Autonomous emergency braking optimal coordination control strategy for commercial buses considering safety and comfort

The traditional dual-stage warning and dual-grade braking autonomous emergency braking (AEB) control strategy has sudden change in the expected braking deceleration during the switch of working state, which will easily lead to significant longitudinal jerk of the vehicle and affect ride comfort during emergency braking. To solve this problem, an AEB optimal control strategy considering coordination safety and comfort is proposed. First, an in improved Time-To-Collision pre-estimation model was designed, and the AEB state threshold time determination method was proposed by combining vehicle braking process and driver emergency braking characteristics. Second, an AEB hierarchical control strategy was designed, the upper layer designed an expected braking deceleration optimal decision controller based on particle swarm optimization linear quadratic regulator (PSO-LQR), and introduced a comfort time compensation coefficient to rectification the PSO-LQR controller. Moreover, an expected braking deceleration tracking controller based on feedforward and robust integral sliding mode feedback control was designed in the lower layer. Next, an AEB software architecture based on AUTOSAR was designed to enhance the standardization of control strategy software code generation. Finally, the Hardware-in-the-loop test and real vehicle experimental results indicate that the proposed AEB optimal coordination control strategy can meet the safety requirements of emergency collision avoidance functions, and effectively reduce the longitudinal jerk compared to the traditional AEB control strategy, it significantly improves the ride comfort of commercial buses during emergency braking processes.