A Novel Hybrid Proportional Derivative/H-infinity Controller Design for Improved Trajectory Tracking of a Two-Link Robot Arm

Abstract

In this work, a hybrid control strategy integrating proportional derivative and H-infinity control method is proposed for a serial two-link robotic manipulator. The aim of this research is to achieve an improved trajectory tracking performance of the robot arm. The H-infinity controller achieves high performance and robustness in the presence of disturbances and uncertainties, such as unwanted overreaction caused by the derivative control's quick response times, while the proportional derivative controller stabilizes the nonlinear manipulator system. Simulation results using matlab shows that, the proposed hybrid controller, which integrates the advantages of both proportional derivative and H-infinity controllers, has the lowest rise time for the second link, the lowest settling time for the two links, the lowest peak time for both links and the fastest decay of the error response. In addition, the hybrid control scheme also has the lowest mean square error value, with 53.3% improvement over H-infinity controller and 91.8% improvement over proportional derivative controller, indicating improved trajectory tracking performance when compared to pure proportional derivative and pure H-infinity controllers, respectively. It was also discovered that, the hybrid controller has the lowest Integral Absolute Error (IAE), Integral Square Error (ISE), Integral Time Absolute error (ITAE) and Integral Time Square (ITSE) for the second link, while the error values for the first link are fairly okay, showing the superior performance of the hybrid controller above PD and H-infinity controllers respectively.