Method and system for determining weight and position of a vehicle seat occupant

• US 7,082,360 B2
• Filed: 03/16/2001
• Issued: 07/25/2006
• Est. Priority Date: 02/04/1994
• Status: Expired due to Fees

• Current Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Original Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Inventors: Lichtinger, Harold, Oestreicher, Ralf, Reich, Dan, Homann, Michelle, Morell, Scott
• Primary Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US09/810,943
• Publication Number:
  US 20020120379A1
• Time in Patent Office: 1,957 Days
• Field of Search: 701/36, 701/45, 701/49, 701/29, 701/35, 280/734, 280/735, 297/217.2, 180/268, 180/271, 180/273, 340/666, 340/667, 340/668, 702/101, 702/102
• 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: B60N 2/0025 by using weight measurement
• CPC Class Codes: B60N 2/0027 for detecting the position of the occupant or of occupant's body part
• CPC Class Codes: B60N 2/0031 mounted on the frame
• CPC Class Codes: B60N 2/0035 characterised by the sensor data transmission, e.g. wired connections or wireless transmitters therefor; characterised by the sensor data processing, e.g. seat sensor signal amplification or electric circuits for providing seat sensor information
• CPC Class Codes: B60N 2210/42 Strain gauges
• CPC Class Codes: B60R 21/01516 using force or pressure sensing means
• CPC Class Codes: B60R 21/0152 using strain gauges
• CPC Class Codes: H04N 1/00681 Detecting the presence, position or size of a sheet or correcting its position before scanning H04N1/047 takes precedence; mode signalling H04N1/333; skew detection or correction in image signals H04N1/3878
• CPC Class Codes: H04N 1/0071 Width
• CPC Class Codes: H04N 1/00713 Length
• CPC Class Codes: H04N 1/00779 Adjusting settings, e.g. mode, feeding rate or type of paper

Abstract

A method and system for determining weight and/or position of a vehicle seat occupant to be used for controlling the reaction of a safety restraint system. A plurality of spaced weight sensors are disposed between a seating surface and seat mounting surface to provide output signals indicative of an applied weight on each sensor. The sensors are spaced such that the sensors measure the weight applied to a seat back and the seating surface. A controller calculates the weight and/or position of the seat occupant in response to the output signals of the sensors. The controller sends the weight and position of the seat occupant to the safety restraint system to be used to tailor or suppress the reaction of the safety restraint system.

Claims

1. A weight sensing apparatus for a vehicle seat comprising:

a plurality of sensors each including a mounting portion for attachment to a vehicle seat structure and a deflectable portion that deflects in response to a weight force applied to the vehicle seat structure to generate a weight signal wherein each of said sensors includes a sensor interface circuit mounted to said deflectable portion that develops a pulse width modulation signal indicative of the weight applied to said corresponding sensor;

at least one strain gauge mounted to said deflectable portion of each of said sensors; and

a controller for receiving said weight signals from said sensors to determine seat occupant weight.

2. An apparatus as in claim 1 wherein said at least one strain gauge is a plurality of strain gauges mounted in a predetermined spaced relationship to each other on said deflectable portion.

3. An apparatus as in claim 1 wherein said seat structure is a seat pan.

4. An apparatus as in claim 3 wherein each of said sensors includes a support portion mounted to a vehicle seat track member such that said deflectable portion is positioned between said mounting and support portions.

5. An apparatus as in claim 3 wherein said seat pan is rectangular in shape defining four corners and said plurality of sensors is comprised of four sensors with one of said sensors mounted at each of said corners.

6. An apparatus as in claim 1 including a safety restraint device controlled by said controller in response to seat occupant weight.

7. An apparatus as in claim 6 wherein said safety restraint device is not deployed if seat occupant weight is below a predetermined weight.

8. An apparatus as in claim 1 wherein said sensor interface circuit includes a pulse width modulation circuit and a two-stage signal amplifier for amplifying said pulse width modulation signal to a readable level.

9. An apparatus as in claim 8 including a temperature control circuit for compensating for varying temperatures within the sensor interface circuit.

10. An apparatus as in claim 1 wherein said controller calculates weight of an occupant by sampling the response of each of said sensors to a weight applied to said vehicle seat structure.

11. A method for determining seat occupant weight including the steps of:

mounting a plurality of sensors to a vehicle structure with each sensor including a deflectable portion that deflects in response to a weight force applied to the vehicle seat structure;

mounting a strain gauge to the deflectable portion of each sensor;

associating a sensor interface circuit with each sensor mounted to the deflectable portion and developing a pulse width modulation signal indicative of the weight applied to the corresponding sensor;

generating a weight signal from each of the sensors in response to the deflection; and

determining seat occupant weight from the signals.

12. A method as in claim 11 further comprising the step of controlling a safety restraint device based on the seat occupant weight.

