Study Of The Control System Of Active Head Restraint Based On Moving Window Specific Power Algorithm

Not only the incidence of rear-end collision of the vehicle is very high but also the disability rate as much as 53.5%. While the whiplash injury caused by collision brings great pain to the patients, it als o causes enormous economic losses to the society. In order to reinforce the occupant protections in the rear-end collision, the tests standard of whiplash test of 2015 C-NCAP is more strict than the 2012 version. However, at present only the luxury vehicle s can afford the active head restraint which not only can secure the safety but also can take into account the side view, while in the common cars it is very rare. In order to make the active headrest popularized in the ordinary car, this paper designed an d developed a simple, reliable, low cost, repeatable collision response active safety head.In this paper, headrest mechanical system, with electromagnetic iron lock and trigger, is working in spring driven way and a light-touched switch is adopted to check whether the occupant’s head is on the headrest. When the occupant’s head leans on the headrest, the light-touched switch will be closed, and control system will find the I/O interface that connected to the light-touched switch located at low voltage level through detection, confirming that occupant’s head has already been effectively supported on headrest. So even in the case of rear collision, headrest will not bounce off. By comparing the existing algorithm based on acceleration detection on collision accident, the moving window specific power algorithm is proposed and verified, and meanwhile, threshold and window width of the algorithm are confirmed so that this control algorithm of headrest has the feature of quick response and strong anti-interference. In order to verify the protection effect of the th e active headrest pop-up displacement to the occupant, the driver seat of the Taurus and Bio RID Ⅱdummy model were used in this paper to simulate the C-NCAP whiplash test. The posture of the dummy model and the position of the headrest were set to the locat ion of the pass line identified by the international whiplash protection group, where the simulation of the expansion and unexpansion of the headrest were conducted. The results show that the NIC reduced by 55.79% when the headrest is expanded. According to the whiplash test standard of 2015 C-NCAP,the test score increased by 112.59% compared to the unexpanded headrest. Headrest hardware of control system is built with 16-bit Freescale MC9S12G48 chip as the core and all components are on the level of car gauge. In terms of hardware system and the moving window specific power algorithm, headrest control system is designed based on a set of modular C language software program code.To verify the effectiveness of the head restraint mechanical system and control system, this paper carried out several tests on it including the mechanical system unfolding test, impact force testing experiment, preventing false triggering test, control accuracy test and sled rear impact test. The results show that the mechanical system of the active head restraint can be fully expanded within 24 ms. The forward movement of the active head restraint is 41 mm, and the upward movement is 44 mm. The maximum impact force of the headrest is 100.36 N, which can effectively prevent false triggering, the error of the control system is less than 1ms, in the sled rear impact test at the speed of 15.65km/h, the control system could send out the controlling signal within 15 ms, and the whole system of the headrest can fully expand in 49 ms from the collision starting time.