Research On Driving Stability Control Strategy Of Distributed Drive Electric Vehicles

As a new type of drive for electric vehicles,the distributed drive has various advantages such as simple structure and easy control,and is one of the important development directions of new energy vehicles in the future.In the last decade,research has matured in the field of active safety control for distributed drive electric vehicles.Distributed drive electric vehicles,as strongly coupled non-linear dynamos,are constrained by kinematic coupling in straight-line and steered driving stability control,and a single control objective does not guarantee the best response to the remaining stability objectives.To address the problem of motion coupling in the stability control of distributed drive electric vehicles,this thesis proposes a motion decoupling control strategy to improve the linear and steering driving stability of distributed drive electric vehicles based on the characteristics of individually controllable drive wheels of distributed drive electric vehicles,realising the motion decoupling of such vehicles and improving their driving stability.The main research elements of this thesis are as follows.(1)The vehicle dynamics parameters were identified through real-world tests,the Carsim vehicle system was customised based on the identified dynamics parameters,a Carsim model of the vehicle was established,the maximum speed of the vehicle,the maximum gradient of the vehicle climbing and the acceleration time of the vehicle to 100 were used to design the power system and establish the Simulink model of the wheel motor,and finally,the effectiveness of the joint Simulink/Carsim simulation of the vehicle was verified based on vehicle stability experiments.(2)Through the analysis of the current situation of the research on the driving stability of distributed drive electric vehicles,this paper divides the research direction into the research on the stability of the straight-line driving of distributed drive electric vehicles and the research on the stability of the steering driving of distributed drive electric vehicles,and analyses the motion coupling existing between the straight-line driving and steering driving of distributed drive electric vehicles respectively,and designs special controllers for decoupling control.(3)The decoupled optimal control strategy based on drive torque is proposed for the driving stability problems such as vehicle runout and motion coupling that exist during the straight-line driving of distributed drive electric vehicles.The upper control layer is responsible for the control of traverse motion and drive anti-skid control;the middle control layer performs secondary planning of the additional torque from the upper control layer,based on which the decoupled control of traverse motion with wheel anti-skid is realised;the lower control logic layer is responsible for the optimal distribution of drive torque for speed following control.(4)A distributed drive electric vehicle steering and driving control strategy based on a robust decoupling control algorithm is proposed for the lateral control of vehicle steering conditions that do not take into account the lateral pitch motion and cause speed reduction and excessive wheel slip in the stability control process.This paper proposes a multi-objective constrained optimization method based on robust decoupling control to achieve vehicle traverse pitch stability and enhance the spatial stability of the vehicle steering while avoiding vehicle speed reduction and tyres entering the nonlinear region during the control process.