Abstract—In this paper, a new and simple method to design a robust controller for a robotic system is proposed. The presented work expands on previous research into the uses of robust control design methodology. Specifically, we combined quantitative feedback theory (QFT) with the fuzzy logic controller (FLC). This combination takes advantage of both methodologies. The hybrid controller could be utilized to control a class of nonlinear systems, where the plant is expressed as a linear model with time varying parameters. In order to illustrate the utility of our algorithm, we apply it to a robot arm having two degrees of freedom. A desired trajectory is specified. First, a robust QFT controller is designed for each link of the robot arm. QFT controller is used to follow the desired trajectory. Next, an appropriate fuzzy controller is designed to alleviate the complexities of the system dynamics. Lastly nonlinear simulation for tracking problem in an arbitrary path has been carried out which indicates successful design of QFT and Fuzzy controllers.

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