Supplemental restraint deployment method providing rough road immunity

A deployment method for vehicular supplemental restraint system having an acceleration sensor and a restraint device to be deployed for occupant protection in a crash event, the method comprising the steps of:

• monitoring an output signal of the acceleration sensor to generate an indication of a potential crash event initiation;
• resetting the indication of crash event initiation if the output signal falls below a reset threshold for at least a predetermined period of time;
• processing the acceleration sensor output signal to obtain a measure of crash severity, beginning each time said indication of potential crash event initiation is generated;
• normally deploying the restraint device if the measure of crash severity exceeds a primary deployment threshold indicative of a severe crash event;
• generating an indication of a rough road condition for a timed period if (a) the measure of crash severity exceeds a rough road threshold and (b) the indication of crash event initiation is subsequently reset with no intervening deployment of the restraint device;
• inhibiting the normal deploying of the restraint device during said timed period if the measure of crash severity is less than a secondary deployment threshold which is initially higher than said primary deployment threshold;
• and
• deploying said restraint device during said timed period if the measure of crash severity exceeds said secondary deployment threshold.

A deployment method for vehicular supplemental restraint system having an acceleration sensor and a restraint device to be deployed for occupant protection in a crash event, the method comprising the steps of:

• monitoring an output signal of the acceleration sensor to generate an indication of a potential crash event initiation;
• resetting the indication of crash event initiation if the output signal falls below a reset threshold for at least a predetermined period of time;
• processing the acceleration sensor output signal to obtain a measure of crash severity, beginning each time said indication of potential crash event initiation is generated;
• normally deploying the restraint device if the measure of crash severity exceeds a primary deployment threshold indicative of a severe crash event;
• initializing a counter to indicate a rough road condition if (a) the measure of crash severity exceeds a rough road threshold and (b) the indication of crash event initiation is subsequently reset with no intervening deployment of the restraint device;
• periodically indexing said counter so long as another indication of a potential crash event is not generated;
• resetting said counter when a count stored in the counter reaches a predefined value;
• and
• inhibiting the normal deploying of the restraint device between the initializing and resetting of said counter if the measure of crash severity is less than a secondary deployment threshold which is initially higher than said primary deployment threshold;
• and
• deploying said restraint device between the initializing and resetting of said counter if the measure of crash severity exceeds said secondary deployment threshold.