System and method for drift compensation in a seat load sensing system
View Patent ↗A method ( 60 ) for adjusting a sensed load W(s) of a vehicle seat weight sensing system ( 10 ) includes the step ( 64 ) of determining a rate of change {dot over (W)}(t),{dot over (W)} avg in the sensed load. The method ( 60 ) also includes the step ( 66 ) of determining the likelihood of drift in the sensed load W(s) in response to the determined rate of change {dot over (W)}(t),{dot over (W)} avg .
1. A method for adjusting a sensed load of a vehicle seat weight sensing system, the method comprising the steps of:
determining a rate of change in the sensed load; and
determining the likelihood of drift in the sensed load in response to the determined rate of change.
2. The method of claim 1 , further comprising the step of adjusting the sensed load in response to the determined likelihood drift in the sensed load.
3. The method of claim 1 , wherein said step of determining a rate of change comprises the steps of:
filtering the sensed load;
sampling the filtered load;
determining a sensed load change as the difference between different samples of the filtered load; and
determining the rate of change as the sensed load change over the period of time between the different samples.
4. The method of claim 3 , wherein said step of filtering the sensed load comprises the step of implementing a moving average filter.
5. The method of claim 1 , wherein said step of determining a rate of change comprises the steps of:
filtering the sensed load;
sampling the filtered load;
averaging samples of the filtered load over an interval;
determining a sensed load change as the difference between different sample averages; and
determining the rate of change as the sensed load change over the period of time between the different sample averages.
6. The method of claim 1 , wherein said step of determining the likelihood of drift in the sensed load comprises the steps of:
comparing the rate of change to predetermined categorical thresholds; and
determining the likelihood of drift in the sensed load based on the threshold category into which the rate of change falls.
7. The method of claim 6 , further comprising the step of adjusting the categorical thresholds in response to determining that the sensed load change and a sensed load adjustment value have the same signs.
8. The method of claim 2 , wherein said step of adjusting the sensed load in response to the determined likelihood of drift in the sensed load comprises the steps of:
determining a sensed load change;
determining a load change coefficient in response to the likelihood of drift in the sensed load;
multiplying the sensed load change by the load change coefficient to determine a sensed load adjustment value; and
adjusting the sensed load by said sensed load adjustment value.
9. The method of claim 2 , wherein said steps of determining a rate of change, determining the likelihood of drift, and adjusting the sensed load are repeated throughout an ignition cycle of the vehicle.
10. A method for adjusting a sensed load of a vehicle seat weight sensing system, the method comprising the steps of:
determining a rate of change in the sensed load; and
adjusting the sensed load compensate for drift in the sensed load in response to the determined rate of change in the sensed load.
11. A vehicle seat weight sensing system comprising:
a seat weight sensor associated with a vehicle seat;
a controller operative to determine a sensed weight on the vehicle seat in response to a sensed load provided by said seat weight sensor, said controller comprising:
means for determining a rate of change in the sensed load;
means for determining the likelihood of drift in the sensed load in response to the determined rate of change.
12. The system of claim 11 , wherein said controller further comprises means for adjusting the sensed load in response to the determined likelihood drift in the sensed load.
13. The system of claim 11 , wherein said means for determining a rate of change further comprises:
means for filtering the sensed load;
means for sampling the filtered load;
means for determining a sensed load change as the difference between different samples of the filtered load; and
means for determining the rate of change as the sensed load change over the period of time between the different samples.
14. The system of claim 13 , wherein said means for filtering the sensed load comprises a moving average filter.
15. The system of claim 11 , wherein said means for determining a rate of change further comprises:
means for filtering the sensed load;
means for sampling the filtered load;
means for averaging samples of the filtered load over an interval;
means for determining a sensed load change as the difference between different sample averages; and
means for determining the rate of change as the sensed load change over the period of time between the different sample averages.
16. The system of claim 11 , wherein said means for determining the likelihood of drift in the sensed load comprises:
means for comparing the rate of change to predetermined categorical thresholds; and
means for determining the likelihood of drift in the sensed load based on the threshold category into which the rate of change falls.
17. The system of claim 16 , wherein said controller further comprises means for adjusting the categorical thresholds in response to determining that the sensed load change and a sensed load adjustment value have the same signs.
18. The system of claim 12 , wherein said means for adjusting the sensed load in response to the determined likelihood of drift in the sensed load comprises:
means for determining a sensed load change;
means for determining a load change coefficient in response to the likelihood of drift in the sensed load;
means for multiplying the sensed load change by the load change coefficient to determine a sensed load adjustment value; and
means for adjusting the sensed load by said sensed load adjustment value.