Mobile robot and method for controlling and detecting inclination using pattern light

• US 10,656,656 B2
• Filed: 05/17/2017
• Issued: 05/19/2020
• Est. Priority Date: 05/17/2016
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Jun, Woochan, Sung, Chulmo
• Primary Examiner(s): Nolan, Peter D
• Assistant Examiner(s): Thomas, Ana D
• Application Number:
  US15/597,670
• Publication Number:
  US 20170336796A1
• Time in Patent Office: 1,098 Days
• CPC Class Codes: A47L 2201/022 Recharging of batteries
• CPC Class Codes: A47L 2201/04 Automatic control of the travelling movement; Automatic obstacle detection
• CPC Class Codes: A47L 5/22 with rotary fans
• CPC Class Codes: A47L 9/009 Carrying-vehicles; Arrangements of trollies or wheels; Means for avoiding mechanical obstacles
• CPC Class Codes: A47L 9/0472 Discs
• CPC Class Codes: A47L 9/0477 Rolls
• CPC Class Codes: A47L 9/0488 Combinations or arrangements of several tools, e.g. edge cleaning tools
• CPC Class Codes: A47L 9/2826 the condition of the floor
• CPC Class Codes: A47L 9/2852 Elements for displacement of the vacuum cleaner or the accessories therefor, e.g. wheels, casters or nozzles
• CPC Class Codes: A47L 9/2873 Docking units or charging stations for autonomous or robotic vacuum cleaners A47L2201/02
• CPC Class Codes: G05D 1/0214 in accordance with safety or protection criteria, e.g. avoiding hazardous areas monitoring the location of vehicles within a certain area, e.g. forbidden or allowed areas, in traffic control systems for road vehicles G08G1/13
• CPC Class Codes: G05D 1/0246 using a video camera in combination with image processing means
• CPC Class Codes: G05D 1/0248 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/027 comprising intertial navigation means, e.g. azimuth detector inertial navigation G01C21/16; inertial navigation combined with non-inertial navigation instruments G01C21/165

Abstract

A mobile robot of the present disclosure emits a first patterned light downward and forward from a main body on a floor of an area to be cleaned and a second patterned light upward and forward from the main body, determines an obstacle based on an image of each emitted patterned light which is incident on the obstacle, and senses a tilt of the main body to compensate for the tilt. In this manner, an obstacle may be determined accurately, and after the tilt compensation, redetermination is made as to whether it is possible to pass through, so as to enable the mobile robot to pass through or bypass the obstacle. Accordingly, the mobile robot may reach a wider area to be cleaned, thereby extending the area that may be cleaned, and enabling fast determination and operation for effective traveling, such that the mobile robot may escape from an obstacle without being limited thereby.

Claims

1. A mobile robot, comprising:

a main body configured to travel in an area to be cleaned and apply suction to a floor in the area;

a sensor configured to detect a tilt of the main body;

a first pattern light source provided on a front portion of the main body and configured to emit a first patterned light toward a first sub-area of a particular area;

an camera provided on the front portion of the main body and configured to capture an image of the particular area; and

a controller configured to;

detect a first optical pattern, corresponding to the first patterned light, in the image captured from the camera,

perform tilt compensation relative to the first optical pattern based on the tilt of the main body,

determine whether an obstacle is present in the particular area based on the tilt-compensation and first optical pattern, and

control a movement of the main body based on whether the obstacle is present,

wherein the controller is further configured to;

determine, based on the tilt of the main body, whether the obstacle includes a slope,

determine an inclination angle of the slope, and

when the inclination angle of the slope is equal to or less than a predetermined angle, control the main body to move up the slope.

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

a second pattern light source provided below the first pattern light source on the front portion of the main body and configured to emit a second patterned light toward a second sub-area of the particular area, the second sub-area being position above the first sub-area,

wherein the controller is further configured to;

detect second optical pattern, corresponding to the second patterned light, in the image captured from the camera, and

determine whether an obstacle is present in the particular area further based on the second optical pattern.

3. The mobile robot of claim 1, wherein the controller, when performing the tilt compensation, is further configured to:

adjust a position of the first optical pattern in the image based on the tilt of the main body.

