Occupant Detection System with Environmental Compensation

• US 20090271076A1
• Filed: 04/30/2009
• Published: 10/29/2009
• Est. Priority Date: 04/28/2008
• Status: Active Grant

• Current Assignee: Aptiv Technologies AG
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Griffin, Dennis P.
• Granted Patent: US 8,237,455 B2
• Time in Patent Office: Days
• US Class Current: 701/45
• CPC Class Codes: B60N 2/002 Seats provided with an occupancy detection means mounted therein or thereon detection means responsive to presence or absence of children B60N2/266
• CPC Class Codes: B60R 21/01532 using electric or capacitive field sensors
• CPC Class Codes: G01G 19/4142 for controlling activation of safety devices, e.g. airbag systems electrical circuits for triggering safety arrangements in case of vehicle accidents B60R21/015

Abstract

An occupant detection system includes an electrode in communication with a detector circuit that detects the impedance of the electrode and compensates for environmental conditions, such as humidity or moisture, based on the impedance measurement. Such environmental conditions may interfere with the occupant detection system'"'"'s ability to detect the presence and/or size of an occupant. Typically, environmental conditions change the impedance of the electrode. The impedance is determined by measuring a frequency response of the electrode. The measured frequency response is compared to predetermined frequency response values that correspond to known environmental conditions. The environmental condition may be detected by matching the peak frequency response or average frequency response to in a lookup table.

Claims

1. An occupant detection system comprising:

an electrode disposed in a seat; and

a detector in communication with the electrode and configured to detect an impedance indicative of a load, determine of an environmental condition based on the impedance, and determine an occupant based upon the impedance and the environmental condition.

2. An occupant detection system as set forth in claim 1, wherein the environmental condition is humidity or moisture.

3. An occupant detection system as set forth in claim 1, wherein said impedance is detected by determining a frequency response of said electrode.

4. An occupant detection system as set forth in claim 3, wherein said detector is configured to measure a peak frequency response over a range of frequencies.

5. An occupant detection system as set forth in claim 3, wherein said detector is configured to measure an average frequency response over a range of frequencies.

6. An occupant detection system as set forth in claim 1, said detector comprising a signal generator, wherein said signal generator is configured to generate a first signal at a first frequency and a second signal at a second frequency.

7. An occupant detection system as set forth in claim 6, said detector further comprising a voltage detection circuit in communication with said signal generator, and wherein said voltage detection circuit is configured to detect a voltage at a plurality of different frequencies.

8. An occupant detection system as set forth in claim 7, said detector further comprising a signal processor in communication with said voltage detection circuit.

9. An occupant detection system as set forth in claim 8, wherein said signal processor is configured to measure a peak frequency response of said electrode.

10. An occupant detection system as set forth in claim 9, wherein said signal processor is configured to compare the peak frequency response to a plurality of predetermined values stored in a lookup table to determine whether the environmental condition is present.

11. An occupant detection system as set forth in claim 8, wherein said signal processor is configured to measure an average frequency response of said electrode.

12. An occupant detection system as set forth in claim 11, wherein said signal processor is configured to compare the average frequency response to the plurality of predetermined values stored in a lookup table to determine whether the environmental condition is present.

13. An occupant detection system as set forth in claim 9, wherein said signal processor is configured to apply a correlation type filter kernel to data received from said voltage detection circuit.

14. An occupant detection system as set forth in claim 8, wherein said detector includes a control module in communication with said signal processor.

15. An occupant detection system as set forth in claim 14, wherein said control module is configured to receive a signal from said signal processor and detect and compensate for the environmental condition indicated by the signal if the environmental condition is present.

16. An occupant detection system as set forth in claim 14, further comprising an airbag system in communication with said control module, and wherein said control module is configured to enable or disable said airbag system independent of the environmental condition.

17. An occupant detection system as set forth in claim 1, wherein said electrode is further defined as a first electrode and further comprising a second electrode in communication with said detector circuit.

18. A method of detecting an occupant, said method comprising the steps of:

measuring an impedance of an electrode;

determining an environmental condition based on the impedance of the electrode; and

determining an occupant based upon the impedance and the environmental condition.

19. A method of as set forth in claim 18, wherein the environmental condition is humidity or moisture.

20. A method as set forth in claim 18, wherein measuring an impedance of an electrode includes determining a frequency response of said electrode.

21. A method as set forth in claim 20, wherein measuring the frequency response of the electrode includes measuring a peak frequency response over a range of frequencies.

22. A method as set forth in claim 21, wherein detecting the environmental condition includes comparing the peak frequency response to a plurality of predetermined values stored in a lookup table.

23. A method as set forth in claim 20, wherein measuring the frequency response of the electrode includes measuring an average frequency response over the range of frequencies.

24. A method as set forth in claim 23, wherein detecting the environmental condition includes comparing the average frequency response to a plurality of predetermined values stored in a lookup table.

25. A method as set forth in claim 20, wherein measuring the frequency response includes applying a correlation type filter kernel to data measured over the range of frequencies.

26. A method as set forth in claim 18, further comprises generating a signal indicating the presence of the environmental condition.

27. A method as set forth in claim 26, further comprises enabling or disabling an airbag system based upon the determination of an occupant.