Inter-vehicle distance detecting device and inter-vehicle distance detecting method

• US 7,432,848 B2
• Filed: 11/22/2006
• Issued: 10/07/2008
• Est. Priority Date: 12/05/2005
• Status: Expired due to Fees

• Current Assignee: Alpine Electronics Incorporated (Alps Alpine Co., Ltd.)
• Original Assignee: Alpine Electronics Incorporated (Alps Alpine Co., Ltd.)
• Inventors: Munakata, Kohsuke
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): GALT, CASSI J
• Application Number:
  US11/562,873
• Publication Number:
  US 20070171121A1
• Time in Patent Office: 685 Days
• Field of Search: 342 70- 72, 382103-106, 701117-119, 701300-302
• US Class Current: 342/52
• CPC Class Codes: G01S 13/867 Combination of radar systems with cameras
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/9325 for inter-vehicle distance regulation, e.g. navigating in platoons
• CPC Class Codes: G01S 2013/93272 in the back of the vehicles
• CPC Class Codes: G06V 20/58 Recognition of moving objects or obstacles, e.g. vehicles or pedestrians; Recognition of traffic objects, e.g. traffic signs, traffic lights or roads
• CPC Class Codes: G06V 2201/08 Detecting or categorising vehicles

Abstract

There are provided an inter-vehicle distance detecting device and an inter-vehicle distance detecting method which can precisely measure an inter-vehicle distance from a user'"'"'s own vehicle to a neighboring vehicle even if a radar becomes unable to detect the neighboring vehicle due to the influence of multipath or the like. If the radar does detect a neighboring vehicle, a width of the neighboring vehicle is calculated based on a precise inter-vehicle distance determined by the radar and a precise vehicle visual angle determined from an image taken by a camera, and is stored in a memory, and if the radar becomes unable to detect the neighboring vehicle, an inter-vehicle distance to the neighboring vehicle is calculated according to a trigonometric function based on the precise width of the neighboring vehicle previously stored in the memory and a precise vehicle visual angle determined from an image taken by the camera at this time.

Claims

1. An inter-vehicle distance detecting device comprising:

a radar that detects a distance to a neighboring vehicle by measuring a period from emission of an electromagnetic wave to reception of the wave reflected by the neighboring vehicle;

a camera that images the neighboring vehicle;

an image processing unit that determines a visual angle of the neighboring vehicle as viewed from said camera by applying an image recognition process to an image acquired by said camera;

a width calculating unit that calculates the width of the neighboring vehicle based on the distance to the neighboring vehicle detected by said radar and the visual angle of the neighboring vehicle determined by said image processing unit;

a recording medium that stores information on the width of the neighboring vehicle calculated by said width calculating unit; and

a distance calculating unit that calculates the distance to the neighboring vehicle based on the information on the width of the neighboring vehicle stored in said recording medium and the visual angle of the neighboring vehicle determined by said image processing unit.

2. The inter-vehicle distance detecting device according to claim 1, comprising a control unit that causes said distance calculating unit to calculate the distance to the neighboring vehicle if said radar does not detect the neighboring vehicle.

3. The inter-vehicle distance detecting device according to claim 1, wherein said image processing unit determines a visual angle of an extent of the width of the neighboring vehicle.

4. The inter-vehicle distance detecting device according to claim 3, wherein said width calculating unit calculates the width W of the neighboring vehicle according to W=2L×

tan(θ

₁/2) wherein L denotes the distance to the neighboring vehicle detected by said radar, and θ

₁ denotes the visual angle of the extent of the width of the neighboring vehicle determined by said image processing unit.

5. The inter-vehicle distance detecting device according to claim 4, wherein said distance calculating unit calculates the distance X to the neighboring vehicle according to X=W/2tan(θ

₂/2) wherein θ

₂ denotes the visual angle of the extent of the width of the neighboring vehicle determined by said image processing unit.

6. The inter-vehicle distance detecting device according to claim 1, wherein said image processing unit determines a first visual angle of a range from a direction orthogonal to an image plane of said camera to one side of the width of the neighboring vehicle, and a second visual angle of a range from the direction orthogonal to the image plane of said camera to the other side of the width of the neighboring vehicle.

7. The inter-vehicle distance detecting device according to claim 6, wherein said width calculating unit calculates the width W of the neighboring vehicle according to W=L(cosθ

_3A×

tanθ

_3B−

sinθ

_3A), wherein L denotes the distance to the neighboring vehicle detected by said radar, and θ

_3A and θ

_3B respectively denote the first and second visual angles determined by said image processing unit.

8. The inter-vehicle distance detecting device according to claim 7, wherein said distance calculating unit calculates the distance X to the neighboring vehicle according to X=W/(cosθ

_4A×

tanθ

_4B−

sinθ

_4A), wherein θ

_4A and θ

_4B respectively denote the first and second visual angles determined by said image processing unit.

