Fuzzy logic control method for deployment of inflatable restraints

A control method for controlling deployment of individual stages of a vehicle inflatable restraint based on a plurality of measures of longitudinal vehicle acceleration during a crash event and an elapsed time of the crash event, the method comprising the steps of:

• computing a change in velocity corresponding to the measured longitudinal acceleration in frontal and central portions of the vehicle;
• predicting an occupant displacement due to the measured longitudinal acceleration in the central portion of the vehicle;
• comparing the predicted occupant displacement to a displacement threshold;
• if the predicted occupant displacement exceeds said displacement threshold, then determining a severity of the crash event by applying fuzzy logic membership functions and predetermined fuzzy logic rules to the elapsed rime and the computed change in velocity;
• comparing the determined crash severity with a first crash severity threshold associated with a first stage of the restraint;
• resetting the elapsed time of the crash event if the elapsed time is greater than a reference time;
• repeating the step of determining the severity of the crash event if the comparison reveals that the determined crash severity is less than the first crash severity threshold and the elapsed time is less than said reference time;
• and
• initiating deployment of the first state of the restraint if the comparison reveals that the determined crash severity exceeds the first crash severity threshold.