WO2002022404A1

WO2002022404A1 - A camera arrangement

Info

Publication number: WO2002022404A1
Application number: PCT/SE2001/001964
Authority: WO
Inventors: Anders Olsson; Karl Munsin; Marcus Klomark
Original assignee: Autoliv Development Ab
Priority date: 2000-09-14
Filing date: 2001-09-14
Publication date: 2002-03-21
Also published as: GB2366862A; GB0022575D0; AU2001288165A1; GB2366862B

Abstract

A camera arrangement (1) for detecting an object on, above or in front of a vehicle seat, includes a camera (1) for creating an image of any object in that position, and also includes a wave source. In the preferred method of operational, an image is created with the wave source operation, and this image is stored in a store (11) and an image is taken with the source non-operational and this image is stored in a store (12). The images are then subtracted (13) to identify the image.

Description

"A CAMERA ARRANGEMENT"

THE PRESENT INVENTION relates to a camera arrangement and more particularly relates to a camera arrangement for use with a safety device, in particular in a motor vehicle.

In connection with the deployment of a safety device in a motor vehicle it is sometimes important to be able to detect and identify objects located in the region above and in front of a vehicle seat. For example, it may be necessary to determine the position of at least part of the occupant of the seat, for example the head of the occupant of the seat, so as to be able to determine the position of the occupant of the seat within the seat. If the occupant is leaning forwardly, for example, it may be desirable to modify the deployment of equipment in the vehicle, such as a safety device in the form of an airbag mounted directly in front of the occupant of the seat if an accident should occur. In the situation envisaged it may be appropriate only to inflate the airbag partially, rather than to inflate the airbag fully.

It could also be desirable to measure the height of the seat occupant, or the determine the position of the head of the occupant, especially the vertical distance between the seat and the head. If the front seat of a vehicle is not occupied by a person, but instead has a rear-facing child seat located on it, then it may be desirable to modify the deployment of an airbag located in front of that seat, in the event that an accident should occur, in such a way that the airbag does not inflate at all. If the airbag did inflate it might eject the child from the rear facing child seat.

Many prior proposals have been made concerning techniques that can be utilised to determine the position of part of an occupant of a seat and also to determine whether a seat is occupied by a rear-facing child seat. Some prior proposals have utilised optical techniques, and others have utilised techniques involving ultrasonic radiation or even "radar". In many prior arrangements the sensors have been mounted in front of the seat, and the signals derived from the sensors have been processed to calculate the distance between the occupant of the seat, or an item on the seat, and the sensors.

The present invention seeks to provide an improved camera arrangement which can be utilised to detect and evaluate objects on and above a vehicle seat.

According to this invention there is provided a camera arrangement for detecting an object on, above or in front of a vehicle seat, the arrangement comprising a wave source sending out a wave beam which is directed towards the space above and in front of said seat and a camera for creating an image of any object within the said space, wherein an image processor arrangement is provided to process an image created by the camera with the wave source operative and corresponding image created by the camera with the wave source interrupted to develop a resultant image, the resultant image comprising substantially only an image of any object or objects within said space. Preferably the processor of the image processor arrangement is adapted to subtract the second image from the first image.

Preferably the equipment is an airbag, headrest, pillar loop or seat belt pre-tensioner.

Conveniently the processor is configured to determine whether the seat is empty or whether it is occupied. The seat may be occupied by a person, or by a rear facing child seat.

Preferably the processor is configured to recognise, when the seat is occupied, predetermine objects or parts of objects and to determine the position thereof relative to the seat.

Advantageously the processor is configured to recognise the head of a human occupant of the seat and to determine the position thereof relative to the seat. Thus the processor may effectively determine the height of the occupant of the seat.

Conveniently the wave beam is a beam of light in the visible and/or non- visible part of the spectrum.

Preferably the electromagnetic wave beam consists solely of light in a non- visible part of the spectrum.

Conveniently the light beam is infra-red light.

Conveniently, in use, the position of an object shown in the resultant image is determined, and part of the second image at that position is added to the resultant image to provide an enhanced image. In an alternative arrangement it is a selected part of the first image that is added to the composite image to create the final image.

Preferably a single camera is used to create the first image and the second image.

Advantageously means are provided to time multiplex the creation of a plurality of said first and second images.

Conveniently the wave source and the camera are each located to one side of the seat, relative to the longitudinal axis of the vehicle.

Preferably the camera and the wave source are located close to the longitudinal centre line of the vehicle.

Conveniently the wave source generates a diverging beam.

