Research On Integrated Control Of Differential Steering And Active Suspension For Distributed Drive Electric Vehicles

The transmission system structure of distributed drive electric vehicles is simple,and the driving torque of each driving wheel is independently controllable.By controlling the left and right wheels of the vehicle which generate different torques,the wheels deflect around their respective main pins to achieve differential steering.This article takes distributed drive differential steering electric vehicles as the research object.When the vehicle undergoes differential steering,the body will tilt outward under the action of centrifugal force,causing a reduction in the normal load of the inner wheels.When the roll angle is too large,not only will the differential steering fail,but the vehicle will also roll over,seriously affecting handling stability of the vehicle.Therefore,controlling the active inclination of the vehicle body through active suspension can not only ensure the effectiveness of differential steering,but also improve the handling stability of the vehicle.Therefore,this article conducts relevant research on the integrated control of differential steering and active suspension of distributed drive electric vehicles.The main work content and conclusions of the article are as follows:(1)Based on the Carsim model,vehicle parameters have been extracted and the vehicle model has been modified.Firstly,the vehicle parameters required for simulation were extracted based on the selected vehicle model in Carsim software,and a linear vehicle model which was two degree of freedom was established.The vehicle model in Carsim was compared with the linear vehicle model which was two degree of freedom for simulation to verify the correctness of parameter extraction.On this basis,the selection and verification of the hub motor were carried out,and a simulation model of the hub motor was established in Simulink software.The vehicle model in Carsim was further transformed into a simulation model of a distributed drive differential steering electric vehicle,which lay the foundation for subsequent control research.(2)The differential steering control of distributed drive electric vehicles has been studied.Firstly,the dynamic model of the front wheel differential steering vehicle dynamics which includes the front wheel differential steering system is established,and the sliding mode variable structure controller based on the reference model is designed.The simulation is carried out through J-turn and double lane shifting conditions.The results show that the yaw rate of the front wheel differential steering vehicle can track the yaw rate of the reference model well under the action of the sliding mode variable structure controller,illustrating that steering function of distributed drive electric vehicles can be achieved through the front wheel differential steering system,which can prepare for the research on integrated control of differential steering and active suspension.(3)A study has been conducted on the inclination control of distributed drive electric vehicle active suspension which uses traditional steering systems.Firstly,an active suspension inclination dynamics model and a reference model were established to obtain the reference inclination angle which were based on distributed drive electric vehicles using traditional steering systems.Based on the principle of model predictive control,an active body tilt controller was designed to achieve active body tilt during vehicle steering through the control force of the left and right active suspensions.The feasibility and superiority of active suspension tilt control were demonstrated through J-turn and double lane shifting conditions,laying the foundation for the integrated control of differential steering and active suspension.(4)The control strategy has been designed and the integrated control of differential steering and active suspension for distributed drive electric vehicles has been studied.Firstly,the theory of H_∞Robust control is introduced.Then,the H_∞robust controller is designed to achieve differential steering based on the vehicle dynamics model of differential steering and active suspension.Meantime,the active tilting of the vehicle body is achieved through active suspension.Then the simulation was conducted through J-turn and double lane changing conditions.The results showed that the controller can make the vehicle have the same yaw rate and body inclination angle as the reference model,which ensure the effectiveness of differential steering and improve the vehicle’s handling stability.