On variable-shift-based fault compensation of fuzzy controllers

In this paper we propose a fuzzy controller with the capability of compensating the influence of single stuck-at faults in membership functions. To cope with the faults in each antecedent part, the degree in a candidate regarded as a faulty function is exchanged for one of the following: 0, the degree in the next function to the candidate, and the difference between the constant and the degree in the next function to the candidate. To cope with the faults in the consequent part, several fuzzy variables are shifted, and then the fuzzy inference is executed with the membership functions representing shifted variables. Experimental results for a commercial controller show that the influence of any single fault deviating the normal deterministic output of the controller is compensated completely.