Experimental and Analytical Delay-Adaptive Control of a 7-DOF Robot Manipulator

Abstract

We study the analytical and experimental trajectory-tracking control of a 7-DOF robot manipulator with an unknown long actuator delay. In order to compensate for this unknown delay, we formulate a delay-adaptive prediction-based control strategy in order to simultaneously estimate the unknown delay while driving the robot manipulator towards the desired trajectory. To the best of the authors' knowledge, this paper is the first to present a delay-adaptive approach for a nonlinear system with multiple inputs. Through Lyapunov analysis, we first obtain a local asymptotic stability result of the proposed controller. Then, through the results of both our simulation and experiment, we demonstrate that the proposed controller is capable of tracking the desired trajectory with desirable performance despite a large initial delay mismatch, which would cause non-adaptive prediction based controllers to become unstable.