Occupant detection system

• US 6,378,900 B1
• Filed: 05/10/2000
• Issued: 04/30/2002
• Est. Priority Date: 05/11/1999
• Status: Expired due to Term

• Current Assignee: Joyson Safety Systems Acquisition, LLC (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Automotive Systems Laboratory, Incorporated (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Stanley, James G., McDonnell, Judson G., Stopper, Robert A. Jr.
• Primary Examiner(s): Mai, Lanna
• Assistant Examiner(s): Ilan, Ruth
• Application Number:
  US09/568,596
• Time in Patent Office: 720 Days
• Field of Search: 280/735, 180/272, 180/273, 701/45
• US Class Current: 280/735
• 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: B60N 2/0028 of a body part, e.g. of an arm or a leg
• CPC Class Codes: B60N 2/0029 for detecting the motion of the occupant
• CPC Class Codes: B60N 2/28 Seats readily mountable on, and dismountable from, existing seats or other parts of the vehicle
• CPC Class Codes: B60N 2/286 forward facing B60N2/2866 takes precedence
• CPC Class Codes: B60N 2/2863 backward facing
• CPC Class Codes: B60N 2210/12 Capacitive; Electric field
• CPC Class Codes: B60N 2210/18 Infrared
• CPC Class Codes: B60N 2210/20 Radar
• CPC Class Codes: B60N 2210/22 Optical; Photoelectric; Lidar [Light Detection and Ranging]
• CPC Class Codes: B60N 2210/26 Ultrasonic, e.g. sonar
• CPC Class Codes: B60N 2220/20 using a deterministic algorithm
• CPC Class Codes: B60R 2021/0034 lying down
• CPC Class Codes: B60R 2021/0037 standing
• CPC Class Codes: B60R 21/01516 using force or pressure sensing means
• CPC Class Codes: B60R 21/01532 using electric or capacitive field sensors
• CPC Class Codes: B60R 21/01534 using electromagneticwaves, e.g. infrared
• CPC Class Codes: B60R 21/01536 using ultrasonic waves
• CPC Class Codes: B60R 21/01556 Child-seat detection systems
• CPC Class Codes: G01B 7/023 for measuring distance between sensor and object G01B7/082 and G01B7/102 take precedence
• CPC Class Codes: G01V 3/088 : operating with electric fields G01V3/082 takes precedence
• CPC Class Codes: G08B 13/26 : by proximity of an intruder causing variation in capacitance or inductance of a circuit
• CPC Class Codes: H03K 17/955 : using a capacitive detector

Abstract

A first electric field sensor in a seat bottom identifies whether there is normally seated, forward facing occupant on a vehicle seat by generating an electric field and sensing the effect of proximate objects thereupon. A second electric field sensor determines if an object is within an at-risk zone proximate to a safety restraint system by sensing from a proximate location the electric field generated by the first electric field sensor, and is responsive to the degree to which an object detected in the at-risk zone is electrostatically coupled to the vehicle seat. A range/proximity sensor may be provided to measure the proximity of an occupant to the seat back, so as to accommodate occupant movement prior to the deployment of the safety restraint system, and to improve occupant discrimination.

Claims

1. A system for detecting an occupant in a vehicle, comprising:

a. a first electric field sensor comprising at least one first electrode mountable in a seat bottom of a vehicle seat, wherein said at least one first electrode is operatively coupled to at least one first applied signal so as to generate an electric field responsive to said at least one first applied signal, at least one said first electrode is operatively coupled to a first receiver, said first receiver outputs at least one first received signal responsive to said electric field at said at least one first electrode operatively coupled to said first receiver, and said at least one first received signal is responsive to at least one electric-field-influencing property of a first object proximate to said first electric field sensor; and

b. a second electric field sensor comprising at least one second electrode proximate to a safety restraint system, wherein said at least one second electrode is operatively coupled to a second receiver, said second receiver outputs at least one second received signal, said at least one second received signal is responsive to the electric field influencing at least one of said at least one second electrode whereby said electric field is generated by said first electric field sensor, said at least one second received signal is responsive to a proximity of either said first object or a second object to said at least one second electrode, and said at least one second received signal is responsive to an electrostatic coupling of either said first object or said second object to said first electric field sensor.

