Adaptive fuzzy controller for vehicle active suspension system based on traffic conditions

Vehicle ride comfort is a function of the frequency content of transmitted vibrationsto passengers from road irregularities. however, this frequency content varies with vehicle speedfluctuations, which occur under real traffic conditions. the design of an adaptive active suspension system,in order to simultaneously improve ride comfort and travel suspension under various traffic conditions,is addressed in this paper. for this purpose, using a full-vehicle model, with eight degrees of freedom,two separate fuzzy controllers are designed for front and rear suspensions. the parameters of the fuzzycontrollers are then tuned for various traffic conditions of a driving pattern, using a multi-objectivepareto-optimal solution. the optimization objectives are: the ride comfort index, evaluated according tothe iso 2631-1 standard, and the maximum suspension travel. simulation results prove that the multiobjectivefuzzy controller conventionally tuned, based on the constant speed driving pattern, results insimultaneous improvement of ride comfort, travel suspension and energy consumption. however, thiscontroller does not work optimally under all traffic conditions. on the other hand, the proposed adaptivemulti-objective controller not only results in optimal ride comfort and travel suspension under varioustraffic conditions, but also leads to a considerable drop in active suspension energy consumption.