# Design and Performance Research of a Wearable Airbag for the Human Body
###### Abstract  
In this paper, an integrated wearable airbag is proposed to protect the vulnerable pedestrian during a vehicle-pedestrian collision accident. To evaluate the protection performance of this newly proposed integrated wearable airbag, the airbag inflator finite element model is first verified via an inflator tank test, and the simulated results agree very well with the test. Next, the finite element model of the vehicle-pedestrian model is established, including a simplified vehicle model and a biomechanical HBM with the integrated wearable airbag. The numerical results show the newly proposed wearable airbag can effectively protect the pedestrian by significantly reducing injuries to the head and chest. Since head injury is the most important injury type, a complete set of injury indexes is adopted to evaluate severity of head injury, including HIC\({}_{15}\), 3 ms resultant acceleration, and intracranial pressure. To further improve the protection performance of the airbag on the HBM's head, a parametric study is conducted towards two design parameters of the wearable airbag: inflator gas mass and pulling strap length. The parametric investigation shows 26 g gas and a 20 mm pulling strap can provide the best protection for the HBM's head. wearable airbag; pedestrian protection; pedestrian vehicle collision; finite element Article Design and Performance Research of a Wearable Airbag for the Human Body [PERSON], [PERSON] and [PERSON]  
[PERSON], [PERSON], [PERSON], W.  
head and hips when a person falls by an automatically inflated airbag. The inflated airbag can effectively absorb the impact energy of the fall and reduce the damage to the human body [4]. Meanwhile, airbag products for wearing have been put into the market. Wolk has developed a hip airbag [7]. The central computer of the airbag analyzes the direction and acceleration data, and automatically detects whether there is a fall. When a person falls, the inflator inflates carbon dioxide into the left or right airbag. The Wolk airbag has undergone extensive safety tests, and the inflation time is within 100 ms. In the Chinese market, there is a new product, the S-airbag, which can protect the head, back, and hips of the human body and prevent false triggering by recognizing 12 postures such as bending and sitting through AI chips with high computational power. Wearable airbags have also been utilized to protect bicycle and motorcycle riders. Unlike hip injuries due to falls, head and chest injuries occur most frequently and cause the highest fatality rates during the accidents [8; 9; 10]. The Italian brand Dainese has incorporated the concept of airbags into specific garments worn by motorcycle riders and designed a new product, D-AIR, which is capable of significantly reducing the impact forces on the rider in an accident event [11]. [PERSON] et al. [12] proposed an inflatable airbag helmet for bicycle riders. This inflatable airbag helmet can provide better protection than the traditional EPS helmet and can effectively reduce the risk of head and brain injury. [PERSON] et al. [13; 14] utilized three acceleration axes and three angular velocity axis sensors to obtain real-time bicyclist motion state, which is used to distinguish whether an accident occurred. In the numerical research of airbags, [PERSON] et al. [15] established the finite element model of an airbag, verified the airbag model through a chest impact test, and analyzed the impact of inflation pressure and airbag thickness on airbag performance. [PERSON] [16] established the finite element model of a wearable airbag, and connected it to the dummy. Thorax and shoulder impact tests were carried out, respectively, and the best inflation pressure was found. Regarding wearable airbag protection for the human body, currently there is a lack of effective wearable airbag devices for pedestrians in a vehicle-pedestrian accident. In this paper, an integrated wearable airbag is proposed to protect pedestrians, who are vulnerable during an accident.