Research On Steering Handling Stability Control Strategy Of Four In-wheel Motor Driving Vehicle

The difference between the in-wheel motor driving vehicle and the traditional vehicle is mainly in the power and transmission system.The motor placed on the wheel hub drives the wheel directly,leading to a common system consisting of motors,wheels,brake systems and transmissions,which gets rid of a series of complicated mechanical drive devices,makes further extension of interior space,reduces the weight of the vehicle and is more conducive to vehicle dynamics control.This thesis is trying to conduct research on control strategy for enhancing the handling stability of the in-wheel motor driving electric vehicle.I mainly engage in the several work as follows:(1)The vehicle dynamics model and a vehicle reference model with two degrees of freedom based on simulation of CarSim/MATLAB/Simulink were established.Furthermore,the efficiency of the vehicle model is verified in terms of vehicle straightline and steering capability.(2)Focusing on the relationship between yaw rate,centroid sideslip angle and vehicle stability,we analyzed the not only the different states when the in-wheel motor driving vehicle was unstable,but also the root causes of instability.According to the target of the redundancy control system,a vehicle control system based on hierarchical structure was designed to improve vehicle handling performance and stability,in which the upper controller calculates the generalized moment by controlling the motion state of the vehicle,while the lower controller distributes the torque to the four wheels.(3)In order to model for the upper controller,the velocity tracking model based on PID control and the yaw moment model based on fuzzy logic were established.In addition,the upper controller was simulated under the open loop test.(4)The lower controller was established based on rule and optimal algorithm.And the control strategy is verified under the closed loop test.Besides,the two distribution methods were compared.(5)The real vehicle test platform was built and the reliability of handling stability strategy was verified in the test platform.