Speed Fluctuation Suppression by Model-Based Feed-Forward Control in Gimbal System with Harmonic Drive

Harmonic drive is usually installed in the gimbal system of single gimbal magnetic suspended control moment gyroscope (SGMSCMG) not only to meet the requirements on the volume and weight but also output large torque. However, its nonlinear transmission characteristics are also introduced into the gimbal system and make the output speed fluctuate, which will seriously affect the output torque accuracy of SGMSCMG. Torque feedback control is an effective technique for achieving high-performance control for the above-mentioned problem. Nevertheless, it is difficult to add torque sensors in the gimbal system. In order to obtain nonlinear transmission torque without torque sensors, a novel online modeling method based on the Lagrange equation is put forward. Besides, to restrain the main torque disturbance, the gear-wave torque model is extracted. According to the above-mentioned models, a model-based feed-forward control method with phase advance is presented. Plentiful simulation and experiments on an SGMSCMG are performed, and the results show that the load speed fluctuation can be effectively suppressed.