A Shock Mitigation of Pedestrian-Vehicle Impact Using Active Hood Lift System: Deploying Time Investigation

Abstract

This paper investigates the deploying time (or response time) of an active hood lift system (AHLS) of a passenger vehicle activated by gunpowder actuator. In this work, this is accomplished by changing principal design parameters of the latch part mechanism of the hood system. After briefly introducing the working principle of the AHLS operated by the gunpowder actuator, the governing equations of the AHLS are formulated for each different deploying motion. Subsequently, using the governing equations, the response time for deploying the hold lift system is determined by changing several geometric distances such as the distance from the rotational center of the pop-up guide to the point of the latch in the axial and vertical directions. Then, a comparison is made of the total response time to completely deploy the hood lift system with the existing conventional AHLS and proposed AHLS. In addition, the workable driving speed of the proposed AHLS is compared with the conventional one by changing the powder volume of the actuator.

Shock mitigation of pedestrians from sports utility vehicles impact using active pop-up and extended hood mechanisms: experimental work

“…The working principle of those systems can be understood from Figure 3 and 4. 31,32 Considering the operation procedures of the hinge module firstly. Figure 3(a) show the initial final state of the hinge module.…”

“…Figure 4 shows the working principle of the pop-up hood mechanism at the latch part that is redesigned based on the mechanism inside. 32 In order to transmit the force of the pyrotechnic actuators to lift the hood quickly, both the bracket release and the pop-up guide can be structurally designed and used. Then, those are rotated by the exploded actuator to lift the hood in the operation procedure.…”

“…Recently, the authors of this work introduced a new type of pop-up hood mechanism for passenger cars that lifts the hood by three pyrotechnic actuators which are installed at two hinge modules and one front latch modules. 31,32 It has been experimentally verified that the mechanical deployment time of actuating systems in hinge and latch modules are under 10 ms, respectively. Therefore, the total deployment completion time is less than 30 ms when the sensing and the signal processing time of 15 ms of the electronic control unit (ECU) is included.…”

“…It is noted that the pop-up hood lift mechanism has been implemented and tested in the authors' previous works focusing on the deployment time. 31,32 The second is to propose a new extended hood mechanism to protect a pedestrian who collides with the front area of the windshield on a SUV. In order to demonstrate the effectiveness of the two different proposed hood mechanisms, the headform impact testsassociated with the appropriate sensors, such as accelerometer, have been undertaken.…”

An experimental comparison of the pedestrian safety performances of a spring actuator and a pyrotechnic actuator for deploying an active hood lift system

“…This includes the cicumstance when the kinetic energy of the hood is directly applied to the pedestrian. 10 Furthermore, it is noted that there is a sharp increase in the number of fatal accidents when the impact driving speed increases. 11,12 In this respect, a reduction in the deployment time of the system can protect more pedestrians from fatal accidents.…”