Vehicle occupant presence and position sensing system

• US 6,584,387 B1
• Filed: 07/23/2001
• Issued: 06/24/2003
• Est. Priority Date: 11/23/1993
• Status: Expired due to Fees

• Current Assignee: Peter Norton
• Original Assignee: Peter Norton
• Inventors: Norton, Peter
• Primary Examiner(s): Beaulieu, Yonel
• Application Number:
  US09/911,251
• Time in Patent Office: 701 Days
• Field of Search: 701/45, 701/46, 280/728.1, 280/734, 280/735
• US Class Current: 701/45
• CPC Class Codes: B60R 21/01532 using electric or capacitive field sensors
• CPC Class Codes: B60R 21/01554 Seat position sensors
• CPC Class Codes: B60R 21/01556 Child-seat detection systems

Abstract

The invention characterizes a seat occupant. The position of a seat occupant relative to the seat is determined and the position of the seat relative to the vehicle determines the location of the seat occupant relative to the vehicle. The position and other characteristics of the seat occupant are determined from the magnitude and Q of capacitance between electrodes in the seat, thereby distinguishing between a seat occupied by a normally seated person and certain other circumstances wherein deployment of airbags is not desired. The position of the occupant relative to the seat, the weight of the seat occupant, whether the seat belt is latched, the track position and recline angle of the vehicle seat and vehicle deceleration during a crash are used to estimate the position of the occupant relative to a deploying airbag as the occupant moves toward the airbag during the crash.

Claims

1. In a vehicle having a microprocessor and occupant protection means for protecting an occupant of said vehicle, wherein said occupant protection means is controlled by said microprocessor, the improvement comprising:

a vehicle seat comprising a seat back, a seat cushion, and sensing means for providing data for ascertaining the position of an occupant of said seat with respect to a reference frame fixed with respect to the structure of said vehicle, and

a calculator adapted to calculate said position of said occupant of said seat from input comprising said data, and

means for transmitting said position of said occupant of said seat to said microprocessor.

2. The invention as defined by claim 1 wherein said sensing means comprises:

one or more sensors selected for providing data for ascertaining the position of said seat back and said seat cushion with respect to said reference frame, and

one or more sensors selected for providing data for ascertaining the position of said occupant of said seat with respect to said seat back and said seat cushion.

3. The invention as defined by claim 2 wherein:

said seat is movable on a track, and

said sensors selected for providing data for ascertaining the position of said seat back and said seat cushion with respect to said reference frame comprises

a position sensor for indicating the position of said seat on a seat track.

4. The invention as defined by claim 2 wherein

said sensors selected for providing data for ascertaining the position of said seat back and said seat cushion with respect to said reference frame comprises

a sensor for indicating the recline angle of said seat back.

5. The invention as defined by claim 2 wherein said sensors selected for providing data for ascertaining the position of said occupant of said seat with respect to said seat back and said seat cushion comprises:

an electrode in said seat back,

an electrode in said seat cushion, and

a sensor responsive to the capacitance between said electrodes.

6. The invention as defined by claim 5 wherein

said capacitance sensor comprises:

means for applying an electric signal to one of said electrodes, and

means for measuring the displacement current between said one of said electrodes and the other of said electrodes.

7. The invention as defined by claim 6 wherein

said means for measuring the displacement current comprises:

a resistance connected such that said displacement current passes through said resistance, and

means for measuring the voltage across said resistance.

8. The invention as defined by claim 2 wherein

said sensors selected for providing data for ascertaining the position of said occupant of said seat with respect to said seat back and said seat cushion comprises

a sensor for providing first data for ascertaining a first distance between the back of the occupant of said seat and said seat back.

9. The invention as defined by claim 8 wherein said sensor for providing first data for ascertaining a first distance between the back of said seat occupant and said seat back comprises:

a first electrode in said seat back,

a first electrode in said seat cushion, and

a capacitance sensor for measuring a first capacitance between said first electrodes.

10. The invention as defined by claim 9 wherein:

said sensors selected for providing data for ascertaining the position of said occupant of said seat with respect to said seat back and said seat cushion also comprises

a sensor for providing data for ascertaining a second distance between the back of said occupant of said seat and said seat back comprising;

a second electrode in said seat back, and

a sensor responsive to the capacitance between said second electrode and said electrode in said seat cushion.

11. The invention as defined by claim 10 wherein:

said microprocessor is adapted to calculate said first distance from said first capacitance, said first distance defining a first point forward of said seat back,

said microprocessor is adapted to calculate said second distance from said second capacitance, said second distance defining a second point forward of said seat back,

said microprocessor uses said two points to define in a reference frame fixed with respect to the structure of said vehicle a plane surface having said first point and second point thereon, and also having thereon a horizontal line extending transverse to the direction of forward movement of said vehicle, and

said position of an occupant of said seat with respect to a reference frame fixed with respect to the structure of said vehicle is the position of a human having thighs adjacent said seat cushion and the back adjacent said plane surface.

