Observer Based Sliding Mode Control for the Accurate Trajectory Tracking of Multi DOF Robot Manipulator

In this research, an observer-based sliding model control (SMC) has been proposed for the position control of five-degree-of-freedom (DOF) robot manipulator. Initially, proportional integral derivative (PID) control has been designed for the desired trajectory tracking and implementation of PID does not require the plant model. But tracking error in case of PID is higher due to non-linear nature of five-DOF robot manipulator. In contrast, SMC is robust against such non-linear systems. But the robustness of SMC is not guaranteed during reaching phase due to effect of perturbation on sliding surface dynamics. Therefore, in this research, a nonlinear extended state observer has been integrated with conventional SMC for complete perturbation compensation. Due to perturbation rejection, the sliding surface dynamics is only affected by the estimation error of perturbation. This phenomenon has guaranteed the stability of SMC during reaching phase. Simulations have been performed in MATLAB/Simulink. The results show that the proposed scheme has better trajectory tracking performance than the conventional SMC.