Seat belt tension prediction

A method for predicting seatbelt tension in a vehicle having a seat, an accelerometer rigidly secured to said vehicle in proximity to the seat, said accelerometer having an output signal responsive to a vertical acceleration of said vehicle, a seat weight sensor having an output signal responsive to a force exerted by a mass acting on the seat, and a processor having a first input operatively coupled to the output signal of said accelerometer and a second input operatively coupled to the output signal of said weight sensor comprising:

• a.) measuring an actual variation in force due to vertical acceleration exerted on the seat over a predetermined time period;
• b.) calculating an average mass on the seat;
• c.) calculating a predicted variation in force due to vertical acceleration exerted on the seat by multiplying the average mass on the seat by the variation in vertical acceleration over a predetermined time period;
• and
• d.) dividing the actual variation in force by the predicted variation in force whereby a quotient represents normalized seatbelt tension.

A method for predicting seatbelt tension in a vehicle having a seat, an accelerometer rigidly secured to said vehicle in proximity to the seat, said accelerometer having an output signal responsive to a vertical acceleration of said vehicle, a seat weight sensor having an output signal responsive to a force exerted by a mass on the seat, and a processor having a first input operatively coupled to the output signal of said accelerometer and a second input operatively coupled to the output signal of said weight sensor comprising:

• a.) measuring the force due to vertical acceleration exerted on the seat at discrete time intervals;
• b.) calculating an average mass on the seat;
• c.) calculating at discrete time intervals a predicted force acting on the seat due to vertical acceleration, assuming the tension in said seat belt is zero;
• and
• d.) calculating at discrete time intervals a difference between the measured force exerted on the seat and the predicted force whereby the difference is indicative of seat belt tension.

A method for predicting seatbelt tension in a vehicle having a seat, an accelerometer rigidly secured to said vehicle in proximity to the seat, said accelerometer having an output signal responsive to a vertical acceleration of said vehicle, a seat weight sensor having an output signal responsive to a force exerted by a mass on the seat, and a processor having a first input operatively coupled to the output signal of said accelerometer and a second input operatively coupled to the output signal of said weight sensor comprising:

• a.) measuring the force due to vertical acceleration exerted on the seat at discrete time intervals;
• b.) calculating an average mass on the seat;
• c.) measuring the vertical acceleration acting on said vehicle at discrete time intervals;
• d.) calculating at discrete time intervals a predicted force exerted on the seat by multiplying the vertical acceleration at each time interval by the average mass, assuming the tension in said seat belt is zero;
• and
• e.) calculating at discrete time intervals a ratio between the measured force exerted on the seat and the predicted force exerted on the seat whereby the ratio is indicative of seat belt tension.