Robust Control of Robot Manipulators Using Inclusive and Enhanced Time Delay Control

Abstract

Thanks to its simplicity and robustness, time delay control (TDC) has been recognized as a simple and yet effective alternative to robot model-based controls and/or intelligent controls. An inclusive and enhanced formulation of TDC for robust control of robot manipulators is presented in this paper. The proposed formulation consists of three intuitive terms: i) time delay estimation (TDE), inherited from the original TDC, for cancellation of mostly continuous nonlinearities; ii) nonlinear desired error dynamics (i.e., a ‘mass’-‘nonlinear damper’-‘nonlinear spring’ system) injection term; and iii) a TDE error correction term based on a nonlinear sliding surface. The proposed TDC formulation has an inclusive structure: depending on the gain/parameter set chosen, the proposed formulation can become Hsia's formulation; Jin's formulations, including a type of terminal sliding mode control; a sliding mode control with a switching signum function; or a novel enhanced formulation. Experimental comparisons were made using a PUMA-type robot manipulator with various parameter sets for the proposed control. Among them, the highest position tracking accuracy was obtained by using a terminal sliding desired error dynamics with a terminal sliding correction term.