Friction Compensation Based on Time-Delay Control and Internal Model Control for a Gimbal System in Magnetically Suspended CMG

Nonlinear friction torque is an important factor affecting the angular velocity precision of a gimbal system in double gimbal magnetically suspended control moment gyro. To effectively eliminate the influence of friction torque and implement high precision control of the gimbal system, a method that combines time delay control (TDC) with two-degree-of-freedom (2-DOF) internal model control (IMC) is proposed. First, nonlinear friction torque of the gimbal system is estimated via time-delay estimation. Second, to independently adjust the tracking performance and disturbance rejection performance, and to enhance the robustness of TDC, 2-DOF IMC is introduced. Simulation and experimental results indicate that the proposed control method not only improves the compensation performance of the gimbal system with nonlinear friction torque, but also enhances the robustness and realizes the high precision control of the gimbal servo system.