FPGA based real-time adaptive fuzzy logic controller

Fuzzy logic based control systems provide a simple and efficient method to control highly complex and imprecise systems. However, the lack of a simple hardware design that is capable of modifying the fuzzy controller´s parameters to adapt for any changes in the operation environment, or behavior of the plant system limits the applicability of fuzzy based control systems in the automotive and industrial environments. The design and implementation of an FPGA based fuzzy logic controller, that allows real-time modification of its membership functions and rule base is introduced in this paper. The development of the controller´s architecture is carried out on a National Instruments Intelligent DAQ board (PCI-7833R) with a reconfigurable Xilinx Virtex-II FPGA. The proposed design combines the performance advantages of existing static FPGA based fuzzy control architectures, with the flexibility and ease of implementation of conventional micro-controllers and general purpose processors. To test the efficiency of the controller and its ability to stabilize a highly dynamic system, a semi-active suspension system was developed. Simulation results for the proposed FPGA controller showed a 56% characteristic enhancement over the standard passive suspension system.