Extracting Accurate Position from Resolver Based on ESO and Notch Filter in Gimbal System

In the gimbal servo system, there are some systematic position errors in the raw position obtained by the resolver-to-digital conversion system of the resolver, and that can degrade the performance of the system. This paper conducts a study on the method of calibrating that error. Considering the lack of the space in the system and the impracticality of installing another accurate position sensor to compensate the resolver position error, a neoteric self-correcting compound method on the basis of the discrete extended state observer (DESO) and notch filter are designed to estimate and calibrate the raw position error of the resolver. According to the raw position, the accurate speed can be obtained by DESO. Then, the harmonics in raw signals can be restrained by the notch filter. At last, the position error of raw signals can be acquired and written to the control procedure to calibrate the raw resolver position. Finally, the compound self-correcting method proposed in this paper is demonstrated by plentiful simulations. It is easy to be implemented, and the raw position of the resolver could be effectively enhanced.