A Tire Work Load (TWL) Based Controller for Active Independent Front Steering System (AIFS)

Vehicle Handling performance depends on many parameters. One of the most important parameters is the dynamic behavior of the steering system. However, steering system had been enhanced thoroughly over the past decade where Active Front Steering (AFS) is now present and other system as Active Independent Front Steering (AIFS) is currently in the research phase. Actually, AFS system adopt the front wheels’ angles base on the actual input steering angle from the driver according to vehicle handling dynamics performance. While, the AIFS controls the angle of each front wheel individually to avoid reaching the saturation limits of any of the front wheels’ adhesion. In this paper modeling and analysis of an AIFS is presented with Tire Work Load (TWL) based controller. Magic Formula tire model is implemented to represent the tire in lateral slip condition. A specially derived 3-DOF vehicle handling model longitudinal, lateral and yaw motion with four wheels is capable for studying AIFS implementing proposed control strategy. AIFS system is proposed to implement two main control strategies, which are PI controller only for yaw rate correction and the other controller incorporate a Fuzzy controller for TWL in addition to the prescribed PI controller. Simulation of the developed model with the proposed control strategies is been tested on constant radius maneuver at high vehicle lateral acceleration levels. Furthermore, the effect of split adhesion, on both track sides, is also investigated. The effect of PI feedback gains and the Fuzzy TWL controllers had been validated to eliminate the possibility of losing directional stability of the vehicle.