Multi-mode Steering Control Technology For Electric Vehicle With Multi-system Integrated Steering Wheel Module

Electric vehicles with all-wheel steering by wire based on the hub motor and the steering motor not only has the advantages of normal electric vehicles in environmental protection and energy saving,but also can better control the vehicle’s handling stability,active safety and other aspects.In addition,the wire-controlled all-wheel steering electric vehicle with fourwheel independent drive and independent steering also provides the possibility of multifunctional steering and enriches the driving function of the vehicle,which has a broad development potential.Based on the wire-controlled all-wheel steering electric vehicle that can realize multiple steering functions,this paper realizes the design of the multi-system integrated steering wheel module,proposes the multi-steering mode and dynamic stability control strategy based on the multi-system integrated steering wheel module,and builds the vehicle dynamics model.In addition,this paper analyzes the response changes of the whole vehicle when switching between different steering functions,and determines the safe initial state of the vehicle during the mode switching process.Then,a real-vehicle test platform is built based on the analysis of the research object,and the model strategy and multi-functional steering of the vehicle are verified.The specific research content includes:(1)Design an integrated steering wheel module with multiple steering modes,and an electric vehicle prototype based on a multi-system integrated steering wheel module.First,the expected performance indicators of the prototype vehicle are clarified,and the drive mode,steering mode and load distribution of the whole vehicle are designed according to the expected performance indicators,and the drive motor and drive power parameters are matched.Subsequently,a multi-system integrated steering wheel module that can achieve multiple steering functions is designed,and the multiple steering functions that can be achieved by the electric vehicle based on this module are analyzed to ensure the realization of the expected steering function.(2)The multi-steering mode control strategy and dynamic stability control strategy based on the multi-system integrated steering wheel module are proposed.First,a multi-steering mode control strategy is built based on Stateflow to ensure that the vehicle can switch between different modes.Then the model tracking-based dynamic stability control strategy realizes the reasonable allocation of the wheel angles of the vehicle in the four-wheel steering mode,ensuring that the front and rear wheel rotate out of phase at low speeds and the same phase at high speeds,which improves the steering stability of the vehicle in four-wheel steering mode.(3)The whole vehicle model is built based on the multi-system integrated steering wheel module.Build a complete vehicle model of a wire-controlled all-wheel steering electric vehicle including vehicle body dynamics model,wheel dynamics model,tire model,etc.Finally,the function of each subsystem module in the Simulink vehicle model is analyzed.(4)Vehicle control strategy verification and multi-mode switching simulation analysis.Firstly,the simulation platform is used to verify the vehicle dynamic stability control strategy based on model tracking in the four-wheel steering mode.Then the simulation analysis when the vehicle is switched from the two-wheel steering mode to a different mode is carried out.The response state of the vehicle when switching between different steering modes is studied,and the initial state of the vehicle when the mode is switched is determined from the perspective of vehicle stability and safety.(5)A real vehicle experimental platform for wire-controlled all-wheel steering electric vehicles is built.First,the upper-level control module of the test vehicle is designed,and then the vehicle communication CAN network is constructed.A real-vehicle test of the electric vehicle based on the multi-system integrated steering wheel module is conducted.The results show that the designed control strategy has a good control effect,and the electric vehicle prototype based on the multi-system integrated steering wheel module can effectively realize the expected multiple steering functions and meet the expected performance indicators.