Imaging system and method for fog detection

• US 9,514,373 B2
• Filed: 08/27/2014
• Issued: 12/06/2016
• Est. Priority Date: 08/28/2013
• Status: Active Grant

• Current Assignee: HL Klemove Corporation
• Original Assignee: Gentex Corporation
• Inventors: Jeromin, Oliver M., Falb, David M., Schut, Jeremy A.
• Primary Examiner(s): Chang, Daniel D
• Application Number:
  US14/469,899
• Publication Number:
  US 20150061493A1
• Time in Patent Office: 832 Days
• Field of Search: 315/82, 382/103, 382/104, 382/181
• US Class Current: 1/1
• CPC Class Codes: B60Q 1/143 combined with another condition, e.g. using vehicle recognition from camera images or activation of wipers
• CPC Class Codes: B60Q 1/20 Fog lights
• CPC Class Codes: B60Q 2300/312 Adverse weather
• CPC Class Codes: G06V 20/584 of vehicle lights or traffic lights

Abstract

An imaging system and method for fog detection are disclosed herein. An imager is configured to image a scene external and forward of a controlled vehicle and to generate image data corresponding to the acquired images. A controller is configured to receive and analyze the image data. When exterior lights of the controlled vehicle are operated in a low beam state, the controller is able to detect light sources of interest in the image data, determine if each light source of interest is a foggy light or a clear light, and generate a first signal if a fog entry condition is satisfied.

Claims

1. An imaging system for fog detection, comprising:

an imager configured to image a scene external and forward of a controlled vehicle and to generate image data corresponding to the acquired images; and

a controller for analyzing the image data and configured to;

detect light sources of interest in the image data;

determine if each light source of interest is a foggy light or a clear light;

count a number of foggy lights and clear lights; and

generate a first signal if a fog entry condition is satisfied, wherein satisfaction of the fog entry condition is based on a relationship between the number of foggy lights and the number of clear lights.

2. The imaging system of claim 1, wherein each light source of interest comprises one of a headlight, a taillight, and a streetlight, and wherein the controller is further configured to estimate a fog density based on one or more characteristics of at least one foggy light.

3. The imaging system of claim 1, wherein the imager comprises an image sensor with a plurality of pixels coupled to a colored filter for filtering red light received from each light source of interest, and wherein the controller determines whether each light source of interest is a foggy light or a clear light based on at least one of a number of pixels detecting red light and a measured red light intensity at each pixel.

4. The imaging system of claim 1, wherein the controller is further configured to generate a second signal if a fog exit condition is satisfied.

5. The imaging system of claim 4, wherein satisfaction of the fog exit condition is based on an expiration of a fog exit timer.

6. The imaging system of claim 4, wherein the first signal is used to at least one of place exterior lights of the controlled vehicle in a lower beam state and inhibit automatic high beam control of the exterior lights, and wherein the second signal is used to re-enable automatic high beam control of the exterior lights.

7. The imaging system of claim 1, wherein based on exterior lights of the controlled vehicle operating in a high beam state, the controller is further configured to detect backscatter to determine whether the fog entry condition is satisfied.

8. The imaging system of claim 1, wherein the fog entry condition is satisfied if at least one of a ratio and a difference between the number of foggy lights and the number of clear lights is greater than a threshold value.

9. A method of fog detection, comprising the steps of:

imaging a scene external and forward of the controlled vehicle and generating image data corresponding to the acquired images;

analyzing the image data to detect light sources of interest;

determining if each light source of interest is a foggy light or a clear light;

counting a number of foggy lights and clear lights; and

generating a first signal if a fog entry condition is satisfied, wherein satisfaction of the fog entry condition is based on a relationship between the number of foggy lights and the number of clear lights.

10. The method of claim 9, wherein the step of determining comprises filtering red light received from each light source of interest and sensing at least one of a light spread and an intensity associated with the red light.

11. The method of claim 9, further comprising the step of generating a second signal if a fog exit condition is satisfied, wherein the first signal is used to at least one of place exterior lights of the controlled vehicle in a lower beam state and inhibit automatic high beam control of the exterior lights, and wherein the second signal is used to re-enable automatic high beam control of the exterior lights.

12. The method of claim 9, further comprising the step of operating the exterior lights of the controlled vehicle in a high beam state and detecting backscatter to determine whether the fog entry condition is satisfied.

13. The method of claim 9, wherein each light source of interest comprises one of a headlight, a taillight, and a streetlight, and wherein the steps further comprise estimating a fog density based on one or more characteristics of at least one foggy light.

14. The method of claim 9, wherein the fog entry condition is satisfied if at least one of a ratio and a difference between the number of foggy lights and the number of clear lights is greater than a threshold value.

15. A non-transitory computer-readable medium having stored thereon software instructions that, when executed by a processor, comprise the steps of:

imaging a scene external and forward of the controlled vehicle and generating image data corresponding to the acquired images;

analyzing the image data to detect light sources of interest;

determining if each light source of interest is a foggy light or a clear light;

counting a number of foggy lights and clear lights; and

generating a first signal if a fog entry condition is satisfied, wherein satisfaction of the fog entry condition is based on a relationship between the number of foggy light and the number of clear lights.

16. The non-transitory computer-readable medium of claim 15, wherein the step of determining comprises filtering red light received from each light source of interest and sensing at least one of a light spread and an intensity associated with the red light.

17. The non-transitory computer-readable medium of claim 15, wherein the steps further comprise generating a second signal if a fog exit condition is satisfied, wherein the first signal is used to at least one of place exterior lights of the controlled vehicle in a lower beam state and inhibit automatic high beam control of the exterior lights, and wherein the second signal is used to re-enable automatic high beam control of the exterior lights.

18. The non-transitory computer-readable medium of claim 15, wherein the steps further comprise operating exterior lights of the controlled vehicle in a high beam state and detecting backscatter to determine whether the fog entry condition is satisfied.

19. The non-transitory computer-readable medium of claim 15, wherein each light source of interest comprises one of a headlight, a taillight, and a streetlight, and wherein the steps further comprise estimating a fog density based on one or more characteristics of at least one foggy light.

20. The non-transitory computer-readable medium of claim 15, wherein the fog entry condition is satisfied if at least one of a ratio and a difference between the number of foggy lights and the number of clear lights is greater than a threshold value.