Patent ID: 6764095
Filing Date: 2004-07-20
Classification: B60R

Abstract:
A method for measuring the actual mass of a seat occupant secured to a seat of a vehicle by a seat belt, the method comprising the steps of:measuring a total downward force on a seat contributed by a seat occupant and seat belt tension; providing a first strain gauge mounted on a first attachment bolt used to couple the seat belt to a first anchor piece; providing a second strain gauge mounted on a second attachment bolt used to couple the seat belt to a second anchor piece; measuring a change in resistance of said first strain gauge, wherein said change of resistance of said first strain gauge is a result of the bending of said first attachment bolt in response to the degree of tension in the seat belt at a location near said first anchor piece; sending a first signal from said first strain gauge to a seat belt tension sensor module proportional to a change in resistance of said first strain gauge; measuring a chance in resistance of said second strain gauge, wherein said change of resistance is a result of the bending of said second attachment bolt in response to the degree of tension in the seat belt at a location near said second anchor piece; sending a second signal from said second strain gauge to said seat belt tension sensor module proportional to a change in resistance of said second strain gauge; converting said first signal and said second signal to a load signal within said seat belt tension sensor module, said load signal proportional to an algebraic sum of said first signal and said second signal; and sending the load signal to a seat weight module, wherein the seat weight module determines a vertical component of force contributed by seat belt tension as a function of the load signal; measuring a vertical component of force contributed by seat belt tension; and subtracting the vertical component of force from the total downward force to determine a weight, and hence the actual mass, of the seat occupant.