2. A system for detecting an occupant in a vehicle as recited in claim 1, wherein said at least one first electrode is shaped so that a capacitance of said at least one first electrode with respect to a circuit ground is substantially greater for a seating condition selected from an occupant seated in substantially normal seating position on the vehicle seat and a large body immediately above said seat bottom;

than for a seating condition selected from an empty said vehicle seat, an infant seat on said vehicle seat, a child seat on said vehicle seat, a booster seat on said vehicle seat, an infant seated in an infant seat on said vehicle seat, a child seated in a child seat on said vehicle seat, a child seated in a booster seat on said vehicle seat, and an occupant on said vehicle seat in a position that is substantially different from a normal seating position.

3. A system for detecting an occupant in a vehicle as recited in claim 1, wherein said at least one first electrode is substantially the same size as a region to be sensed on said vehicle seat.

4. A system for detecting an occupant in a vehicle as recited in claim 1, wherein said at least one first electrode is mounted under a seat cover of said vehicle seat.

5. A system for detecting an occupant in a vehicle as recited in claim 1, wherein said at least one first electrode is mounted above a foam cushion in said vehicle seat.

6. A system for detecting an occupant in a vehicle as recited in claim 1, wherein said at least one first electrode is mounted proximate to the location of an object selected from an infant seat on said vehicle seat, a child seat on said vehicle seat, a booster seat on said vehicle seat, and an occupant seated on said vehicle seat.

7. A system for detecting an occupant in a vehicle as recited in claim 1, wherein said vehicle seat comprises a seat frame, and said seat frame is connected to said circuit ground.

8. A system for detecting an occupant in a vehicle as recited in claim 1, wherein said first applied signal is selected from at least one oscillating signal and at least one pulsed signal.

9. A system for detecting an occupant in a vehicle as recited in claim 1, wherein said at least one first electrode comprises a plurality of first electrodes, said plurality of first electrodes are operatively coupled to said first receiver, and said at least one first received signal is responsive to the distribution of an object on said vehicle seat.

10. A system for detecting an occupant in a vehicle as recited in claim 9, wherein said at least one first received signal comprises a plurality of first received signals from different first electrodes.

11. A system for detecting an occupant in a vehicle as recited in claim 1, wherein said at least one electric-field-influencing property comprises a dielectric characteristic.

12. A system for detecting an occupant in a vehicle as recited in claim 1, wherein said at least one first received signal is responsive to a capacitance of at least one of said at least one first electrode with respect to at least another said first electrode.

13. A system for detecting an occupant in a vehicle as recited in claim 1, wherein said at least one first received signal is responsive to a capacitance of at least one of said at least one first electrode with respect to a circuit ground.

14. A system for detecting an occupant in a vehicle as recited in claim 1, wherein said first receiver further comprises:

a. a reference capacitor wherein a capacitance of said reference capacitor is stable over a range of temperatures; and

b. a switch for switching said reference capacitor in place of at least one of said at least one first electrode operatively coupled to said first receiver, wherein a measurement of said reference capacitor is compared with a measurement of said first electric field sensor and said first received signal is calibrated responsive to said comparison.

15. A system for detecting an occupant in a vehicle as recited in claim 14, wherein a decision threshold is adapted responsive to said comparison.

16. A system for detecting an occupant in a vehicle as recited in claim 1, wherein said first electric field sensor further comprises at least one third electrode and at least one fourth electrode, wherein said at least one third electrode is located between said at least one first electrode and said at least one fourth electrode, and said at least one third electrode is operatively coupled to a second applied signal.

17. A system for detecting an occupant in a vehicle as recited in claim 16, wherein said at least one third electrode is substantially the same size as said at least one first electrode.

18. A system for detecting an occupant in a vehicle as recited in claim 16, wherein said second applied signal is substantially the same as said first applied signal.

19. A system for detecting an occupant in a vehicle as recited in claim 16, wherein said at least one fourth electrode is located between said at least one first electrode and a foam cushion of said vehicle seat.

