Mobile robot using image sensor and method for measuring moving distance thereof

• US 7,171,285 B2
• Filed: 10/31/2003
• Issued: 01/30/2007
• Est. Priority Date: 04/03/2003
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Hong, Chan Hee, Kim, Se Wan
• Primary Examiner(s): Black; Thomas
• Assistant Examiner(s): Marc; McDieunel
• Application Number:
  US10/697,282
• Publication Number:
  US 20040210343A1
• Time in Patent Office: 1,187 Days
• Field of Search: 700/245
• US Class Current: 700/245
• CPC Class Codes: A47L 2201/04 Automatic control of the travelling movement; Automatic obstacle detection
• CPC Class Codes: G05D 1/0225 involving docking at a fixed facility, e.g. base station or loading bay parking aids B62D15/027
• CPC Class Codes: G05D 1/0253 extracting relative motion information from a plurality of images taken successively, e.g. visual odometry, optical flow determining position or orientation from images G06T7/70
• CPC Class Codes: G05D 1/0255 using acoustic signals, e.g. ultra-sonic singals sonar systems designed for anti-collision purposes G01S15/93
• CPC Class Codes: G05D 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51

Abstract

In a mobile robot and a method for measuring a moving distance thereof, by including an image capture unit for photographing the bottom surface according to motion of a mobile robot at a certain intervals and capturing images; a displacement measurer for measuring displacement about the captured image; and a microcomputer for outputting an actual moving distance by direction and motion of the mobile robot on the basis of the measured displacement value, it is possible to measure an accurate moving distance of the mobile robot with only one image sensor installed at the center of a body of the mobile robot, and accordingly it is possible to simplify a mechanical structure and facilitate maintenance and repairing.

Claims

1. A mobile robot comprising:

an image capturer that captures, at predetermined intervals, images of a bottom surface in accordance with motion of the mobile robot by using an image sensor;

a memory that stores images output from the image capturer;

a displacement measurer that measures displacement with respect to the captured image;

a comparator that compares an image presently output from the image capturer with an image previously stored in the memory; and

a microcomputer that outputs an actual moving distance by direction and motion of the mobile robot on the basis of a value of the measured displacement and a value of the compared images.

2. The mobile robot of claim 1, wherein the displacement measurer measures a moving path of pixels of an image of each frame output from the comparator.

3. The mobile robot of claim 1, wherein the image capturer captures an image of the bottom surface having 18*18 pixel and 64-degrees brightness by 1500 frames per second.

4. The mobile robot of claim 1, wherein the image capturer includes:

a luminous diode for irradiating light;

a light guide for guiding the irradiated light; and

an image sensor for capturing an image of the bottom surface by sensing an intensity variation of light reflected from the bottom surface through a lens in accordance with motion of the mobile robot.

5. A method for measuring a moving distance of a mobile robot comprising:

capturing, at predetermined intervals, an image of a bottom surface according to motion of a mobile robot by utilizing an image sensor;

storing images output from the image capturer in a memory;

measuring displacement between the captured two images by comparing an image presently output from the image capturer with an image previously stored in the memory; and

outputting an actual moving distance by calculating direction and motion of the mobile robot on the basis of a value of the measured displacement.

6. The method of claim 5, wherein the capturing comprises dividing the image into a predetermined number of pixels, each pixel receiving light reflected onto the bottom surface according to a material of the bottom surface and is discriminated by black and white brightness.

7. The method of claim 6, wherein the image is captured by 1500 frames per second so as to have 18*18 pixels and 64-degress brightness.

8. The method of claim 7, wherein the actual moving distance is calculated by dividing a pixel moving distance by a predetermined time of about 1/1500 sec.

9. The method of claim 6, wherein the displacement measuring comprises measuring a moving distance according to direction of the pixel and magnitude of movement in the image.

10. The method of claim 5, wherein, in the displacement measuring, when two captured images are the same, it is judged that the mobile robot is not moving, and when two captured images are not the same, it is judged that the mobile robot is moving.

11. The method of claim 5, wherein when two captured images are the same, the mobile robot is determined to not be moving and when two captured images are different, the mobile robot is determined to be moving.

12. A mobile robot comprising:

an image capturer that captures, at predetermined intervals, images of a predetermined surface based upon motion of the mobile robot, the mobile robot being configured for movement with respect to the predetermined surface;

a memory that stores images output from the image capturer;

a displacement measurer that measures displacement in accordance with the captured image;

a comparator that compares an image presently output from the image capturer with an image previously stored in the memory; and

a calculator that outputs a moving distance on the basis of a value of the measured displacement and a value of the compared images.

13. The mobile robot of claim 12, the image capturer including an image sensor.

14. The mobile robot of claim 12, wherein the image capturer comprises:

a luminous diode that radiates light;

a light guide that guides the light radiated by the luminous diode; and

an image sensor that captures an image of the predetermined surface by sensing an intensity variation of light reflected by the predetermined surface through a lens in accordance with a motion of the mobile robot.

15. The mobile robot of claim 12, wherein the displacement measurer is configured such that when each of two captured images are the same, it is determined that the mobile robot is not moving and when each of two captured images are not the same, it is determined that the mobile robot is moving.