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

An apparatus for controlling an actuatable occupant restraint device having first and second actuatable stages, said apparatus comprising:

• a crash sensor for sensing crash acceleration and providing a crash acceleration signal indicative thereof;
• an average crash acceleration determiner responsive to said crash acceleration signal for determining an average crash acceleration value and providing a signal indicative thereof;
• and
• a controller operatively coupled to said first and second actuatable stages, said controller effecting actuation of said first actuatable stage upon said determined average acceleration value exceeding a first threshold value, and said controller determining a crash severity index having a value responsive to a time interval from when said determined average crash acceleration value exceeds said first threshold value to when said determined average crash acceleration value exceeds a second threshold value, said controller effecting actuation of said second actuatable stage in response to said determined 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 at a substantially central location of the vehicle and providing a first crash acceleration signal indicative thereof;
• determining a velocity value in response to said first crash acceleration signal;
• sensing crash acceleration at a forward location of said vehicle and providing a second crash acceleration signal indicative thereof;
• effecting actuation of a first of said actuatable stages in response to at least one said determined velocity value exceeding a first threshold value and said second acceleration signal exceeding a second threshold value;
• determining at least one of a first crash severity index having a value responsive to a time interval from when said determined velocity value exceeds said first threshold value to when said determined velocity value exceeds a third threshold value, and a second crash severity index having a value responsive to the time interval from when said crash acceleration value exceeded the second threshold value to when it exceeds a fourth threshold value;
• and
• effecting actuation of a second of said actuatable stages in response to at least one of said first and second crash severity indexes.