Nonlinear Tracking Differentiator Based Prescribed Performance Control for Space Manipulator

A low-complexity prescribed performance controller is proposed for motion tracking control of a space manipulator in this paper. First of all, a prescribed-time prescribed performance function is designed. Based on the function, the proposed controller is capable of guaranteeing the system transient and steady-state control performances satisfy the prescribed boundary constraints. Moreover, all tracking errors converge to stability domains before the user-defined settling time. A nonlinear tracking differentiator based on a hyperbolic sine function is adopted to estimate the derivatives of joint angles and reconstruct the angular velocity for the controller, which lowers hardware requirements for the controlled system to a certain extent. Without any time-consuming operations and model information, the proposed control scheme has a superiority in low computation complexity and robustness against model uncertainties. With the Lyapunov theory, the prescribed-time stability within prescribed performances of the closed-loop has been rigorously proven. Numerical simulation and the comparison with the traditional prescribed performance control demonstrates the effectiveness and superior performances of the proposed control scheme.