20. A system for detecting an occupant in a vehicle as recited in claim 16, wherein said at least one fourth electrode is substantially the same size as said at least one first electrode.

21. A system for detecting an occupant in a vehicle as recited in claim 16, wherein said at least one fourth electrode is operatively connected to a circuit ground.

22. A system for detecting an occupant in a vehicle as recited in claim 16, wherein said at least one fourth electrode is operatively connected to a third applied signal, and said third applied signal is a circuit ground potential.

23. A system for detecting an occupant in a vehicle as recited in claim 1, further comprising a controller operatively coupled to said first electric field sensor and to said second electric field sensor, wherein said controller discriminates responsive to said first received signal the type of object on said vehicle seat and controls the actuation of a safety restraint system responsive thereto.

24. A system for detecting an occupant in a vehicle as recited in claim 23, wherein said controller distinguishes a body part of an occupant seated on said vehicle seat from a body part of an occupant not seated directly on said vehicle from said second received signal, and controls the actuation of a safety restraint system responsive thereto.

25. A system for detecting an occupant in a vehicle as recited in claim 24, wherein said controller disables said safety restraint system if a body part is detected from an occupant not seated directly on said vehicle seat.

26. A system for detecting an occupant in a vehicle as recited in claim 23, wherein said controller disables said safety restraint system if said first electric field sensor senses an occupant seated on said vehicle seat and said second received signal is less than a first threshold.

27. A system for detecting an occupant in a vehicle as recited in claim 23, wherein said controller enables said safety restraint system if said first electric field sensor senses an occupant seated on said vehicle seat and said second received signal is greater than a second threshold.

28. A system for detecting an occupant in a vehicle as recited in claim 23, wherein said controller disables said safety restraint system if said first electric field sensor senses an occupant seated on said vehicle seat and said second received signal is greater than a second threshold for a period of time greater than a third threshold.

29. A system for detecting an occupant in a vehicle as recited in claim 1, further comprising a range/proximity sensor mountable within the seat back of a vehicle seat, wherein said range/proximity sensor when mounted in the seat back of said vehicle seat is responsive to a torso of an occupant proximate to said seat back.

30. A system for detecting an occupant in a vehicle as recited in claim 29, wherein said range/proximity sensor is selected from a third electric field sensor comprising at least one fifth electrode, a capacitive sensor, a radar sensor, an optical range sensor, an active infrared sensor, a passive infrared sensor, a vision sensor, an ultrasonic range sensor, and an inductive sensor.

31. A system for detecting an occupant in a vehicle as recited in claim 29, wherein said range/proximity sensor provides a measure of distance from said seat back to a torso of an occupant.

32. A system for detecting an occupant in a vehicle as recited in claim 29, further comprising a controller operatively coupled to said first electric field sensor and to said second electric field sensor, wherein responsive to said first received signal said controller discriminates the type of object on said vehicle seat and controls the actuation of a safety restraint system responsive thereto and if said second electric field sensor detects an object within an at-risk zone proximate to said safety restraint system then said controller controls the actuation of a safety restraint system responsive to said range/proximity sensor.

33. A system for detecting an occupant in a vehicle, comprising:

a. a means for generating an electric field proximate to a seat bottom of a vehicle seat;

b. a means for sensing an object on said seat bottom of said vehicle seat from the influence of said object on said electric field;

c. a means for sensing said electric field proximate to a safety restraint system;

d. a means for detecting whether an object proximate to a safety restraint system is seated on said vehicle seat from said means for sensing said electric field proximate to a safety restraint system; and

e. a means for controlling the actuation of said safety restraint system responsive to said means for sensing an object and responsive to said means for sensing said electric field.

34. A method of detecting an occupant in a vehicle, comprising:

a. generating an electric field proximate to a seat bottom of a vehicle seat;

b. sensing an object on said seat bottom of said vehicle seat from the influence of said object on said electric field;

c. sensing said electric field proximate to a safety restraint system;

d. detecting whether an object proximate to a safety restraint system is seated on said vehicle seat from the sensed electric field proximate to a safety restraint system; and

e. controlling the actuation of said safety restraint system responsive to the sensed object and responsive to the sensed electric field.