Vehicle speed determination via infrared imaging

• US 8,935,082 B2
• Filed: 01/24/2012
• Issued: 01/13/2015
• Est. Priority Date: 01/24/2012
• Status: Active Grant

• Current Assignee: Conduent Business Services, LLC (Conduent, Inc.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Wu, Wencheng, Dalal, Edul N
• Primary Examiner(s): Algahaim, Helal A
• Assistant Examiner(s): CASTRO, PAUL A
• Application Number:
  US13/357,034
• Publication Number:
  US 20130191014A1
• Time in Patent Office: 1,085 Days
• Field of Search: 701/117, 701/119, 382/106
• US Class Current: 701/119
• CPC Class Codes: G08G 1/0116 from roadside infrastructure, e.g. beacons
• CPC Class Codes: G08G 1/052 with provision for determining speed or overspeed speed measuring in general G01P
• CPC Class Codes: G08G 1/054 photographing overspeeding vehicles

Abstract

A system and method which detects and uses a point of contact between a vehicle'"'"'s tire and the pavement as a reference point to improve the accuracy of vehicle speed detection in a motorized vehicle speed detection system. In one embodiment, a plurality of infrared images of a moving vehicle are received. Each of the images is separated in time by known intervals. The images are captured using an infrared camera which can be a single-band or multi-band camera which operates in an infrared wavelength band selected to enhance a contrast between the vehicle'"'"'s tires and the road surface. For each image, a point of contact is determined where a same tire contacts the road surface. These points and the time interval separations are used to calculate the vehicle'"'"'s speed. An alert signal is initiated to a traffic enforcement authority if the speed exceeds the road'"'"'s speed limit.

Claims

1. A method for reducing speed error in determining the speed of a motor vehicle in a vehicle speed detection system, the method comprising:

receiving a plurality of infrared images of a motor vehicle traveling on a road, each of said images being separated in time by a known interval, said infrared images having been captured using a single camera infrared imaging system operating in an infrared wavelength band spectrum range specifically selected such that a contrast of a point of contact between the tires of said vehicle and the road surface is optimized with respect to road material and tire rubber in said images, said infrared imaging system positioned adjacent the road;

determining, for each of at least two of said images, the point of contact where a same tire of said vehicle contacts said road surface, such that a height of each point of contact is zero;

mapping said points of contact to a (x,y) two dimensional coordinate system, such that each point of contact has a (x,y) set of coordinates;

using said coordinates and said time interval separations to calculate a speed at which said vehicle is traveling on said road; and

communicating said vehicle'"'"'s speed to a computer system;

for comparing said vehicle'"'"'s speed to a speed limit established for said road.

2. The method of claim 1, wherein said infrared imaging system comprises any of a single-band and a multi-band infrared camera.

3. The method of claim 1, wherein said infrared wavelength band includes a portion of the electromagnetic spectrum between 0.7 μ

m and 9.7 μ

m in wavelength.

4. The method of claim 1, wherein said images comprise any of:

still images captured at known time intervals, and video images captured at a known frame rate.

5. The method of claim 1, wherein said road surface comprises any combination of:

asphalt, concrete, metal, and gravel.

6. The method of claim 1, further comprising calibrating said infrared camera such that pixel locations of said captured images are known relative to real world coordinates.

7. The method of claim 1, further comprising:

analyzing more than two images of said vehicle using contact points determined for each of a plurality of images over a plurality of time intervals; and

determining at least one of a mean speed, a median speed, a maximum speed and a minimum speed, for said vehicle from said analysis of more than two images.

8. The method of claim 1, further comprising determining a time-varying speed for said vehicle using at least some of said images.

9. The method of claim 1, further comprising initiating an alert signal in response to said vehicle'"'"'s speed exceeding said speed limit.

14. The system of claim 1, wherein said road surface comprises any combination of asphalt, concrete, metal, and gravel.

10. A system for reducing speed error in determining the speed of a motor vehicle in a vehicle speed detection system, the system comprising:

a single camera infrared imaging system operating in an infrared wavelength band spectrum range specifically selected such that a contrast of a point of contact between tires of said vehicle and a road surface is optimized with respect to road material and tire rubber in said images, said infrared imaging system positioned a processor in communication with said video camera system and a memory, said processor executing machine readable instructions for performing;

receiving infrared images captured using said infrared imaging system, each of said infrared images being separated in time by a known interval;

determining, for each of at least two of said images, the point of contact where a same tire of said vehicle contacts said road surface, such that a height of each point of contact is zero;

mapping said points of contact to a (x,y) two dimensional coordinate system, such that each point of contact has a set of (x,y) coordinates;

using said coordinates and said time interval separations to calculate a speed at which said vehicle is traveling on said road; and

communicating said vehicle'"'"'s speed to a computer system;

for comparing said vehicle'"'"'s speed to a speed limit established for said road.

11. The system of claim 10, wherein said infrared imaging system comprises any of a single-band and a multi-band infrared camera.

12. The system of claim 10, wherein said infrared wavelength band includes a portion of the electromagnetic spectrum between 0.7 μ

m and 9.7 μ

m in wavelength.

13. The system of claim 10, wherein said images comprise any of still images captured at known time intervals, and video images captured at a known frame rate.

15. The system of claim 10, further comprising calibrating said infrared camera such that pixel locations of said captured images are known relative to real world coordinates.

16. The system of claim 10, further comprising:

analyzing more than two images of said vehicle using contact points determined for each of a plurality of images over a plurality of time intervals;

and determining at least one of a mean speed, a median speed, a maximum speed and a minimum speed, for said vehicle from said analysis of more than two images.

17. The system of claim 10, further comprising determining a time-varying speed for said vehicle using at least some of said images.

18. The system of claim 10, further comprising initiating an alert signal in response to said vehicle'"'"'s speed exceeding said speed limit.

19. A computer implemented method for reducing speed error in determining the speed of a motor vehicle in a vehicle speed detection system, the method comprising:

receiving a plurality of infrared images of a moving vehicle, said images captured at known time intervals with each of said images being separated in time by a known interval, said images having been captured using a single camera infrared imaging system operating in an infrared wavelength band spectrum range specifically selected such that a contrast of a point of contact between the tires of said vehicle and the road surface is optimized with respect to road material and tire rubber in said images, said infrared imaging system positioned adjacent the road;

determining, for each of at least two of said images, the point of contact where a same tire of said vehicle contacts said road surface, such that a height of each point of contact is zero;

mapping said points of contact to a (x,y) two dimensional coordinate system, such that each point of contact has a (x,y) set of coordinates;

using said coordinates and said time interval separations to calculate a speed at which said vehicle is traveling on said road; and

communicating said vehicle'"'"'s speed to a computer system;

for comparing said vehicle'"'"'s speed to a speed limit established for said road.

20. The computer implemented method of claim 19, further comprising calibrating said infrared camera such that pixel locations of said captured images are known relative to real world coordinates.

21. The computer implemented method of claim 19, further comprising:

calculating a plurality of speeds for said vehicle using contact points determined for each of a plurality of images over a plurality of time intervals;

and determining an average speed for said vehicle from said plurality of speeds.

22. The computer implemented method of claim 19, further comprising determining a time-varying speed for said vehicle using at least a portion of said plurality of images.