On Steering Control of Commercial Three-Axle Vehicle

The steering control laws of commercial three-axle vehicle are studied based on the closed-loop control model of the driver-vehicle-road. The steering characteristics of the three-axle vehicle can be improved through adding the steering of rear wheels. For a series of combined roads defined as standard roads where the vehicle is tested, a new proposal to optimize the design parameters of the steering system is presented. The cornering stiffness of front, middle and rear wheels and outer disturbance are considered as uncertain parameters varying over a limited range. A new controller of model-following variable structure is constructed and used for controlling front and rear wheels steering of the actual vehicle, so that the steering characteristics of the uncertain vehicle model and nonlinear vehicle model can follow the characteristics of the reference model (nominal model), namely, the vehicle can keep the same steering characteristics as the nominal model on the different roads. Simulation results have demonstrated that the proposed method is reasonable and practicable.