Reinforcement learning-based fixed-time trajectory tracking control for uncertain robotic manipulators with input saturation

A fixed-time trajectory tracking control method for uncertain robotic manipulators with input saturation based on reinforcement learning (RL) is studied. The designed reinforcement learning control algorithm is implemented by radial basis function (RBF) neural network, in which the actor neural network is used to generate the control strategy and the critic neural network is used to evaluate the execution cost. A new non-singular fast terminal sliding mode technique is used to ensure the convergence of tracking error in fixed time, and the upper bound of convergence time is estimated. To solve the saturation problem of an actuator, a nonlinear anti-windup compensator is designed to compensate for the saturation effect of the joint torque actuator in real time. Finally, the stability of the closed-loop system based on Lyapunov candidate is analyzed, and the timing convergence of the closed-loop system is proved. Simulation and experimental results show the effectiveness and superiority of the proposed control law.