Distance measuring apparatus and distance measuring method

• US 6,721,679 B2
• Filed: 10/26/2001
• Issued: 04/13/2004
• Est. Priority Date: 10/27/2000
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Aoyama, Chiaki
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Washburn, Douglas N
• Application Number:
  US09/984,040
• Publication Number:
  US 20020052711A1
• Time in Patent Office: 900 Days
• Field of Search: 356/3, 356/4.01, 702/158, 702/159, 354/3
• US Class Current: 702/158
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver

Abstract

A distance measuring apparatus is provided which utilizes a light-section method capable of measuring both close objects and far away objects without adjusting the dynamic range of an imaging camera. The apparatus comprises: an image acquisition section for imaging reflected light which has been emitted from the apparatus, has passed through a slit, and has then been reflected off the surface of a target object; an emission control section for controlling the emission time of the slit light during the time an image is being scanned by the image acquisition section, and for changing the intensity of the received light in the image acquisition section; and a distance calculation section for calculating the distance to the object based on the image taken by the image acquisition section and a positional relationship between a light emission position of the slit light and an image position.

Claims

1. A distance measuring apparatus comprising:

an image acquisition section for imaging reflected light which has been emitted from the apparatus, has passed through a slit, and has then been reflected off a surface of a target object to be measured;

an emission control section for controlling an emission time of the light which is emitted and passes through the slit during a time an image is being scanned by the image acquisition section, and for changing an intensity of the received light in the image acquisition section; and

a distance calculation section for calculating the distance to the object based on the image taken by the image acquisition section by referring to a positional relationship between a light emission position of the light passing through the slit and an image position.

2. The distance measuring apparatus according to claim 1, wherein the emission control section is constructed so as to determine the emission time according to the intensity of the reflected light received by the image acquisition section.

3. The distance measuring apparatus according to claim 1, wherein the image acquisition section removes pixels of a higher brightness than a predetermined first threshold value from the obtained images to generate images for a timing in which a relatively strong light is being projected, and removes pixels of a lower brightness than a predetermined second threshold value from the obtained images to generate images for a timing in which a relatively weak light is being projected.

4. A self-controlled robot incorporating the distance measuring apparatus according to claim 1.

5. The self-controlled robot according to claim 4, wherein the self-controlled robot is a bipedal robot.

6. The distance measuring apparatus according to claim 1, wherein the emission time is determined so that a brightness distribution of the reflected light is uniform based on the image taken by the image acquisition section.

7. The distance measuring apparatus according to claim 1, wherein the intensity of the received light is changed at a scanning period by changing the emission time in synchronization with a scanning period.

8. The distance measuring method comprising the steps of:

emitting light which has passed through a slit onto a target object to be measured;

imaging light reflected by the object by an imaging section;

based on the obtained image, measuring a distance to the object by referring to a positional relationship between a light emission position of the light which has passed through the slit and an image position; and

when the light passed through the slit is projected onto the object, varying an emission time of the light passed through the slit within a time period during which the imaging section scans the image.

9. The distance measuring method according to claim 8, wherein an intensity of the emitted light which passes through the slit and is projected onto the object is changed in accordance with the intensity of the imaged light reflected off the surface of the object.

10. The distance measuring method according to claim 8, wherein pixels of a higher brightness than a predetermined first threshold value are removed from the obtained images to generate images for a timing in which a relatively strong light is being projected;

pixels of a lower brightness than a predetermined second threshold value are removed from the obtained images to generates images for a timing in which a relatively weak light is being projected; and

the distance is measured based on the generated images.

11. The distance measuring method according to claim 8, wherein the emission time is determined so that a brightness distribution of the light reflected by the object is uniform based on the obtained image.

12. The distance measuring method according to claim 8, wherein the intensity of the light reflected by the object is changed at a scanning period by changing the emission time in synchronization with a scanning period.