A Novel Converter for Sinusoidal Encoders

The paper presents a novel and low cost method for determining the angle from sine and cosine signals generated by angular position sensors such as resolvers and sinusoidal encoders. The proposed scheme is based upon the use of the pseudo-linearity of sinusoidal signals around zero crossings. By inputting the transducer signals to a programmable weighted summer, and using simple trigonometry, an analog output made up of 16 pseudo-linear segments may be generated. These segments cover the full 360deg range of input angle, and are identifiable using a set of 4 generated binary outputs. The binary outputs enable crude measurement of the angle with a step of 22.5deg, while the analog output refines measurement by enabling precise determination of the angle with an overall theoretical error of 0.018deg. The converter was built using basic analog components. Experimental results generated with a revolver showed excellent agreement with theory and simulation.