Abstract: In order to enhance the active safety of the vehicle, the control strategy for the vehicle automatic emergency braking system is studied. The control strategy is modeled with the idea of hierarchical control. The upper controller is a time-to-collision model for determining vehicle braking deceleration, which analyze the braking deceleration of brake system based on the drivers' emergency braking data of the vehicle rear-end accident depth investigation to determine the time-to-collision threshold with consideration of comfort. The lower controller analyzes the relationship between the tire model and the brake system according to the braking deceleration output from upper controller, and controls the vehicle by adjusting the braking pressure through PID control. The reliability of control strategy is verified under the standard condition of safety evaluation specifications and the effectiveness of the control strategy is validated through the reconstruction of rear-end accident scene. The results of simulation show that the control strategy devised can effectively avoid collisions with a relative speed lower than 65 km/h and can reduce the collision speed to the maximum extent with a relative speed higher than 65 km/h, reducing the severity of damage

Key words: active safety, automatic emergency braking, time-to-collision, hierarchical control