Adaptive PD-SMC for Nonlinear Robotic Manipulator Tracking Control

摘要

This paper presents an adaptive and robust control scheme, which is based on Sliding Mode Control (SMC) accompanied by Proportional Derivative (PD) control terms for trajectory tracking of nonlinear robotic manipulators in the presence of system uncertainties and external disturbances. Two important features make the proposed control method more suitable for tracking control of robotic manipulators in comparison with SMC. One of these features is the model free nature of proposed control, which implies avoiding the need to determine dynamic model of the controlled system. As a second feature, control and adaption technique used in the proposed method cancels the need for determining the upper bounds of uncertainties. It should be emphasized that SMC requires the dynamic model of the system and prior knowledge of upper bound of uncertainties. Lyapunov theory is used to prove stability of proposed method and a four link SCARA robot is selected for demonstrating efficacy of the proposed method via simulation tests. Simulation tests are utilized to compare the proposed method with conventional SMC in terms of tracking control performance and cumulative error. Results have revealed significant improvement in both aspects.