Research On Coordinated Control Of Four-wheel Independent Drive And Steering Electric Vehicle Considering Driver Characteristics

Faced with increasingly serious environmental and energy problems,the country’s vigorous promotion of electric vehicles made electric vehicles have already entered thousands of households.At the same time,the market requirements for handling stability,driving comfort,active safety,intelligence and various kinds of properties are gradually increasing.In addition.With the continuous development of automobile intelligence,the individual requirements for automobile design become increasingly prominent.Four-wheel independent drive and steering electric vehicles have unique advantages,easy to consider driver characteristic and provide a good platform for realizing vehicle control considering driver characteristics because of its four-wheel driving torque and angle independently controllable and it respond quickly and control precisely.This paper based on the four-wheel independent drive and steering electric vehicle,carries out coordinated control of the entire vehicle considering the characteristics of the driver.The main contents include:(1)Establish a four-wheel independent drive and steering electric vehicle simulation modelA four-wheel independent drive and steering electric vehicle model is built by CarSim and MATLAB/Simulink software.Set the parameters of the transmission,suspension,tires and other subsystems in CarSim,build steering motor and drive motor model in Simulink.The two jointly establish a complete vehicle model for the study of the coordinated control strategy in this paper.(2)Research on the classification and identification of driver characteristicsBased on the driving simulator platform,the driver’s corresponding manipulation data is collected under the designed test conditions.The fuzzy C-means clustering algorithm is applied to classify the processed driver characteristic value data,and the driver characteristics are classified into three types: cautious,general and aggressive.The BP neural network is used to establish the identification model of the driver’s acceleration and steering characteristics,and the online calculation program converts it into a driver’s characteristic identification module that can be embedded in the model.(3)Research on coordinated control of additional yaw moment and active steeringDesign a hierarchical coordinated control strategy for four-wheel drive and active four-wheel steering that considers the driver characteristics.At the input signal layer,a linear two-degree-of-freedom model and a reference model of driver steering characteristics are designed which can solve the parameters of the ideal yaw rate and the centroid side slip angle of the vehicle according to the current state of the vehicle and driver’s input.At the decision-making control layer,a two-input two-output coordinated controller applying fuzzy theory is designed.Adjusting the parameters of the fuzzy controller,the combined action of the additional yaw moment control and active steering enables the vehicle’s centroid slip angle and yaw rate to follow the ideal model.At the distribution execution layer,designs different feedforward four-wheel steering strategies according to the vehicle speed,and the steering angle value combined with the feedback of the coordinated controller output: the additional rear wheel angle work together to obtain the final result.The torque distributor receives the required torque considering the driver’s acceleration characteristics and the additional yaw torque,and then applies the quadratic programming algorithm to optimize the distribution of the four-wheel torque based on the tire load rate.(4)Experimental verificationBased on the simulation platform and hardware-in-the-loop driving simulator platform,the control strategy designed in this paper is tested and verified.The results show that the strategy proposed in this paper can identify the driver characteristics and achieve vehicle response that meets driver expectations,and complete the command execution of the four-wheel angle and driving torque,which proves the effectiveness and feasibility of the control strategy.