Method and apparatus for controlling an actuatable restraint device using crash severity indexing

An apparatus for controlling an actuatable occupant restraint device having a plurality of actuatable stages, said apparatus comprising:

• a crash sensor for sensing crash acceleration and providing a crash acceleration signal indicative thereof;
• a velocity determiner responsive to said crash acceleration signal for determining a velocity value and providing a velocity signal indicative thereof;
• first and second actuatable stages;
• and
• a controller operatively coupled to said first and second actuatable stages, said controller effecting actuation of said first actuatable stage upon said determined velocity value exceeding a first threshold value, and said controller determining a crash severity index having a value according to a time interval from when said determined velocity value exceeds said first threshold value to when said determined velocity value exceeds a second threshold value, said controller effecting actuation of said second actuatable stage in response to said crash severity index value.

A method for controlling actuation of an actuatable occupant restraint device having a plurality of stages, said method comprising the steps of:

• sensing crash acceleration and providing a crash acceleration signal indicative thereof;
• determining a velocity value in response to said crash acceleration signal;
• effecting actuation of a first of said actuatable stages upon said determined velocity value exceeding a first threshold value;
• determining, upon said velocity value exceeding a second threshold value, a crash severity index having a value according to a time interval from when said determined velocity value exceeds said first threshold value to when said determined velocity value exceeds said second threshold value;
• and
• effecting actuation of a second of said actuatable stages in response to said crash severity index value.