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

• US 20040210343A1
• Filed: 10/31/2003
• Published: 10/21/2004
• 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
• Granted Patent: US 7,171,285 B2
• Time in Patent Office: Days
• 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 using an image sensor, comprising:

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.

2. The mobile robot of claim 1, further comprising:

a memory for storing images outputted from the image capture unit; and

a comparator for comparing an image presently outputted from the image capture unit with a previous image stored in the memory.

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

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

5. The mobile robot of claim 1, wherein the image capture unit includes:

a luminous diode for irradiating light;

a light guide for guiding the irradiated light; and

an image sensor for capturing an image about the bottom surface by sensing intensity variation of light reflected onto the bottom surface through a light lens according to motion of the mobile robot.

6. A method for measuring a moving distance of a mobile robot by using an image sensor, comprising:

photographing the bottom surface according to motion of a mobile robot at a certain intervals and capturing an image;

measuring displacement between the captured images; and

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

7. The method of claim 6, further comprising:

storing the captured image.

8. The method of claim 6, wherein the image is divided into a certain pixels in the image capturing step, each pixel receives light reflected onto the bottom surface according to a material of the bottom surface and is discriminated by black and white brightness.

9. The method of claim 8, wherein the image is captured by 1500 frames per second so as to have 18*18 pixels and 64-degress brightness.

10. The method of claim 9, wherein the actual moving distance is calculated by dividing a pixel moving distance by a certain time, more preferable, {fraction (1/1500)} sec.

11. The method of claim 8, wherein a moving distance is measured according to direction of the pixel and magnitude of movement in the image in the displacement measuring step.

12. The method of claim 6, wherein it is judged the mobile robot is not moved, when each captured image is the same in comparison, it is judged the mobile robot is moved, when each captured image is not the same in comparison in the displacement measuring step.