Distance measurement apparatus for vehicle

• US 5,699,149 A
• Filed: 06/09/1995
• Issued: 12/16/1997
• Est. Priority Date: 06/09/1994
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ishii, Junichi, Komachiya, Masahiro, Kuroda, Hiroshi, Kanke, Atsushi
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US08/489,293
• Time in Patent Office: 921 Days
• Field of Search: 356/3.01, 356/3.06, 356/4.01, 356/5.01, 356/9, 348/135
• US Class Current: 356/4.01
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 17/931 of land vehicles

Abstract

The distance to a target object is measured by capturing the image in front of the driving vehicle using an image sensor, identifying a target object such as a vehicle ahead to which the distance is to be measured, and projecting a laser beam onto the target object. The distance to the target object is measured by angular surveying, using an image sensor for capturing an image as a laser light detection unit.

Claims

1. A distance measurement apparatus for a vehicle, comprising:

an image capturing apparatus for capturing an image of an area around a driving vehicle;

a signal processing unit for designating in said image a target vehicle to which a distance is to be measured;

a light emission unit for projecting a collimated laser beam onto said target vehicle; and

a distance unit for evaluating a distance by detecting a reflected laser beam from said target vehicle.

2. A method for measuring the distance of a target object from a vehicle, comprising:

a first step for selecting a target vehicle;

a second step for projecting a collimated laser beam onto a target vehicle; and

a third step for measuring the distance to said target vehicle by detecting a reflected laser beam from said target vehicle and evaluating the validity of a measured value of said distance;

wherein

if said measured value is valid, said second and third steps are repeated; and

otherwise, the first through the third steps are repeated.

3. A distance measuring apparatus for a vehicle, comprising:

an image capturing apparatus for capturing an image of an area around a driving vehicle;

a signal processing unit for designating in said image a target vehicle to which a distance is to be measured;

a light emission apparatus for projecting a collimated laser beam onto said target vehicle;

an image detecting apparatus having a light detection system for capturing light reflected from said target object and forming a target image thereof on said image detecting apparatus;

means for measuring the distance of said target image from a substantial center of said light detection system; and

means for measuring the distance to said target vehicle by using information concerning the position of said light emission apparatus, position of said light detection system, and said distance of said target image from said substantial center of said light detector system.

4. A distance measurement apparatus according to claim 3, wherein said light emission apparatus can change freely a direction in which a laser beam is emitted.

5. A distance measurement apparatus according to claim 3, further comprising:

means for changing intensity and phase of a laser beam by applying a designated modulation signal to said light emission apparatus;

means for processing image information captured by said image detecting apparatus in response to said modulation signal; and

means for distinguishing a reflected laser beam from background light.

7. A distance measurement apparatus according to claim 3 wherein a unit for emitting and detecting a laser beam has:

a support mechanism;

a sensor for detecting a vibration movement of a driving vehicle; and

an actuator for compensating said detected vibration movement.

8. A distance measurement apparatus according to claim 7 further comprising:

means for defining a marginal pixel region around a scanned pixel region in an image sensor of a light detection part, and for allowing said scanned pixel region to be moved freely in vertical and horizontal directions; and

an apparatus for detecting an image-blurring effect from image information captured on said scanned pixel region;

wherein

a control function is provided for shifting said scanned pixel region on said image sensor so as to compensate a vibration movement causing said image-blurring effect due to a vibration of a driving vehicle.

9. A distance measurement apparatus according to claim 8 further comprising:

a light detection unit having an auto-focus mechanism; and

means for focussing an image of a target vehicle on an image sensor.

10. A distance measurement apparatus according to claim 9 wherein said light detection unit further comprises:

an optical filter which passes light having a wave length identical to a light emitted from a light emission unit.

11. A distance measurement apparatus according to claim 10 wherein said image detecting apparatus detects light having a wave length identical to that of light emitted from said light emission apparatus.

6. A distance measurement apparatus for a vehicle comprising:

a light emission apparatus for emitting a laser beam with a variable emission range;

means for emitting a laser beam from said light emission apparatus in a wide range;

a signal processing part for detecting a reflected laser beam and for designating a target vehicle; and

a measurement apparatus for measuring the distance to said target vehicle by projecting a collimated laser beam onto said target vehicle from said light emission apparatus and detecting a reflected laser beam from said target vehicle.

12. A distance measurement apparatus for a vehicle, comprising:

a display unit for an image captured by a camera and presented to a vehicle driver; and

an input means on said display unit, allowing said vehicle driver to select a target vehicle to which a distance is measured by means of said image captured said camera;

wherein

said distance to said target vehicle is measured by projecting a collimated laser beam onto said target vehicle selected by said vehicle driver and detecting a reflected light from said target vehicle.