Robust velocity-regulation control of gimbal servo systems using a predictive comprehensive disturbance observer

A robust high-precision velocity-regulation controller is researched for gimbal servo systems (GSSs) in this paper, which aims to mitigate the impact of multiple adverse factors, including both the internal time-delay characteristics and external time-varying disturbances. First, to enable a more accurate estimation and compensation against disturbances of multifrequency-band under input time-delay, a generalized system modelling of GSS is developed with detailed classification and description of different uncertainties. On the basis of such a generalized model, a predictive comprehensive disturbance observer (PCDO) is designed to accurately predict both system states and multiple disturbances with multi-frequency-band. Based upon the predictions provided from PCDO, a composite controller is further constructed to ensure the closed-loop stability of GSS. A rigorous robust stability proof of the closed-loop system is presented. Simulation analysis under various uncertainties are conducted to thoroughly validate the efficacy of the proposed PCDO-based control approach.