Disturbance-observer-based robust control of a Serial-link robotic manipulator using SMC and PBC techniques

Abstract

Robotic manipulators deployed in automation industry require high speed with precision and accuracy to perform sophisticated control tasks. Whereas, the factors like highly coupled dynamics, internal and external perturbation forces, joint friction and parameter variations degrade the performance of the manipulator. Consequently, the need of an advanced control technique or more preferably combination of multiple techniques with the capability of handling disturbances has been increased significantly. In the present research, design of Disturbance Observer (DO) based control techniques for a 6-Degree Of Freedom (DOF) robotic arm is presented to eliminate the effect of uncertainties and disturbances and to enhance the robustness of both Sliding Mode Control (SMC) and Passivity Based Control (PBC). Results demonstrate that the proposed controllers precisely estimate the torque yielded by external perturbation forces and improve the trajectory tracking performance of the system, which results in comparatively high performance of robotic manipulator in terms of speed and precision.