Adaptive Higher Order Sliding Mode Control for Robotic Manipulators with Matched and Mismatched Uncertainties

Abstract

Robotic manipulators have been extensively used in industrial and other kinds of applications. Thus, it is important to design effective control strategies for tracking precision for robotic manipulators. In this work, an adaptive higher order sliding mode control for a robotic manipulator with matched and mismatched uncertainties is proposed. Matched uncertainties occur when they are found in the input of the system and mismatched uncertainties are found in the system parameters. Hence, an adaptive higher order sliding mode controller is designed when both matched and mismatched uncertainties are found. Considering that uncertainties yield unwanted effects in the controller design, sliding mode control provides a suitable control strategy for robotic manipulators when extreme tracking precision of the end effector is needed especially in a reduced task space. The design procedure starts with the dynamic model represented in the Euler-Lagrange form considering the uncertainties of the system and then by implementing a Lyapunov stability method and selecting an appropriate sliding surface suitable control. Finally, adaptive laws are obtained taking into account the matched and mismatched uncertainties in the system model. As a numerical example, the proposed control strategy is validated for trajectory tracking purposes of a five bar linkage mechanism.