 360 degree range. The converter may be implemented numerically or electronically. In this work, details are given for an implementation using basic analogue electronic circuitry The theory of operation and experimental results are given.