This invention thus provides a camera arrangement, the camera arrangement comprising a camera having a predetermined field of view and a source generating a diverging beam of radiation, which may be electromagnetic radiation such as light, directed towards said field of view, means being provided to interrupt the radiation, means being provided to take successive images from the camera when the radiation is present and when the radiation is interrupted, means being provided to subtract an image from the camera when the radiation is interrupted from an image from the camera when the radiation is present to produce a resultant image. In order that the invention may be more readily understood, so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a diagrammatic top plan view of part of the cabin of a motor vehicle illustrating a camera arrangement in accordance with the invention illustrating a light source that forms part of the camera arrangement in the operative condition;

FIGURE 2 is a view corresponding to Figure 1 illustrating the light source in a non-operative condition;

FIGURE 3 is a schematic view of the image obtained from the camera arrangement with the light source in an operative condition;

FIGURE 4 is a schematic view corresponding to Figure 4 showing the image obtained when the light source is not operative;

FIGURE 5 is a view showing a resultant image obtained by subtracting the image of Figure 4 from the image of Figure 3; and

FIGURE 6 is a block diagram.

Referring initially to Figure 1, the camera arrangement of the present invention includes a camera 1. The camera 1 is responsive to a form of wave energy, such as light, and may be responsive to visible light, but is preferably also responsive to light outside the visible spectrum, such as infra-red light.

The camera may be solely responsive to light outside the visible spectrum. The camera may a conventional television camera or a charge-coupled- device, or CMOS camera or any other camera capable of capturing a "visible" image or wave energy image (which includes an image in the infra-red part of the spectrum) and converting that image to a corresponding electronic signal.

In the camera arrangement of Figure 1 the camera is associated with a source of a wave beam, which is preferably a diverging wave beam of electromagnetic energy, such as a light source 2. In the illustrated embodiment the light source 2 is an infra-red light source, that is to say a source of light which is in a non-visible part of the spectrum The light source generates diverging beam of light which is directed generally towards the field of view of the camera 1. The divergent light coming from the light source 2 is such that the illumination intensity of the resultant beam of light decreases with distance from the light source 2. The camera 1 is responsive to the light emitted by the light source.

In the embodiment of the invention illustrated in Figure 1 the camera 1 and the light source 2 are mounted in a motor vehicle, with the field of view of the camera 1 and the zone of illumination of the light source 2 being directed towards the area above a seat 3 of a motor vehicle. The seat 3 is shown, in Figure 1 occupied by an occupant 4.

It is envisaged that the camera and the infra-red light source will be mounted in a fixed position towards the centre of the vehicle, with the field of view of the camera and the zone of illumination of the light being directed, across the seat 3, towards the window or door adjacent the seat 3. Thus ordinarily only one occupant will be present within the field of view of the camera 1, or only one child seat n siicft a child seat is mounted oh the vehicle seat. The zone of light will also illuminate both an adult and a child if a child is seated on the lap of an adult occupant of the seat.

It is envisaged that the sensitivity of the camera 1 and the radiation intensity of the light source 2 will be so adjusted that the camera 1 is responsive to light reflected from the occupant 4 of the seat, but is not responsive (or is not so responsive) to light reflected from the parts of the cabin of the motor vehicle which are remote from the occupant 4, such as the door adjacent the occupant 4.

It is envisaged that the camera 1 will be utilised, in a first step, to capture an image with the light source 2 operational, as shown in Figure 1. In a subsequent step the camera captures an image with the light source non- operational, as shown in Figure 2.

Figure 3 illustrates schematically the image obtained in the first step, that is to say with the light source operational. Part of the image is the image of occupant, who is illuminated by the light source 2, and thus this part of the image is relatively bright. The rest of the image includes those parts of the cabin of the vehicle detected by the camera 1 and also part of the image entering the vehicle through the window.

Figure 4 illustrates the corresponding image taken with the light source 2 non-operational. The occupant 4 of the vehicle is not so bright, in this image, since the occupant is not illuminated by the light source 2, but the rest of the image is virtually the same as the image of Figure 3.

Successive signals from the camera 1 are passed to an image processor ιυ¹ wnere signals representing trie first image,^' with¹ illumination, are stored in a store 11, and signals representing the second image, without illumination, are stored in a store 12. The two signals are subtracted in the subtractor 13. Thus, effectively the second image, without illumination is subtracted, pixel-by-pixel, from the first image as shown in Figure 3, taken with the light source 2 operative. The resultant image, as shown in Figure 5, consists substantially of an image of only the occupant of the vehicle, that is to say only that part of the field of view of the camera 1 illuminated by light from the light source 2. Signals representing this image are passed to a processor 14.

The processor 14 will process the image to determine whether the seat is completely empty or is occupied in any way. The processor is configured to identify and recognise predetermined objects, such as child seats, or parts of objects, such as the head of a human occupant of the seat, and to determine the position thereof relative to the seat. Thus the processor will process the image by determining the nature of the image, for example by determining whether the image is an image of an occupant of a seat or an image of a rear-facing child seat, and will determine the position of part of or the whole of the image.

