Finite-Time Trajectory Tracking Control for Free-Flying Flexible-Joint Space Robots With Performance Constraints and Actuator Saturation Under Sudden Disturbances

Abstract

For the trajectory tracking control of a flexible-joint free-flying space robot (FFSR) with performance constraints and actuator saturation under sudden disturbances, a finite-time adaptive controller (FAC) is proposed. In the framework of the finite-time command filter backstepping technique, a novel finite-time anticipatory activation anti-saturation (FAAA) is developed to cope with the actuator saturation. To ensure the transient performance of trajectory tracking under sudden disturbances, a novel form of asymmetric fixed-time boundaries (AFB) is designed based on an improved asymmetric logarithmic barrier Lyapunov function (IALBLF). In the convergence stage of AFB, the trajectory deviations caused by sudden disturbances are suppressed by the design of a translational single-peak boundary, while during the steady-state stage of AFB, an adaptive boundary compensation term is proposed to autonomously adjust the constraint boundary based on the tracking error. Finally, the effectiveness and superiority of the proposed control scheme are verified by simulations.