Research On Composite Brake Control Strategy Based On Road Type Identification

Faced with energy and environmental challenges,electric vehicles have developed rapidly in recent years due to their advantages in energy saving and emission reduction,but the driving range of electric vehicles still can’t meet people ’s expectations and needs.Regenerative braking technology is the key technology to improve the driving range of electric vehicles.After the brake anti-lock braking system ABS is triggered,how to coordinate the regenerative braking with the ABS is not only related to brake safety,but also affects the braking energy recovery rate.Regarding the problem that the current regenerative braking and ABS coordinated control strategy cannot adjust the anti-lock braking control parameters and the regenerative braking adjustment rate according to different road types,the following aspects are studied:(1)Based on the vehicle braking dynamics biaxial model and Burckhardt tire model,the relationship between the braking longitudinal force and the slip rate is established,and the mathematical model of the transfer function from braking torque to wheel slip rate is further derived.From the angle of system stability.The relationship between the braking stability of front and rear axle and the peak slip rate of road is analyzed from the perspective of the braking system stability.(2)Based on the steady-state relationship between the stability of the front and rear axle braking systems and the road slip rate,a coordinated control strategy of regenerative braking and ABS anti-lock is proposed based on road type identification.Based on the traditional double threshold value,different antilock control parameters are designed to switch according to the stability of the braking system,and the adaptive adjustment of the regenerative braking exit rate is performed according to different road types.(3)The mathematical model of pure electric vehicle braking system is built in Matlab / Simulink,which mainly includes braking dynamics model,battery model,motor model,braking system model,tire model,road surface type recognition model and controller model to coordinate anti-lock control strategy.(4)The correctness and real-time performance of the coordinated control of regenerative braking and ABS anti-lock based on road recognition are simulated,analyzed and verified,and the influence mechanism of different anti-lock control parameters and different regenerative braking exit rates on braking distance and braking energy recovery rate under the same initial braking speed is explored.