Composite Control Based on Feed-Forward and FISMC Method for Accurate Speed of Gimbal System With Harmonic Drive

In the gimbal system of single gimbal magnetically suspended control moment gyroscope (SGMSCMG), harmonic drive is usually installed to ensure the large output torque and reduce the volume and weight of the servo motor. Nevertheless, its nonlinear characteristics make the transmission torque fluctuate and decrease the performance of the gimbal system. The disturbance torque fluctuations can be divided into “gear wave torque” and “nongear wave torque,” and to suppress the different types of fluctuations, a composite control method based on model-based feed-forward and fuzzy integral sliding mode control (FISMC) method is proposed. The former method is adopted to restrain the gear wave torque. Then, for the rest of the disturbance torques, the FISMC with new dynamic sliding mode surface is put forward to enhance the robustness and improve the performance of the speed. Finally, the simulation and experiments are carried out on SGMSCMG to validate the effectiveness of the composite method. The results show that the torque fluctuation can be effectively suppressed and the performance of the gimbal system can be significantly improved.