A composite QFT controller as a remedy for MIMO systems

In this paper, a new simple method to design a robust controller for a MIMO system is proposed. The work presented, combines QFT technique with the fuzzy logic controller (FLC). By joining QFT and FLC the advantages from both methodologies are achieved. This hybrid controller could be utilized to control a class of non-linear systems, where the plant may be expressed as a linear plant model with time varying parameters. In order to illustrate the utility of our algorithm, we present its application on a two degree of freedom robot link manipulator. Initially, a QFT controller is designed for tracking and disturbance rejection problems for each link. Then, an appropriate fuzzy controller is designed to compensate for the system dynamic coupling between the degrees of freedom. In order to optimize the performance of the fuzzy controller Genetic Algorithm (GA) is used. Next, nonlinear simulation for tracking problem in arbitrary paths has been carried out.