Method and apparatus for controlling an actuatable safety device

1. A method for determining a crash condition of a vehicle comprising the steps of:

sensing crash acceleration in a first direction substantially parallel to a front-to-rear axis of the vehicle and providing a first acceleration signal indicative thereof;

sensing crash acceleration in a second direction substantially parallel to a side-to-side axis of the vehicle and near opposite sides of the vehicle and providing second acceleration signals indicative thereof;

determining a transverse crash value functionally related to the second acceleration signals;

comparing the determined transverse crash value against a safing threshold; and

determining a crash condition of the vehicle in response to (a) the comparison and (b) the first acceleration signal wherein said step of determining a transverse crash value functionally related to the second acceleration signals includes the step of determining a sum of moving averages of absolute values of acceleration in the second direction based on the second acceleration signals.

2. The method of claim 1 further comprising the step of providing an actuation signal for actuating an actuatable safety device of the vehicle in response to determining a crash condition of the vehicle.

3. The method of claim 1 wherein said step of determining a transverse crash value functionally related to the second acceleration signals includes the steps of:

determining moving averages of absolute values of acceleration in the second direction based on the second acceleration signals, and

determining the transverse crash value based on the determined moving averages of absolute values of acceleration in the second direction.

4. The method of claim 3 wherein said step of determining the transverse crash value based on the determined moving averages of absolute values of acceleration in the second direction includes the step of determining the transverse crash value based on the determined sum of the moving averages of absolute values of acceleration in the second direction.

5. The method of claim 1 further comprising the steps of:

determining crash velocity in said first direction from the first acceleration signal;

determining crash displacement in said first direction from the first acceleration signal; and

comparing the determined crash velocity as a function of the determined crash displacement against one of a discrimination threshold and a switched discrimination threshold; and

wherein said step of determining a crash condition of the vehicle comprises determining a crash condition of the vehicle in response to both the determined crash velocity as a function of crash displacement exceeding one of the discrimination threshold and the switched discrimination threshold and the transverse crash value exceeding the safing threshold.

6. An apparatus for determining a crash condition of a vehicle, said apparatus comprising:

a first accelerometer for sensing crash acceleration in a first direction substantially parallel to a front-to-rear axis of the vehicle and providing a first acceleration signal indicative thereof;

second accelerometers for sensing crash acceleration in a second direction substantially parallel to a side-to-side axis of the vehicle and near opposite sides of the vehicle and providing second acceleration signals indicative thereof; and

a controller determining a transverse crash value functionally related to the second acceleration signals and comparing the transverse crash value against a safing threshold, the controller also determining a crash condition of the vehicle in response to (a) the comparison and (b) the first acceleration signal wherein the controller determines the transverse crash value as a sum of moving averages of absolute values of acceleration in the second direction based on the second acceleration signals.

7. The apparatus of claim 6 wherein the controller also provides an actuation signal for actuating an actuatable safety device of the vehicle in response to determining a crash condition of the vehicle.

8. The apparatus of claim 6 wherein the controller determines the transverse crash value from moving averages of absolute values of acceleration in the second direction based on the second acceleration signals.

9. The apparatus of claim 6 wherein the controller further determines a crash velocity and a crash displacement from the first acceleration signal and compares the determined crash velocity as a function of the determined crash displacement against one of a discrimination threshold and a switched discrimination threshold, the controller determining a crash condition of the vehicle in response to both (a) the determined crash velocity as a function of the determined crash displacement exceeding one of the discrimination threshold and the switched discrimination threshold and (b) the transverse crash value exceeding the safing threshold.

10. The apparatus of claim 9 wherein at least one of the discrimination and transverse thresholds is a variable threshold.

11. The apparatus of claim 9 wherein at least one of the discrimination and transverse thresholds is a fixed threshold.

12. The apparatus of claim 6 wherein the first accelerometer is located at a substantially central vehicle location.