Design of fast fuzzy controller and its application on position control of DC motor

In this paper, a fast fuzzy controller which is implemented in an FPGA chip is used for the position control of DC motor. The technique of parallel architecture, direct computation and combinational circuit is adopted for the design of controller. In order to simplify the operation of input firing, we adopt the triangular membership function as the fuzzy sets for antecedent part. The firing strength of those triggered fuzzy rules are calculated through the parallel processing, when dealing with the fuzzy inference. For the consequent part of the fuzzy rule, the design parameters are stored as a ROM table so that it can be easily achieved for fuzzy inference. Meantime, a special divider circuit structure is proposed so that only one clock computation time is required for the operation of division. Then, the center average method is used to construct the defuzzifier. In order to demonstrate the correctness and efficiency of the proposed fuzzy control circuit, we combine the fuzzy controller with feedback circuit, comparison circuit as well as driving circuit and implement the whole controller in a Xilinx Spartan 3 FPGA chip. The digital fuzzy controller is applied to the position tracking control of DC motors. The simulation and experimental results show that the presented fuzzy control circuit is feasible.