Robust H-Infinity Decentralized Control for Industrial Cooperative Robots

In this paper, a robust H-infinity controller is proposed for industrial cooperative robots in which disturbances are taken into account for an appropriate controller design. Considering the disturbance affects the system performance is important to design an efficient control strategy to solve this problem. On the other side, robust control is necessary taking into account that disturbances, uncertainties and other unmodelled dynamics affecting the system performance for tracking control purposes. The main objective of this study is to control in a synchronized way several industrial robotic manipulators in a work-cell so the obtained results will be useful for different kinds of manufacturing processes. For this objective, the distributed dynamical model of the robot in the form of the Euler-Lagrange equation is established to derive the proposed control strategy that in this case consists of a robust H-infinity controller to deal with the disturbances in the robot manipulators and other kinds of uncertainties. For this purpose, a norm index is implemented for robust performance attributes of the system so in this way the controller is designed efficiently. One of the most important contributions of this study is that the position tracking of an object grasped by two or more industrial robotic manipulators is driven accurately. This can be done by obtaining the desired position and orientations of the end effectors of each robot and reducing the tracking error to zero as times goes to infinity while following a predefined path trajectory for the grasped object. Finally, a numerical simulation example and conclusions will be offered to validate and analyze the theoretical results obtained in this study.