In one embodiment of the invention, when the position of the object or part of the object has been determined, part of second image, that is the image without illumination, at the position occupied by the object, is added to the resultant image to provide an enhanced image. The enhanced image may be used to provide a more accurate assessment of the position of the object.

The taking of successive images and the subtraction of signals representing the images and the processing step is repeated continuously, in a time multiplex manner. If the image is an image of a rear-facing child seat the processor may, through a control arrangement 15, inhibit deployment of a safety device in the form of an airbag mounted in the dashboard in front of the seat.

If the processor 14 determines that the image is an image of an occupant the processor will then determine if part of the occupant such as the head of the occupant, is in a predetermined part of the image. Because the field of view of the camera is fixed in position it is possible to determine the position in the vehicle of part of the occupant by determining the position of that part of the occupant within the image. It is thus possible to calculate the distance between part of the occupant, such as the head of the occupant and the dashboard or steering wheel to determine if the occupant is "in position" or "out of position". If the occupant is "out of position" the deployment of an airbag in front of the occupant may be modified by the control arrangement 15. The image processor 14 may also be adapted to determine the size of the image. Thus the processor will discriminate between a small seat occupant, such as a child, or a large seat occupant, such an obese adult. The processor 14 may also determine the position of the head of the occupant above the seat, thus effectively determining a parameter related to the height of the occupant. The processor 14 may also be adapted to determine if the image is actually an image of a child seated on the lap of an adult seat occupant. In dependence upon the determination, the manner of deployment of an airbag provided to protect the occupant of the seat may be modified ,or even inhibited, by the control arrangement 15.

It is to be appreciated that the camera arrangement as described above, will be sequentially operated with the light 2 on and with the light 2 off, with a subsequent subtraction of the detected images. Alternative mechanisms, such as a shutter, may be used to interrupt the beam of light. If an infra-red light is used, the light will not be in any way visible to the driver or occupant of the vehicle and will thus not distract the driver or occupant of the vehicle, especially after dark. It is for this reason that it is preferred to use a light source that is not within the visible spectrum.

Whilst the invention has been described with reference to the modification of deployment of a safety device such as an airbag it is to be appreciated that the safety device whose deployment is modified may comprise alternative forms of safety device such as a pre-tensioner adapted to pre-tension a safety belt, a pillar loop, or an headrest on a seat.

In the present Specification "comprise" means "includes or consists of and "comprising" means "including or consisting of.

Claims

CLAIMS:

1. A camera arrangement for detecting an object on, above or in front of a vehicle seat, the arrangement comprising a wave source sending out a wave beam which is directed towards the space above and in front of said seat and a camera for creating an image of any object within the said space, wherein an image processor arrangement is provided to process an image created by the camera with the wave source operative and corresponding image created by the camera with the wave source interrupted to develop a resultant image, the resultant image comprising substantially only an image of any object or objects within said space.

2. A camera arrangement according to Claim 1 wherein the processor of the image processor arrangement is adapted to subtract the second image from the first image.

3. An arrangement according to Claim 2 wherein the processor is configured to determine whether the seat is empty or whether it is occupied.

4. An arrangement according to Claim 3 wherein the processor is configured to recognise, when the seat is occupied, predetermine objects or parts of objects and to determine the position thereof relative to the seat.

5. An arrangement according to Claim 5 wherein the processor is configured to recognise the head of a human occupant of the seat and to determine the position thereof relative to the seat.

6. An arrangement according to any one of Claims 2 to 5 wherein the processor controls or modifies the operation of equipment in the vehicle.

7. An arrangement according to Claim 6 wherein the equipment is an airbag, headrest, pillar loop or seat belt pre-tensioner.

8. A camera arrangement according any one of the preceding Claims wherein the wave beam is a beam of light in the visible and/or non- visible part of the spectrum.

9. An arrangement according to any one of the preceding Claims wherein the wave beam consists solely of light in a non- visible part of the spectrum.

10. An arrangement according to Claim 9 wherein the light beam is infra-red light.

11. An arrangement according to any one of the preceding Claims wherein, in use, the position of an object shown in the resultant image is determined, and part of the second image at that position is added to the resultant image to provide an enhanced image.

12. A camera arrangement according to any one of the preceding Claims wherein a single camera is used to create the first image and the second image.

13. An arrangement according to any one of the preceding Claims wherein means are provided to time multiplex the creation of a plurality of said first and second images.

14. An arrangement according to any one of the preceding Claims wherein the wave source and the camera are each located to one side of the seat, relative to the longitudinal axis of the vehicle.

15. An arrangement according to Claim 14 wherein the camera and the wave source are located close to the longitudinal centre line of the vehicle.

16. An arrangement according to any one of the preceding Claims wherein the wave source generates a diverging beam.