Occupant classification system and method

1. A system for classifying an occupant located on a vehicle seat comprising:

a plurality of force sensors located beneath the vehicle seat;

a controller, wherein each of the force sensors provides a signal corresponding to the vertical force at each sensor wherein the total vertical force on all the sensors is indicative of the weight of the seat and the occupant of the seat; and

wherein the controller is configured to provide an occupant classification calculation based on the total vertical force on the sensors and to determine whether a measure of the total vertical force on the seat is less than a threshold value, and to transmit a signal indicating a potential error in the occupant classification calculation if the measure is consistently below the threshold value.

2. The system of claim 1 , wherein the controller is configured to identify when the instances are caused by a significant portion of the vertical force on the seat being shunted around one of the sensors by an object positioned beneath the vehicle seat.

3. The system of claim 1 , wherein the controller is configured to identify when the instances are caused by the vertical force on the seat being increased or decreased by a force other than the weight of the seat or the weight of the occupant.

4. The system of claim 1 , wherein the controller is configured to determine whether the total force on the vehicle seat is less than a threshold value.

5. The system of claim 1 , wherein each of the plurality of force sensors is positioned between the vehicle seat and a seat rail.

6. The system of claim 1 , wherein the plurality of force sensors includes at least three sensors positioned under the vehicle seat.

7. The system of claim 1 , wherein the plurality of force sensors include a front sensor and a rear sensor, and wherein each sensor provides a force signal to the controller in a channel.

8. The system of claim 1 , wherein the controller is configured to transmit a faulty system signal in an instance when the vertical forces on the force sensors are not indicative of the weight of the seat and the weight of the occupant located on the vehicle seat.

9. The system of claim 1 , wherein the controller is configured to determine whether an interfering object is influencing the total vertical force determination.

10. The system of claim 1 , further comprising an additional sensor for sensing a vehicle characteristic and wherein the controller is configured to determine the direction of external forces being applied on the vehicle seat based on input from the force sensors and the additional sensor.

11. The system of claim 10 , wherein the additional sensor senses one of vehicle speed, vehicle seat position, vehicle acceleration or seat belt tension.

12. The system of claim 1 , wherein the controller is configured to detect fluctuations in the vertical force on the sensors and determine whether a center of gravity of the fluctuations matches an expected center of gravity corresponding to the occupant classification calculated by the controller.

13. The system of claim 1 , wherein the controller is configured to detect fluctuations in the signals from each of the plurality of force sensors and determine whether an unexpected low level of fluctuations from a single sensor is caused by an interfering object positioned under the seat.

14. A system for classifying an occupant located on a vehicle seat comprising:

a plurality of force sensors located beneath the vehicle seat;

a controller, wherein each of the force sensors provides a signal corresponding to the vertical force at each sensor wherein the total vertical force on all the sensors is indicative of the weight of the seat and the occupant of the seat; and

wherein the controller is configured to provide an occupant classification calculation based on the total vertical force on the sensors and to transmit a faulty system signal if the distribution of the vertical force on the seat as determined from the signals provided by the sensors falls outside of a range of force distribution expected for the calculated occupant class.

15. The system of claim 14 , wherein the controller is configured to compensate for a faulty sensor in the occupant classification calculation.

16. A method for detecting and classifying an occupant located in a vehicle seat comprising:

providing a occupant classification calculation;

providing a plurality of force sensors, each force sensor providing a signal corresponding to the vertical force on that force sensor;

determining the total vertical force on the sensors;

determining whether the total vertical force is less than a threshold value; and

transmitting a signal indicating a potential error in the occupant classification calculation if the total vertical force on the seat is consistently below the threshold value.