Research On Starting Control Of Car Ramp Based On Pneumatic EPB

Hill-start as the typical driving condition of the car is complex for driver.Hill-start assistant system can avoid accidents caused by driver's faults and extend vehicle life.Electrical Parking Brake(EPB)integrates the temporary braking and the long-term parking function,and the parking brake is controlled by electronic control to improve the driving maneuverability.Focus on the problem of hill-start,a control strategy based on pneumatic EPB was proposed.This paper analyzed the change of the force in the process of hill-start and the principle of the pneumatic EPB,and presented the difficulties of hill-start control and ideal hill-start.The structure and mechanical properties of the composite brake chamber were studied,and the hill-start control target was proposed.The hill-start control flowchart was designed.The friction work and the impact degree were taken as the evaluation indexes of the hill-start quality.Focused on the hill-start control strategy of EPB,the friction work was decomposed and redefined.Aiming at the identification of slope resistance,the slope angle and the vehicle quality were studied separately.The factors influencing accuracy of the angle sensor were analyzed,and the algorithms of dynamic and static angle correction and filtering were proposed.The vehicle weight identification algorithm based on the longitudinal dynamic formula was designed and verified by vehicle test.The working characteristic of the solenoid valve was researched,and the PWM-PFM control mode was proposed.The relationship between the driving torque and the braking force in the process of hill-start was studied.The demand air pressure as ideal control target was proposed,and the Bang-Bang control algorithm and logic threshold control algorithm were analyzed and compared.The modeling and simulation analysis of hill-start control strategy were carried out to verify the feasibility of hill-start control strategy.The test data show that logic threshold control is more suitable than Bang-Bang control for the hill-start control proposed in this paper.The hill-start control strategy is verified to improve the friction work and the impact degree effectively.