Research Of Active Front Wheel Steering Control Methods For 4WD Electric Vehicle

Energy-saving, environmental protection and safety are the theme of modern automobile development. Facing the challenges of energy and environmental in 21st century, the world take automobile saving energy and environmental protection as the important research field. The electric automobile is received more attention among them. At the same time, automobile security influence transportation road safety, while stability of automobile is one of effective actions for enhancing secure effective.As four-wheel independent driving electric vehicle based on wheel motor to research object, based on the analysis of vehicle stability on large turn, the technology of vehicle stability control is studied by way of front wheel active steering。On the basis of theories of the guaranteed cost control and the PID control, the corresponding control algorithms are determined, and the methods are also studied. This provides a thought to improve vehicle manipulate stability.First the requisite model is established, including dynamics model of vehicle, motor model and confederate simulation model. Overlooked some parts, simplified vehicle dynamics model is established in ADAMS/View, motor model and control model are established in Matlab/Simulink, finally the confederate simulation model is completed.Second active front wheel control methods are studied. Based on two freedom degrees of vehicle model, control strategy which takes yaw angle rate and centroid sideslip angle as tracking object, and front wheel corner and direct yaw moment as control input is put forward. Considering of uncertainty of tires and direct yaw moment, feedforward-feedback controller is designed. Four wheel drive force are allocated by using feedforward compensation and yaw moment which is formed for driving force difference value. It makes yaw angle rate and centroid sideslip well of tracking the desirable model when the vehicle drive in a turn. Finally, the controller is used in confederate simulation, vehicle stability is studied on conditions of step input and sine input, the accuracy of the simulation model and the stability and quickness of controller are verified.