Takagi-Sugeno fuzzy model of a semi-active suspension with a magnetorheological damper

Automotive suspensions are important systems in improving passenger comfort and vehicle stability. Magnetorheological dampers are actually being used intensively in vehicle suspensions, improving stability and comfort by changing the damping factor in milliseconds. The difficulty about MR dampers are the highly nonlinear characteristics and inherent hysteresis that turn the damper´s modeling in a complicated task. This research proposes a solution to the problem of semi-active vehicle suspension modeling through a type of Takagi-Sugeno (T-S) fuzzy model, not reported before, for a one-quarter-vehicle semi-active suspension with a Magnetorheological (MR) damper. The model has the advantage of being composed of linear subsystems, where all the linear control theory can be applied, thus further control work can be more accessible than the one applied directly to the nonlinear equations. Moreover, the new model contains all the nonlinear damper´s characteristics arduous to model and avoided in other reported work. The T-S approach breaks-down the nonlinear system into linear subsystems connected by fuzzy membership functions. Simulation work included herein, provides evidence of similarity among the differential equation model and the T-S model. The present research is an introduction to important opportunity areas in suspensions performance and other vehicle dynamics, considering that T-S approach can be extended to other subsystems of the vehicle.