9. An inter-vehicle distance detecting method comprising:

a first act of determining whether a neighboring vehicle is detected by a radar based on a received signal strength of an electromagnetic wave received by the radar;

a second act of determining, upon a neighboring vehicle being detected by said first act, a distance to the neighboring vehicle based on a period from emission of the wave by the radar to reception of the wave reflected by the neighboring vehicle;

a third act of determining a visual angle of the neighboring vehicle as viewed from a camera by applying an image recognition process to an image acquired by the camera;

a fourth act of calculating the width of the neighboring vehicle based on the distance to the neighboring vehicle determined by said second act and the visual angle of the neighboring vehicle determined by said third act, and storing information on the acquired width in a recording medium;

a fifth act of, upon a neighboring vehicle not being detected by said first act, determining a visual angle of the neighboring vehicle as viewed from the camera by applying an image recognition process to the image acquired by the camera; and

a sixth act of calculating the distance to the neighboring vehicle based on the information on the width of the neighboring vehicle stored in the recording medium and the visual angle of the neighboring vehicle determined by said fifth act.

10. The inter-vehicle distance detecting method of claim 9, wherein the acts of determining a visual angle of the neighboring vehicle determine a visual angle of an extent of the width of the neighboring vehicle.

11. The inter-vehicle distance detecting method of claim 10, wherein the act of calculating the width calculates the width W of the neighboring vehicle according to W=2L×

tan(θ

₁/2) wherein L denotes the distance to the neighboring vehicle detected by said radar, and θ

₁ denotes the visual angle of the extent of the width of the neighboring vehicle.

12. The inter-vehicle distance detecting method of claim 11, wherein the act of calculating the distance calculates the distance X to the neighboring vehicle according to X=W/2tan(θ

₂/2) wherein θ

₂ denotes the visual angle of the extent of the width W of the neighboring vehicle.

13. The inter-vehicle distance detecting method of claim 9, wherein the acts of determining a visual angle of the neighboring vehicle determine a first visual angle of a range from a direction orthogonal to an image plane of said camera to one side of the width of the neighboring vehicle, and a second visual angle of a range from the direction orthogonal to the image plane of said camera to the other side of the width of the neighboring vehicle.

14. The inter-vehicle distance detecting method of claim 13, wherein the act of calculating the width calculates the width W of the neighboring vehicle according to W=L(cosθ

_3A×

tanθ

_3B−

sinθ

_3A), wherein L denotes the distance to the neighboring vehicle detected by said radar, and θ

_3A and θ

_3B respectively denote the first and second visual angles.

15. The inter-vehicle distance detecting method of claim 14, wherein the act of calculating the distance calculates the distance X to the neighboring vehicle according to X=W/(cosθ

_4A×

tanθ

_4B−

sinθ

_4A), wherein θ

_4A and θ

_4B respectively denote the first and second visual angles.

16. An inter-vehicle distance detecting method comprising:

storing a width of a neighboring vehicle;

determining a visual angle of the neighboring vehicle as viewed from a camera associated with the user'"'"'s own vehicle by applying an image recognition process to an image of the neighboring vehicle acquired by the camera; and

calculating the distance from the user'"'"'s own vehicle to the neighboring vehicle using the stored width and the visual angle of the neighboring vehicle.

17. The inter-vehicle distance detecting method of claim 16, wherein the width of the neighboring vehicle is calculated using a distance from the user'"'"'s own vehicle to the neighboring vehicle as determined by a radar associated with the user'"'"'s own vehicle, and a visual angle of the neighboring vehicle as viewed from the camera.

18. The inter-vehicle distance detecting method of claim 17, wherein the act of calculating the width calculates the width W of the neighboring vehicle according to W=2L×

tan(θ

₁/2) wherein L denotes the distance to the neighboring vehicle detected by said radar, and θ

₁ denotes the visual angle of the extent of the width of the neighboring vehicle.

19. The inter-vehicle distance detecting method of claim 16, wherein the act of calculating the distance calculates the distance X to the neighboring vehicle according to X=W/2tan(θ

₂/2) wherein θ

₂ denotes the visual angle of the extent of the width W of the neighboring vehicle.

20. The inter-vehicle distance detecting method of claim 16, wherein the act of determining a visual angle of the neighboring vehicle determines a first visual angle of a range from a direction orthogonal to an image plane of said camera to one side of the width of the neighboring vehicle, and a second visual angle of a range from the direction orthogonal to the image plane of said camera to the other side of the width of the neighboring vehicle.

21. The inter-vehicle distance detecting method of claim 20, further comprising an act of calculating the width which calculates the width W of the neighboring vehicle according to W=L(cosθ

_3A×

tanθ

_3B−

sinθ

_3A), wherein L denotes the distance to the neighboring vehicle detected by a radar, and θ

_3A and θ

_3B respectively denote the first and second visual angles.

22. The inter-vehicle distance detecting method of claim 21, wherein the act of calculating the distance calculates the distance X to the neighboring vehicle according to X=W/(cosθ

_4A×

tanθ

_4B−

sinθ

_4A), wherein θ

_4A and θ

_4B respectively denote the first and second visual angles.