4. The mobile robot of claim 3, wherein the controller, when adjusting the position of the first optical pattern in the image based on the tilt of the main body, is further configured to:

raise the first optical pattern in the image when the tilt of the main body indicates that the front portion of the main body is positioned higher than a rear portion of the main body, and

lower the first optical pattern in the image when the tilt of the main body indicates that the front portion of the main body is positioned lower than the rear portion of the main body.

5. The mobile robot of claim 3, wherein the controller, when adjusting the position of the first optical pattern in the image based on the tilt of the main body, is further configured to:

adjust a slope of the first optical pattern in the image based on the tilt of the main body when the tilt indicates that main body is inclined left or right.

6. The mobile robot of claim 1, wherein the controller, when determining whether the obstacle is present in the particular area, is further configured to compare a position of the first optical pattern in the image with a reference position, and determine that the obstacle is present in the particular area when the first optical pattern is positioned in the image above the reference position, and

wherein the controller, when compensating for the tilt, is further configured to:

change the reference position in the image according to the tilt of the main body.

7. The mobile robot of claim 6, wherein the controller, when determining whether the obstacle is present in the particular area, is further configured to:

determine that no obstacle is present in the particular area when the first optical pattern is positioned in the image are the adjusted reference position; and

determine that there an obstacle is present in the particular region when the first optical pattern is positioned in the image above the adjusted reference position.

8. The mobile robot of claim 6, wherein the controller, when changing the reference position in the image according to the tilt of the main body, is further configured to:

lower the reference position when the tilt of the main body indicates that the front portion of the main body is positioned higher than a rear portion of the main body, and

raise the reference position when the tilt of the main body indicates that the front portion of the main body is positioned lower than the rear portion of the main body.

9. The mobile robot of claim 1, wherein the controller, when determining whether the obstacle is present in the particular area based on the tilt-compensation and first optical pattern, is further configured to:

when a tilt angle of the main body is equal to or less than a threshold angle, determine whether the obstacle is present in the particular area based on the tilt compensated first optical pattern; and

when the tilt angle of the main body is greater than the threshold angle, determine that the obstacle is not present in the particular area.

10. The mobile robot of claim 9, wherein the controller, when controlling the movement of the main body, is further configured to:

when the tilt angle of the main body is greater than the threshold angle, direct the main body to move forward through particular area.

11. The mobile robot of claim 1, wherein the sensor comprises at least one inclination sensor to measure a tilt direction and a tilt angle of a portion of the main body.

12. The mobile robot of claim 11, wherein the inclination sensor comprises at least one of a tilt sensor or an acceleration sensor.

13. The mobile robot of claim 1, wherein the controller is further configured to:

when the inclination angle of the slope is equal to or less than the predetermined angle, perform the tilt compensation according to the inclination angle; and

when the inclination angle of the slope is greater than the predetermined angle, control the main body to bypass the slope.

14. The mobile robot of claim 1, wherein the first optical pattern includes a horizontal portion, and the controller, when compensating for the tilt is further configured to:

perform tilt compensation relative to the horizontal portion based on the tilt of the main body.

15. The mobile robot of claim 1, wherein the controller is further configured to determine that the obstacle is a cliff and to direct the main body to travel in a path to avoid the cliff.

16. The mobile robot of claim 1, wherein the controller is further configured to change a direction travelled by the main body when a tilt angle of the main body is greater than a threshold angle.

17. The mobile robot of claim 1, wherein the controller is further configured to determine that the main body is passing over the obstacle when a tilt angle of the main body changes from a first value to a second value over a threshold distance.

18. The mobile robot of claim 17, wherein the controller is further configured to:

direct the main body to continue over the obstacle when the tilt angle of the main body is equal to or less than a threshold value, and

direct the main body to reverse when the tilt angle of the main body is above the threshold value.

19. The mobile robot of claim 1, wherein the controller is further configured to determine that the obstacle includes a slope and to direct the main body to travel in a path through the slope when an inclination of the slope is less than a threshold angle.

20. The mobile robot of claim 1, wherein the controller, when performing the tilt compensation, is further configured to:

adjust a position of the first optical pattern based on the inclination angle of the slope.