USDE-Based Approximation-Free Control for Robot System with Prescribed Performance

This paper presents an unknown system dynamics estimator (USDE)-based approximation-free control strategy for robot system with prescribed performance. A prescribed performance function and associated error conversion mechanism is employed to guarantee the transient and steady-state error of robot system. Moreover, the USDE is constructed by a first-order low-pass filter operation with only one turning parameter, and then introducing to approximation-free control design to compensate the modeling uncertainties and unknown dynamics to further improve the tracking performance and reduce the controller complexity. The stability of closed-loop system is proved by Lyapunov and initial value theory. Simulations are carried out to validate the effectiveness of the proposed scheme based on a SCARA robot.