Miller, 1 INJURY OPTIMIZATION OF THE FRONTAL CRASH SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPLOYMENT MATRIX

With the introduction of the FMVSS 208 upgrade for U.S. frontal crash safety, many new requirements were added. In order to meet these new requirements, manufacturers had to develop new methodologies for sensing, controlling, and deploying airbags. The standard achievement method is to use dual stage airbags with two firing thresholds. The objective of this research was to improve three key areas of the standard method: 1) Prevent risk of inadvertent high output deployment for small occupants. 2) Improve occupant injury by achieving the ideal deployment mode 3) Reduce the complexity of the system to increase robustness. In order to achieve these goals, it was proposed that a single ideal deployment mode could be developed by performing a parametric study where Time to Fire (TTF) and the delay between firing the first and second stage were varied independently for the driver and passenger Anthropomorphic Test Devices (ATDs). This was done for AM50% and AF5% ATDs in a front 40 km/h unbelted test mode. Once the ‘ideal’ TTF/delay was determined, the test speed was increased to 48 km/h and 56 km/h respectively for both belted and unbelted occupants. The research showed that for the driver, an early TTF (10-15 ms) with a 20-30 ms delay provided the best combination of restraint for the AM50% ATD. This also allowed for good injury results in the AF5% low risk deployment mode. For the passenger, an early TTF (10-15 ms), with a longer delay (130 ms) showed the best combination of injury results. This allowed for successful Out of Position (OOP) deployments as well as good frontal crash results. It was also discovered during this research that there are some key interior lay out items that must be maintained in order to use this type of deployment strategy. INTRODUCTION Prior to the FMVSS 208 upgrade, most vehicles used a single stage inflator with a simple on/off firing threshold. Figure 1: Pre FMVSS208 upgrade firing strategy In this case the airbag would be guaranteed not to fire below 13 km/h, and guaranteed to fire above 19 km/h. A gray zone is created between these speeds were either condition may occur, which is shown in Figure 1. This airbag firing strategy was designed to protect for the regulation matrix shown Figure 2. Figure 2: Pre FMVSS208 upgrade regulation matrix In an effort to increase protection for children and smaller stature adults, the U.S. government upgraded FMVSS208 to include Low Risk Deployments (LRD) for AF5% drivers and the OOP deployments for CRABI, C3Y, and C6Y children. Increased frontal crash regulations were also added to the FMVSS 208 upgrade [1-FMVSS]. The updated frontal crash regulation matrix is shown in Figure 3. 19 0 km/h 48 56 64 13