An autonomous emergency braking strategy based on non-linear model predictive deceleration control

Surrogate safety measures (SSM) are used to assess the risk for autonomous emergency braking system (AEBS). Developing appropriate SSM and accurately executing the braking request are the key issues. Time-to-collision (TTC) is a typical time-based SSM with limitations. By analyzing the braking process, this paper proposes a new SSM based on deceleration rate to avoid collision (DRAC). As the brake actuator, vehicle electronic stability control (ESC) system has many problems, such as large overshoot and pressure fluctuation. Considering the model of hydraulic control unit (HCU) and vehicle, a deceleration controller based on non-linear model predictive control (NMPC) is proposed. Based on this, a layered AEBS architecture is proposed. The upper-layer AEBS controller calculates the expected deceleration based on modified DRAC (MDRAC), and transmits it to the lower-layer NMPC deceleration controller. Finally, the simulation and experimental tests are carried out. The results show that the system has a fast and stable response. In addition, the performance of the proposed AEBS strategy is tested according to the Euro-NCAP test protocol. Comparing the results with the TTC method, the proposed method can improve the stability of the distance margin by more than 0.55 m, which ensures the safety and improves the stability of the vehicle.

Automated summary

This paper proposes a new surrogate safety measure (SSM) based on deceleration rate to avoid collision (DRAC) for the assessment of autonomous emergency braking system (AEBS). A layered AEBS architecture is proposed, with an upper-layer controller calculating the expected deceleration based on modified DRAC (MDRAC) and transmitting it to a lower-layer nonlinear model predictive control (NMPC) deceleration controller. Simulation and experimental tests demonstrate that the system has a fast and stable response. The proposed AEBS strategy improves the stability of the distance margin and ensures the safety and stability of the vehicle compared to the time-to-collision (TTC) method.