12. The invention as defined by claim 11, and including

a weight sensor responsive to the weight of said seat occupant, and wherein

said microprocessor assumes the dimensions of said human are average dimensions of humans having the weight estimated by said weight sensor.

13. The invention as defined by claim 8 wherein

said sensor for providing first data for ascertaining a first distance between the back of said seat occupant and said seat back comprises:

a first emitter for generating a first sound, a first receiver for receiving an echo of said first sound, and a timer for measuring the time between when said first sound is generated and the time when said echo of said first sound is received.

14. The invention as defined by claim 8 wherein

said sensors selected for providing data for ascertaining the position of said occupant of said seat with respect to said seat back and said seat cushion comprises

a sensor for providing second data for ascertaining said first distance between the back of said occupant of said seat and said seat back.

15. The invention as defined by claim 14 wherein said sensor for providing second data comprises:

a second emitter for generating a second sound, a second receiver for receiving an echo of said second sound, and a timer for measuring the time between when said second sound is generated and the time when said echo of said second sound is received, whereby

data are provided for making two independent ascertainments of said first distance between the back of said seat occupant and said seat back.

16. The invention as defined by claim 14 wherein:

said calculator is adapted to calculate a first occupant location from said first data,

said calculator is also adapted to calculate a second occupant location from said second data, and

said calculator is adapted to use said first and second occupant locations when calculating said position.

17. The invention as defined by claim 14 wherein:

said first data for ascertaining said first distance is used for said ascertaining the position of said occupant of said seat with respect to said seat back and said seat cushion when said first distance is less than a predetermined distance, and

said second data for ascertaining said first distance is used for said ascertaining the position of said occupant of said seat with respect to said seat back and said seat cushion when said first distance is greater than said predetermined distance.

18. The invention as defined by claim 1, and including

an accelerometer responsive to decelerations resulting from a crash, and wherein:

said calculator is connected for receiving data from said accelerometer for computing values of the second integral of said deceleration as said crash progresses, and

said calculator is adapted to use said values of said second integral when calculating said position.

19. The invention as defined by claim 18, and wherein:

said calculator comprises means for calculating the velocity of said occupant of said seat with respect to a reference frame fixed with respect to the structure of said vehicle, and

said calculator is adapted to transmit said velocity to said microprocessor.

20. The invention as defined by claim 18, and including

a seat belt for restraining said occupant of said seat, and wherein:

said seat belt comprising a latch,

said latch is adapted to provide a seat belt latched signal indicating if said seat belt latch is or is not latched, and

said calculator is adapted to said use said values only when said seat belt latched signal indicates said seat belt is not latched.

21. The invention as defined by claim 8, and including

an accelerometer responsive to deceleration resulting from a crash, and wherein:

said calculator is connected for receiving data from said accelerometer for computing values of the second integral of said deceleration as said crash progresses, and

said calculator is adapted to use said values of said second integral to calculate said position.

22. The invention as defined by claim 8, wherein

said sensors for providing sufficient data for ascertaining the position of said seat occupant with respect to said seat back and said seat cushion comprises

a sensor for providing second data for ascertaining a second distance between the back of said seat occupant and said seat back, and wherein:

said microprocessor is adapted to ascertain said first distance from said first data and said second distance from said second data,

said microprocessor is adapted to use said first distance and said second distance to define two points in a reference frame fixed with respect to the structure of said vehicle,

said two points defining a plane surface containing said two points and a horizontal line extending transverse to the direction of forward movement of said vehicle, and

said position of an occupant of said seat with respect to a reference frame fixed with respect to the structure of said vehicle is the position of a human having thighs adjacent said seat cushion and a back adjacent said plane surface.

23. In a vehicle having decision making means for making decisions and occupant protection means for protecting an occupant of said vehicle, wherein said occupant protection means is controlled by said decision making means, the improvement comprising:

a vehicle seat comprising capacitor electrodes,

seat occupant categorizing means responsive to capacitance between said capacitor electrodes by categorizing an occupant of said seat into one of at least three categories, and

means for transmitting said category to said decision making means.

24. The invention as defined by claim 23 wherein said seat occupant categorizing means is responsive to both the magnitude and Q of the capacitance between said capacitor electrodes.

25. The invention as defined by claim 23 wherein said seat occupant categorizing means causes a displacement current to flow between said capacitor electrodes, and

said occupant categorizing means is responsive to said displacement current by categorizing said occupant of said seat into one of at least three categories.

26. The invention as defined by claim 25, wherein said seat occupant categorizing means is responsive to both the magnitude and phase of said displacement current, whereby

said occupant categorizing means is responsive to both the magnitude and Q of said capacitance between said capacitor electrodes.

27. In a vehicle having decision making means for making decisions and occupant protection means for protecting an occupant of said vehicle, wherein said occupant protection means is controlled by said decision making means, the improvement comprising:

a vehicle seat comprising capacitor electrodes,

means for causing displacement current to flow between said capacitor electrodes,

means responsive to said displacement current by categorizing an occupant of said seat into one of at least three categories, and

means for transmitting said category to said decision making means.