Vehicle occupant position sensor utilizing image focus attributes

• US 6,578,869 B2
• Filed: 03/26/2001
• Issued: 06/17/2003
• Est. Priority Date: 03/26/2001
• Status: Expired due to Fees

• Current Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Wallace, Jon K., Cooper, Stephen R. W., Khairallah, Farid, Zayan, Nicholas M.
• Primary Examiner(s): Morris, Lesley D.
• Assistant Examiner(s): Lum, L.
• Application Number:
  US09/817,520
• Publication Number:
  US 20020135165A1
• Time in Patent Office: 813 Days
• Field of Search: 701/45, 280/735, 250/221, 250/559.38
• 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: B60R 21/01538 for image processing, e.g. cameras or sensor arrays
• CPC Class Codes: G06T 7/73 using feature-based methods

Abstract

A vehicle occupant sensor apparatus (34) has an imager (36) that gathers an image of an occupant (12). The image has focus attributes. A focal plane associated with the imager (36) is at a distance from the imager. A 2D high-pass filter (42), a multiple frame temporal filter (46), and a position determination component (52) operate to determine position of the occupant (12) relative to the focal plane (38) via use of the focus attributes.

Claims

1. A vehicle occupant sensor apparatus comprising:

an imager that collects an image of an occupant and that outputs a signal indicative of the collected image, the image having focus attributes, a focal plane associated with said imager being at a distance from said imager;

a two-dimensional high pass filter operatively connected to the imager to provide a signal indicative of high frequency content of the imager signal;

a multiple frame temporal filter operatively connected to the imager to provide a signal indicative of image size conveyed by the imager signal; and

a position determination component operatively connected to said two-dimensional high pass filter and said multiple frame temporal filter to determine position of the occupant relative to the focal plane utilizing the signal indicative of high frequency content of the imager signal and the signal indicative of image size.

2. The vehicle occupant sensor apparatus of claim 1 wherein the high frequency content signal is indicative of a sharpness of the image, the sharpness of the image being a focus attribute that is functionally related to the position of the occupant relative to the focal plane.

3. The vehicle occupant sensor apparatus of claim 1 wherein the image size signal is a focus attribute that is functionally related to the position of the occupant relative to the focal plane.

4. A vehicle occupant sensor apparatus comprising:

means for producing periodic images of an occupant, the periodic images having at least two focus attributes that are functionally related to a position of the occupant relative to a focal plane; and

means for detecting changes in the at least two focus attributes of the periodic signals and, in response to the changes in the at least two focus attributes of the periodic signals, for determining the position of the occupant relative to the focal plane.

5. The vehicle occupant sensor apparatus of claim 4 wherein the means for producing has a location that is spaced from the focal plane by a fixed distance, the means for detecting changes also being responsive to the changes in the at least two focus attributes for determining the position of the occupant relative to the location.

6. The vehicle occupant sensor apparatus of claim 4 wherein the at least two focus attributes include sharpness of the periodic images and apparent size of the occupant in the periodic images.

7. The vehicle occupant sensor apparatus of claim 6 further including first and second filter means for receiving the periodic images from the means for producing periodic images, the first filter means outputting sharpness signals that are indicative of the sharpness of the received periodic images, the second filter means outputting size signals that are indicative of the apparent size of the occupant in the received periodic images.

8. The vehicle occupant sensor apparatus of claim 7 wherein the means for detecting changes receives the sharpness signals and the size signals and detects changes in the received sharpness and size signals for determining the position of the occupant relative to the focal plane.

9. The vehicle occupant sensor apparatus of claim 8 wherein the means for detecting changes determines that the occupant is positioned rearward of the focal plane relative to the means for producing periodic images when the detected changes of the sharpness and size signals indicate an increase in both the sharpness and apparent size of the occupant.

10. The vehicle occupant sensor apparatus of claim 8 wherein the means for detecting changes determines that the occupant is positioned rearward of the focal plane relative to the means for producing periodic images when the detected changes of the sharpness and size signals indicate a decrease in both the sharpness and apparent size of the occupant.

11. The vehicle occupant sensor apparatus of claim 8 wherein the means for detecting changes determines that the occupant is positioned forward of the focal plane relative to the means for producing periodic images when the detected changes of the sharpness and size signals indicate one of the sharpness and apparent size of the occupant increasing and another of the sharpness and apparent size of the occupant decreasing.

12. A method of sensing a vehicle occupant comprising the steps of:

producing periodic images of an occupant, the periodic images having at least two focus attributes that are functionally related to a position of the occupant relative to a focal plane;

detecting changes in the at least two focus attributes of the periodic signals; and

determining the position of the occupant relative to the focal plane in response to the changes in the at least two focus attributes of the periodic signals.

13. The method of claim 12 further including the steps of:

receiving the periodic images in first and second filter means;

outputting sharpness signals that are indicative of a sharpness of the received periodic images from the first filter means; and

outputting size signals that are indicative of the apparent size of the occupant in the periodic images from the second filter means.

14. The method of claim 13 wherein the step of detecting changes in the focus attributes of the periodic signals includes the step of:

detecting changes in the sharpness and size signals.

15. The method of claim 14 wherein the step of determining the position of the occupant relative to the focal plane further includes the step of:

determining that the occupant is positioned rearward of the focal plane when the detected changes indicate an increase in both the sharpness and apparent size of the occupant.

16. The method of claim 14 wherein the step of determining the position of the occupant relative to the focal plane further includes the step of:

determining that the occupant is positioned rearward of the focal plane when the detected changes indicate a decrease in both the sharpness and apparent size of the occupant.

17. The method of claim 14 wherein the step of determining the position of the occupant relative to the focal plane further includes the step of:

determining that the occupant is positioned rearward of the focal plane when the detected changes indicate one of the sharpness and apparent size of the occupant increasing and another of the sharpness and apparent size of the occupant decreasing.