Analysis Of Control Strategy Based On Four Wheels Steering And Four Wheels Independent Driving Vehicle

Problems such as energy shortages and environmental pollution are facilitatedwith the rapid addition of the car ownership all over the world. The vehicle based onthe hydrostatic transmission with secondary regulation technology can recycle thebraking energy and reuse it when the vehicle starts or accelerates. Then the energyutilization rate is improved and environmental pollution is reduced. It is incompliance with the energy-saving and emission-reduction policy. In addition, thedriver can carry out independent driving, braking and steering control with the fourwheels equipped independent hydraulic pump/motor and steering configuration. Thusit provides a basis for improving steering stability, increasing ground adhesionutilization and preventing slip.As for the steering stability problem, this article analyzes the working principleand steering configuration of the hydraulic vehicle. Then the relationship betweenfront wheels and rear wheels steering angle is analyzed based on the Ackermannsteering model and all these angles are calculated according to the zero sideslip anglecontrol strategy. According to the2DOF linear vehicle model, the sliding modevariable structure controller based on yaw rate is designed and the system stability isproved with the Lyapunov method. In order to verify the effectiveness of thecontroller, the controller simulation test is carried out with MATLAB/Simulink. Thesimulation results show that the vehicle steering stability can be controlledeffectively and the steering radius is reduced at low speed.As for the coordination control of four wheels, this article analyzes the wheelsforce coordination distribution and the strategy is designed. In order to verify theeffectiveness of the strategy, the control model is tested with MATLAB/Simulink.The simulation results show that the control strategy can make the wheels work incoordination in driving/braking situation and the ground adhesion force is used fully.The vehicle model in this article has no differential mechanism, thus the activedifferential control is very important. This article establishes a6DOF nonlineardynamics model and the yaw rate and sideslip angle are calculated to judge whetherthe vehicle is in stability state. Then the calculation based on the model is made tojudge whether the wheels have the slip. When the wheels have the slip phenomenon,the wheels need a P control and fuzzy control based on a neuron. At last thecontroller simulation test is carried out with MATLAB/Simulink. The simulationresults show that the control strategy can control the wheels slip well.