Tracking control of a manipulator under uncertainty by FUZZY P+ID controller

One of the most important manipulator operations is the control of the manipulator to track a given trajectory. Most commercial robot systems currently are equipped with conventional PID controllers due to their simplicity in structure and ease of design. Using PID control, however, it is difficult to achieve a desired tracking control performance since the dynamic equations of a mechanical manipulator are tightly coupled, highly nonlinear and uncertain. In order to improve the tracking control performance under uncertainty, this paper presents a new hybrid control scheme for the manipulator, which consists of a fuzzy logic proportional controller and a conventional integral and derivative controller (FUZZY P+ID). In comparison with a conventional PID controller, only one additional parameter has to be adjusted to tune the FUZZY P+ID controller. The proposed control scheme has been implemented on a direct drive two-link manipulator. The outlined experimental results on tracking control under inertial parameters' changes demonstrate the effectiveness and the robustness of the new FUZZY P+ID controller. (C) 2001 Elsevier Science B.V. All rights reserved.