Occupant restraint apparatus and method of controlling occupant restraint apparatus

An occupant restraint apparatus for use on a vehicle, comprising:

• an impact energy absorbing mechanism for preventing a seat belt from being paid out to restrain an occupant in an emergency and allowing the seat belt to be paid out when a load in excess of a preset load is applied to said seat belt;
• length detecting means for detecting a paid-out length of said seat belt when said impact energy absorbing mechanism is operated;
• paid-out acceleration calculating means for calculating a paid-out acceleration of said seat belt from the paid-out length detected by said length detecting means;
• vehicle acceleration calculating means for detecting a speed of the vehicle with respect to a ground surface on which said vehicle runs and calculating an acceleration of the vehicle with respect to the ground surface, or vehicle acceleration detecting means for detecting an acceleration of the vehicle with respect to the ground surface;
• and
• occupant acceleration calculating means for calculating an acceleration of said occupant with respect to said ground surface based on the calculated paid-out acceleration and the calculated or detected acceleration of the vehicle.

A method of controlling an occupant restraint apparatus for use on a vehicle which has an impact energy absorbing mechanism for preventing a seat belt from being paid out to restrain an occupant in an emergency and allowing the seat belt to be paid out when a load in excess of a preset load is applied to said seat belt, comprising the steps of:

• detecting a paid-out length of said seat belt when said impact energy absorbing mechanism is operated;
• calculating a paid-out speed of said seat belt from the detected paid-out length;
• detecting a speed of the vehicle with respect to a ground surface on which said vehicle runs;
• and
• calculating an acceleration of said occupant with respect to said ground surface based on the calculated paid-out speed and the detected speed of the vehicle.

A method of controlling an occupant restraint apparatus for use on a vehicle which has an impact energy absorbing mechanism for preventing a seat belt from being paid out to restrain an occupant in an emergency and allowing the seat belt to be paid out when a load in excess of a preset load is applied to said seat belt, comprising the steps of:

• detecting a paid-out length of said seat belt when said impact energy absorbing mechanism is operated;
• calculating a paid-out acceleration of said seat belt from the detected paid-out length;
• detecting a speed of the vehicle with respect to a ground surface on which said vehicle runs and calculating an acceleration of the vehicle with respect to the ground surface, or detecting an acceleration of the vehicle with respect to the ground surface;
• and
• calculating an acceleration of said occupant with respect to said ground surface based on the calculated paid-out acceleration and the calculated or detected acceleration of the vehicle.