An Adaptive Gain Dynamics for Time Delay Control Improves Accuracy and Robustness to Significant Payload Changes for Robots

Time delay control (TDC) is a promising technique for robot manipulators because it is model-free, efficient, and yet, robust. Nevertheless, when a robot operates under significant payload changes, it is difficult to achieve satisfactory performance with a constant gain. To cope with this problem, several adaptive rules have already been proposed thus far, but they are less effective to significant payload changes, and parameter tuning procedures are too complicated. In this paper, we propose an adaptive gain dynamics that is more effective in payload changes and yet simpler to implement. Through simulations using a one-link arm and experiments using a whole arm manipulator with payload changes, the proposed dynamics was compared with the conventional TDC and two other existing methods. Simulation results show that the proposed algorithm can adapt to significant payload changes, achieving better accuracy than the conventional TDC. Experimental results show that the proposed method has consistently better adaptation capability than other methods, achieving significantly better accuracy. In addition, the proposed method is simpler to implement, having only one tuning parameter, whereas the existing methods require four or five such tuning parameters.