The Stability Control Method Of Four-wheel Independent Drive Electric Vehicle On Different Adhesive Conditions

Four-wheel independent drive vehicle is an advanced vehicle, which four wheels arecontrolled and driven independently. Compared with the traditional vehicle, it has a moreand flexible mode of drive. Each wheel is available work at the best interval of slip rate,and provides the best driving force for vehicle.This thesis takes4WID-EV as the main research object, and designs the uppercontroller and lower actuator with hierarchical control strategy. The upper controllerlaunches a joint control for the vehicle’s lateral stability and longitudinal dynamic, anddetermines the related control methods in combination with feed forward control,feedback control and optimal control theory. The lower actuator optimizes and distributesdriving force of the driving wheel, and ensures that the vehicle’s dynamic performance andstability.Firstly, this paper introduces the hardware and the main structure parameters of thesystem, establishes the combined simulation model. Expounds the operation mechanismof the mechanical dynamics simulation software ADAMS, and then analyzes theinvocation process of the established vehicle module, tire and road module. Put forwardthe combined control strategy and the control process of the vehicle.Secondly, using the vehicle’s mathematical model derived from the Newton’s method,establishes the mathematical model for reference, based on the analysis of frequencycharacteristics and step characteristics. With the ideal yaw angular velocity for trackingobjects, establishes the feed-forward controller. To make up for its lack of side-slip anglecontrol, then set up the feedback controller using the linear quadratic optimal control,andmeet the requirements of the vehicle lateral stability.Finally, realizing the recognition of wheel slip rate based on the optimal controltheory. Using sliding mode variable structure control designs the torque controller for thedriving wheel. In the lower actuator section, to achieve the upper controller of vehiclelateral stability and longitudinal dynamic control purpose, using the mathematicalprogramming method establishes the objective function and achieves the reasonabledistribution on the driving moment. Under different adhesive conditions, the controller is applied to the combination simulation of ADAMS and MATLAB, and to verify theprecision of the simulation model and the controller of the stability and rapidity.