Research on Influencing Factors of Pressure Signal in Active Bonnet System for Passenger Vehicles

In pedestrian-vehicle collisions, head injuries constitute the primary cause of severe harm, predominantly resulting from the pedestrian's head striking hard points within the lower engine compartment. Due to their proven effectiveness in mitigating such injuries, active bonnet systems have gained widespread adoption. These systems typically utilize pressure tube sensors (a contact-based sensing method) to determine triggering based on pressure signal characteristics. However, this approach carries a risk of false activation. To investigate the factors influencing pressure signals in active bonnet systems, reduce false activation rates, and enhance pedestrian impact recognition, this paper uses peak pressure values and the 15-millisecond impulse integrals as pressure signal characteristics to analyze the effects of impact type, impact location, impact speed, and ambient temperature on pressure signals. All tested parameters demonstrably affect pressure signal characteristics. The peak pressure and integral impulse of the stone impactors are closely related to velocity and energy peak, and the remaining impactors did not show similar patterns. Compared to peak pressure values, the 15-millisecond impulse integral proves more effective as a trigger threshold index, offering superior discrimination between signals requiring activation and false activation signals. This research provides valuable references for defining test matrices and improving active bonnet system performance.