Instantaneous angular position and speed measurement using a DSP based resolver-to-digital converter

High performance servo control systems require the measurement of angular position and speed for improved accuracy, tracking, and feedback control. Resolvers are extensively used in such applications that demand instantaneous, accurate, and high-resolution information of these parameters for feedback control. In this paper, a scheme is presented for position and speed sensing using a resolver-to-digital (R/D) converter that is completely software implementable. The technique incorporates software generation of the resolver carrier using a digital filter and synchronous demodulation of the resolver outputs using the same. This allows saving of the costly carrier oscillator and associated digital and analog hardware for amplitude demodulation of the resolver outputs. Also, as the amplitude demodulation as well as the measurement of position and speed does not cause any time delay, the dynamics of the servo control that uses the scheme is not affected. Computer simulations and experimental results show outstanding performance at considerably attractive computational cost and hardware, demonstrating the effectiveness and applicability of the proposed scheme.