Power-Rate Crash Sensing Method for Safety Device Actuation

The single-point electronic accelerometer has been developed to overcome the limitations and cost of current multiple mechanical sensor systems for crash detection and airbag deployment. An electronic sensor yields a signal which is capable of being processed digitally, thereby allowing more advanced algorithms for crash detection. Previous methods of detection have included velocity level detection and energy level detection. These methods exhibited serious limitations for certain types of crashes and potential inadvertent deployment problems. A new system, the Power-Rate method, has been developed to overcome the limitations of prior methods.

The Power-Rate method is based on the first derivative of power. It uses measures of acceleration, velocity, and jerk to determine whether the level of crash intensiity is potentially great enough to necessitate airbag deployment. The system has an inherent predictive capability, which yields earlier fire times for problem crash types. It also utilizes advanced smoothing techniques to overcome inadvertent deployment situations. The algorithm is based on a firm foundation in physics. It is implemented digitally, which gives greater system reliability and overcomes component variation due to temperature, aging, and manufacturing. The physical basis of the algorithm will be discussed, along with a flow diagram of the system which shows how the digital signal processing of the analog sensor output signal is accomplished.