The Robust Motion Control of a Robot Manipulator

Any feasible control of the multi-DOF mechatronic system has to face the problem of an extreme variability of the plant parameters as well as a strong influence of the variable external forces. The classical control methods are not able to manage such a complex and difficult task. One of the promising control approaches is the contemporary variable structure control (VSC) theory with its specific attribute – the sliding mode. In sliding mode, the system’s phase trajectory is robust and independent of the parametric and external disturbances due to reserve in power. Based on the VSC, the equivalent time sub-optimal control (ETSC) algorithm has been formulated for a single-DOF motion control system. The main benefits of this control are a simple control structure, the fastest possible and overshoot-free response and the insensitivity to any (parametric, signal) type of disturbances. One of the problems of VSC, the chattering elimination, has been solved via the reaching law approach. The aim of this contribution is the implementation of the prospective ETSC algorithm in the control structure of a multi-DOF robot manipulator. The robustness and accuracy of the control algorithm is verified and illustrated by the numerical simulation of a control system. Both the dynamic and the steady-state accuracy have been achieved despite the enormous influence of the mechanical coupling among the DOF’s of the robot manipulator. The simple implementation of the control algorithm, given by the linear combination of the mechatronic system’s directly accessible phase variables, represents an additional benefit of the presented method.