Vehicle steering assistance in extreme situations using a fuzzy logic controller

An innovative approach to vehicle control is presented which utilizes a relatively new control technique based upon fuzzy set theory. Within this paper, a Fuzzy Logic Controller (FLC) is developed which when combined with front and rear independent steering (FRIS) provides the driver greater control of his vehicle by minimizing undesirable spin caused by icy road conditions.

This study first develops a nonlinear mathematical model of a rubber tired vehicle which employs FRIS. The model is simulated using road-tire slip disturbances which mimic icy road conditions in order to observe the vehicle's dynamic characteristics. A FLC is then developed which monitors the vehicle's yaw rate error (spin) and road-tire slip ratios. Based on these two inputs, the FLC computes both a front and rear steering compensation angle. These compensation angles are summed with the driver's requested steering angle and fed to the vehicles steering mechanism.

With the FLC integrated into the mathematical vehicle model, simulations are again performed. Simulation results show that vehicle spin is considerably reduced with the FLC as compared to the uncompensated vehicle. The results further support the use of FRIS to enhance driver's safety while also re-enforcing FLC methods as an effective control technique.