Integrated yaw and rollover stability control of an off-road vehicle with mechanical elastic wheel

Abstract

An integrated control algorithm of the differential braking and the active suspension to improve yaw and rollover stability of vehicles with mechanical elastic wheel (ME-Wheel) is developed. By simplifying the structure of ME-Wheel, a fitting tire model named brush model is constructed. Then, a nonlinear 8-DOF vehicle model with ME-Wheel is built up for rollover prevention, which utilizes a predictive load transfer ratio (PLTR) as the rollover index and a Kalman filter is used to eliminate the measurement noise. In order to design an integrated control algorithm, fuzzy proportional-integral-derivative (PID) methodology is adopted by simultaneous control of the yaw and roll motions. The proposed algorithm, based on the idea that makes yaw stability controller and roll stability controller work independently first, then unifies by way of weight according to fuzz control, after that, brake force distributor selects single efficient braking wheel to achieve yaw moment and one of the front braking wheels with varying brake pressure to achieve the desired brake torque and the wheel slip regulator is designed with sliding mode control technique to prevent the wheels from locking; and the active suspension system alters the stiffness of the active suspension to prevent rollover. Simulation results show that the integrated yaw and rollover stability control system could improve the handing stability of vehicle under the limit driving conditions, and prevent rollover happening.