13. A method as in claim 12 further comprising the step of preventing deployment of the safety restraint device if the seat occupant weight is below a predetermined weight.

14. A method as in claim 11 further comprising the step of determining a center of gravity of the seat occupant from the signals.

15. A method as in claim 14 further comprising the step of controlling a safety restraint device based on the seat occupant weight and center of gravity.

16. A method as in claim 11 wherein the seat structure is a seat pan and the method further comprises the step of mounting the sensors between the seat pan and a seat track assembly.

17. A method as in claim 11 including the steps of providing the sensor interface circuit with a two-stage signal amplifier and amplifying the pulse width modulation signals for each sensor to a readable level.

18. A method as in claim 17 including the step of providing the sensor interface circuit with a temperature control circuit for compensating for varying temperatures within the sensor interface circuit.

19. A method as in claim 11 including the step of calculating weight of an occupant by sampling the response of each of the sensors to at weight applied to the vehicle seat structure.

20. A weight sensing apparatus for a vehicle seat comprising:

a plurality of sensors each including a mounting portion for attachment to a vehicle seat structure comprising a seat pan, a deflectable portion that deflects in response to a weight force applied to the vehicle seat structure to generate a weight signal, and a support portion mounted to a vehicle seat track member such that said deflectable portion is positioned between said mounting and support portions;

a plurality of strain gauges mounted to said deflectable portion of each of said sensors wherein said plurality of strain gauges comprises a first pair of strain gauges diametrically opposite from each other and mounted directly to said deflectable portion at a first position and a second pair of strain gauges diametrically opposite from each other and mounted directly to said deflectable portion at a section position spaced apart from said first position; and

a controller for receiving said weight signals from said sensors to determine seat occupant weight.

21. An apparatus as in claim 20 wherein both of said first pair of strain gauges are positioned between said second pair of strain gauges on a common surface of said deflectable portion.

22. A weight sensing apparatus for a vehicle seat comprising:

a plurality of sensors each including a mounting portion for attachment to a vehicle seat structure and a deflectable portion that deflects in response to a weight force applied to the vehicle seat structure to generate a weight signal;

at least one strain gauge mounted to said deflectable portion of each of said sensors; and

a controller for receiving said weight signals from said sensors to determine seat occupant weight wherein said controller calculates weight of an occupant by sampling the response of each of said sensors to a weight applied to said vehicle seat structure and wherein said controller samples said sensors approximately every thirty milliseconds.

23. A weight sensing apparatus for a vehicle seat comprising:

a plurality of sensors each including a mounting portion for attachment to a vehicle seat structure and a deflectable portion that deflects in response to a weight force applied to the vehicle seat structure to generate a weight signal;

at least one strain gauge mounted to said deflectable portion of each of said sensors; and

a controller for receiving said weight signals from said sensors to determine seat occupant weight wherein said controller calculates weight of an occupant by sampling the response of each of said sensors to a weight applied to said vehicle seat structure and wherein said controller determines the weight by computing a biased average of each of said sensors over time and summing all of said biased averages together to obtain a total weight.

24. An apparatus as in claim 23 wherein said controller determines occupant center of gravity based on measurements taken by said sensors and determines occupant position based on total weight and center of gravity.

25. An apparatus as in claim 24 wherein said controller generates a correction factor based on said center of gravity and determines a corrected occupant weight by modifying said total weight by said correction factor.

26. A method for determining seat occupant weight including the steps of:

mounting a plurality of sensors to a vehicle structure with each sensor including a deflectable portion that deflects in response to a weight force applied to the vehicle seat structure;

mounting a strain gauge to the deflectable portion of each sensor

generating a weight signal from each of the sensors in response to the deflection; and

determining seat occupant weight from the signals by calculating weight of an occupant by sampling the response of each of the sensors to a weight applied to the vehicle seat structure and including sampling the sensors approximately every thirty milliseconds.

27. A method for determining seat occupant weight including the steps of:

mounting a plurality of sensors to a vehicle structure with each sensor including a deflectable portion that deflects in response to a weight force applied to the vehicle seat structure;

mounting a strain gauge to the deflectable portion of each sensor

generating a weight signal from each of the sensors in response to the deflection; and

determining seat occupant weight from the signals by calculating weight of an occupant by sampling the response of each of the sensors to a weight applied to the vehicle seat structure and including determining the weight by computing a biased average of each of the sensors over time and summing all of the biased averages together to obtain a total weight.

28. A method as in claim 27 including the steps of determining occupant center of gravity based on measurements taken by the sensors and determining occupant position based on total weight and center of gravity.

29. A method as in claim 28 including the steps of generating a correction factor based on the center of gravity and determining a corrected occupant weight by modifying the total weight by the correction factor.