Supplemental inflatable restraint system having a rear impact algorithm for seat belt pretensioner
 A system having an accelerometer and a micro-controller responsive to acceleration signals for deploying an air bag as well as activating a pretensioner upon frontal impact includes an algorithm for activating the pretensioner upon rear impact. A frontal crash algorithm is executed when the acceleration exceeds a negative threshold and a rear impact algorithm is enabled when the acceleration exceeds a positive threshold. Rear impact severity is tested by integrating positive acceleration samples and issuing an activation command when the integrated value attains a severity threshold value. Noise immunity results from the positive threshold and from resetting the integrated value to zero whenever a negative acceleration sample intervenes in the severity test. 
Delco Electronics Corporation
B B B B
B60R B60R B60R B60R
inventional additional inventional inventional
Jon P. Jiyao
Kelley Liu