A Novel Approach to Enhance Roll Stability of SUVs by a Fuzzy Logic Controller

Rollover is one of the most dangerous events in driving Vehicles, specially the Sport Utility ones. This maneuver is the main reason for the majority of human and financial loss in transportation systems. The upcoming paper outlines the details as well as the plus points of a Fuzzy Logic Controller which is designed and simulated to reduce the rollover propensity of Vehicles, specially the ones with high center of gravity –mainly SUVs. A verified model for roll dynamics of the vehicle has been used for the fuzzy controller design [1,2]. This model predicts the roll, yaw and tire behavior of the vehicle fairly well. The simulation of the mathematical equations of the vehicle model has been done by writing MATLAB M.Files [1].The main contribution of this paper is designing a fuzzy logic controller to enhance rollover stability of the vehicle. To decrease the roll angle and roll rate in different maneuvering situations, Hydraulic actuators have been applied in the suspension systems along with the dampers with variable damping coefficient, such as magnethorehological dampers. By generating controlled forces in these actuators, and varying damping coefficient of the MR dampers, proper moments along the roll axis of the vehicle can be developed. This moment causes simultaneous decrease both in roll angle and roll rate in different vehicle maneuvers. Due to the Complexity of the system, ANFIS (Adaptive Neuro-Fuzzy Inference System) from MATLAB software has been selected to design fuzzy controller and to define membership functions of input and output variables. This approach is applied to express fuzzy rules as well. In the control system, the tire angle – – and vehicle velocity –V– are the inputs, and forces from the four actuators and the two damping coefficients are the outputs. The simulation results depict noticeable Progress in the response of the vehicle –roll angle and roll rate– both in the steady state and transient region.