Discrete-time adaptive control of robot manipulator with payload uncertainties

In this paper, a new discrete-time adaptive control scheme for controlling robot manipulators is proposed. The objective is to control position of a robot manipulator end effector in the presence of uncertainties caused by unknown fixed or time-varying payload. For simplicity, the unknown payload is considered as the only unknown factor and the data in use is sampled from the true continuous-time plant with constant fixed sampling interval. We estimate the payload according to the available history information and design a discrete-time adaptive controller based on the estimation of the external payload. The adaptive estimator adopted in the adaptive controller only uses one step history and is capable of fast adaptation. The simulation results demonstrated that the new controller can yield a satisfactory tracking performance in the presence of payload uncertainties.