A hierarchical fuzzy approach to supervisory control of robot manipulators with oscillatory bases

The research focuses on the issue of controlling a manipulator attached to a deployment, which typically exhibits compliance due to its mechanical nature. The problem is generalized as a motion control of a robotic manipulator attached to oscillatory bases. Due to the complexity of this problem, we decompose the control task into two subtasks and distribute them over two different levels. In the design of hierarchical fuzzy control structure, the lower level controllers take into account each subsystem ignoring the interactions among them, while the upper level controller handles subsystem interactions. The upper level coordinator to deal with the model reduction error and makes the supervisory decision to the lower level. Moreover, the supervisory fuzzy rule set is used to adjust the correction factors of the hierarchical fuzzy controller to achieve better performance. Consequently, it is shown that the proposed control model offers several implementation advantages such as less on-line computation time, reduced effect of overshoot and chattering, and a fast convergent rate in simulation. The results of this study can be feasible to various mechanical systems, such as mobile robot, gantry cranes, underwater robot, and other dynamic systems mounted on oscillatory bases. (c) 2007 Elsevier Ltd. All rights reserved.