Determination of scaling factors for fuzzy logic control using the sliding-mode approach: Application to control of a DC machine drive

In this paper, a new approach to define the optimum values of the scaling factors for a fuzzy logic controller, based on the sliding mode theory, has been proposed. Indeed, these factors are chosen in such a way that the trajectory in the phase plane is always attracted by the main diagonal of the fuzzy matrix and slides on this line. This approach was first tested in simulation to control the position of a permanent-magnet direct-current machine drive and then implemented on a low-cost 16-bit microcontroller. Furthermore, the scaling factors are tuned in function of the distance between the reference and the output in such a way as to cope with the discretization of the lookup table stored in the memory of the microcontroller. This algorithm has been successfully applied on an advanced test bed, which allows mechanical configuration changes.