Non-linear Finite-Time Tracking Control of Uncertain Robotic Manipulators Using Time-Varying Disturbance Observer-Based Sliding Mode Method

Abstract

Abstract In this paper, a time - varying chattering - free disturbance observer - based position tracking control law of serial robotic manipulators is presented to track a reference signal in a finite time. The key idea is to employ a positive-increasing function associated with the control/observer objectives to improve the control performance. First, the model of an uncertain robotic manipulator is presented as the case study of the proposed strategy. Then, the time - varying form of the robotic manipulator model is obtained to provide finite - time boundedness using the first - order sliding mode method. Moreover, without any knowledge about the upper bounds of the uncertainties, a reduced - order observer is presented to estimate the uncertainties in a finite time. Subsequently, a disturbance observer - based finite-time position tracking control law is designed. The time - varying gains are provided to converge the position tracking error to a neighborhood of zero in a finite time. Finally, comparative simulations are presented to show the effectiveness of the proposed scheme compared to other existing strategies.