An Improved Position Self-Calibration Method Based on Multi-Harmonics Estimation for Resolver-to-Digital Conversion

The position self-calibration strategy is beneficial in decreasing the position deviation of the resolver-to-digital conversion (RDC), thereby improving the pointing accuracy of the servo system applied to the satellite optical payload. However, existing self-calibration methods primarily focus on the second harmonic caused by a single non-ideal factor, neglecting the fundamental and higher order harmonics in the typical position deviation resulting from the coupling of multiple factors. To address this issue, an improved position self-calibration method based on multi-harmonics estimation for the RDC is proposed in this paper. First, the position deviation model under multi-factors coupling is established. Second, the speed deviation caused by the position deviation and its integral signal is estimated by the speed observer. The integral signal is input into the multi-harmonics observer, simultaneously estimating the DC, fundamental and higher-order harmonics components, while also analysing the convergence conditions of the observers. Finally, the position deviation is estimated by combining the estimations of harmonics, and the compensation lookup table of the position deviation is established. Simulation and experimental results show that the calibrated deviation is reduced by 89.4% relative to the original deviation. Compared with a comparable method, the proposed method improves calibration accuracy by 27%.