A new tracking technique for mechanical angle measurement

Abstract

Resolvers and other types of sine/cosine encoders are used for measurement of mechanical angles. These devices produce quadrature signals in the form of sine and cosine of the unknown angle, and require converters to extract the angle from their signals. This paper describes a new converter based on an angle-tracking technique that employs synchronized reference and oscillatory signals. The tracking is based on quadrature PLL without using VCO, DAC, counter and look-up tables (LUT). The proposed method makes use of reference oscillatory signals to estimate the sine/cosine of the mechanical angle. The present method is simpler than the available techniques, and may be implemented easily using digital or basic analogue electronic circuitry. Beside its simplicity of implementation and its fast tracking capability, the proposed controller exhibits a good linearity and, when used with resolvers, offers the advantage of robustness to amplitude fluctuation of the transducer excitation signal. The proposed technique results were compared to a high resolution pulse encoder. This paper describes the proposed method, its simulation and experimental results.