Abstract:

In view of that the emergency braking system is prone to making an inaccurate decision on braking timing when road conditions change， an emergency braking strategy is proposed based on enhanced safety model with dynamic decision?making on vehicle kinematics. Firstly， a dynamic decision?making safety model is established based on vehicles’ speed and acceleration under the subdivided working conditions of the acceleration and deceleration states of target vehicle， so as to enhance the adaptability of the control strategy to the dynamic driving speed of the vehicle in extreme working conditions. Then， the road adhesion coefficient is obtained by continuous identification using unscented Kalman filter （UKF） algorithm， the relationship between road conditions and vehicle deceleration capability is established through braking performance tests on both real vehicle and model under a series of road conditions， and the model?dependent extreme deceleration parameters are updated real time according to road conditions， which further enhances the safety of control strategy and its adaptability to dynamic road conditions. Finally， the control strategy is verified through both the test on the road with continuously varying adhesion coefficient and C?NCAP test， and the results show that the UKF algorithm can get accurate identification results and the automatic emergency braking strategy can make the accurate decision on braking timing on the road with varying adhesion coefficient.

Key words: automatic emergency braking, road with varying adhesion, dynamic decision, safety model