Patent ID: 7406376

Claim:
A determination device for a passive safety device that operates according to severity of a collision in a vehicle accident comprising: a single acceleration sensor configured to measure an acceleration of a vehicle to provide an acceleration wave form; and a determination circuit that includes a plastic deformation pulse detection section, an elastic deformation pulse detection section, and a severity determination section, wherein the determination circuit is electrically connected with the acceleration sensor; the plastic deformation pulse detection section is configured to detect a plastic deformation pulse by separating a plastic deformation pulse component having a first frequency range that is caused by damage of individual parts of the vehicle from the acceleration waveform; the elastic deformation pulse detection section is configured to detect an elastic deformation pulse by separating an elastic deformation pulse component having a second frequency range that is caused by damage of the entire vehicle to be lower than the first frequency range from the acceleration waveform; the severity determination section is configured to determine the severity of a collision based on a correlation between a vehicle speed, the plastic deformation pulse, and the elastic deformation pulse; the plastic deformation pulse detection section is configured to calculate a first average acceleration of the plastic deformation pulse in a predetermined time interval; the elastic deformation pulse detection section is configured to calculate a second average acceleration of the elastic deformation pulse in a predetermined time interval; the severity determination section is configured to calculate a weighting factor by dividing an absolute value of the first average acceleration minus the second average acceleration by the second average acceleration; and the severity determination section determines the severity of a collision using the weighting factor.