Systems and methods for visual docking in an autonomous mobile robot

Patent metadata

Field	Value
Publication number	US-12096909-B2
Application number	US-202117363107-A
Country	US
Kind code	B2
Filing date	Jun 30, 2021
Priority date	Aug 14, 2020
Publication date	Sep 24, 2024
Grant date	Sep 24, 2024

Abstract

Systems, devices, and methods for docking a mobile robot to a dock using distinct visual fiducial markers on the dock are disclosed. A mobile robot system is provided that includes a dock and a mobile cleaning robot. The dock includes a first fiducial marker in a first plane on the dock and second one or more fiducial markers in a second plane different from the first plane. The mobile cleaning robot includes a visual system to detect the first and the second one or more fiducial markers, and a controller circuit to recognize the dock, and to determine a pose or heading direction of the mobile cleaning robot based on the detected first and the second one or more fiducial markers. The mobile drive system can adjust its heading direction, and drive to the dock according to the adjusted heading direction.

First claim

What is claimed is:

1. A mobile robot system, comprising:
a dock comprising: a first fiducial marker in a first plane; second one or more fiducial markers in a second plane different from the first plane; a docking platform; and a back plane behind the docking platform, wherein the first plane is parallel to the back plane with a first offset, and the second plane is parallel to the back plane with a second offset greater than the first offset; and
a mobile cleaning robot including:
a drive system configured to move the mobile cleaning robot about an environment including a docking area within a distance of the dock;
a visual system configured to detect the first fiducial marker and the second one or more fiducial markers on the dock; and
a controller circuit configured to:
recognize the dock based at least on the detected first fiducial marker;
determine a heading direction of the mobile cleaning robot with respect to the dock using the detected first fiducial marker and the detected second one or more fiducial markers; and
generate a control signal to the drive system to adjust the heading direction, and to drive the mobile cleaning robot to the dock in accordance with the adjusted heading direction.

2. The system of claim 1 , wherein the second plane is coplanar with the back plane.

3. The system of claim 1 , wherein the first fiducial marker includes a retroreflective artificial tag comprising a first area in a first color and a second area in a second color different from the first color, the first area having a higher retro-reflectance than the second area.

4. The system of claim 1 , wherein the second one or more fiducial markers are each laterally offset from the first fiducial marker.

5. The system of claim 1 , wherein the second one or more fiducial markers include a second fiducial marker laterally offset from the first fiducial marker in a first lateral direction, and a third fiducial marker laterally offset from the first fiducial marker in a second lateral direction opposite the first lateral direction.

6. A mobile robot system, comprising:
a dock comprising a first fiducial marker in a first plane, and second one or more fiducial markers in a second plane different from the first plane, wherein the second one or more fiducial markers are each disposed at, or in proximity to, respective one or more charging contacts on a docking platform of the dock, the one or more charging contacts electrically coupled to a charging system of the dock; and
a mobile cleaning robot including:
a drive system configured to move the mobile cleaning robot about an environment including a docking area within a distance of the dock;
a visual system configured to detect the first fiducial marker and the second one or more fiducial markers on the dock; and
a controller circuit configured to:
recognize the dock based at least on the detected first fiducial marker;
determine a heading direction of the mobile cleaning robot with respect to the dock using the detected first fiducial marker and the detected second one or more fiducial markers; and
generate a control signal to the drive system to adjust the heading direction, and to drive the mobile cleaning robot to the dock in accordance with the adjusted heading direction.

7. The system of claim 6 , wherein:
the mobile cleaning robot includes a light source configured to emit light; and
the second one or more fiducial markers each include respective retroreflective coatings attached to, or placed in proximity to, the respective one or more charging contacts, the retroreflective coatings configured to reflect the emitted light incident thereon back to the visual system of the mobile cleaning robot.

8. The system of claim 7 , wherein:
the one or more charging contacts include a first charging contact mounted over a base structure elevated above a horizontal surface of a charging platform of the dock, the first charging contact having a through-hole to expose a surface portion of the base structure behind the through-hole; and
the second one or more fiducial markers include a second fiducial marker comprising a retroreflective coating attached to the exposed surface portion behind the through-hole.

9. The system of claim 8 , wherein:
the through-hole of the first charging contact is sized and shaped to receive a raised portion of the base structure; and
the retroreflective coating of the second fiducial marker is attached to the raised portion of the base structure.

10. The system of claim 9 , wherein the raised portion of the base structure substantially flushes with an exterior surface of the charging contact abutting the through-hole.

11. The system of claim 1 , wherein the controller circuit is configured to:
determine the heading direction including determining an angle offset from normal to the back plane of the dock; and
generate the control signal to the drive system to adjust the heading direction of the mobile cleaning robot until the determined angle is within a specific angle range.

12. The system of claim 1 , wherein the visual system includes:
an imaging sensor configured to produce an image of the dock; and
an image processor configured to process the image, and to detect, from the processed image, respective positions of the first and the second one or more fiducial markers.

13. The system of claim 12 , wherein the controller circuit is configured to determine the heading direction using the detected positions of the second one or more fiducial markers relative to the detected position of the first fiducial marker.

14. The system of claim 13 , wherein the two of the more second fiducial markers include a second fiducial marker and a third fiducial marker, and the controller circuit is configured to:
measure, from the image of the dock, a first distance between the detected first fiducial marker and the detected second fiducial marker, and a second distance between the detected first fiducial marker and the detected third fiducial marker; and
determine the heading direction based on a comparison between the first distance and the second distance.

15. The system of claim 13 , wherein the controller circuit is configured to:
receive dock dimension information including actual positions of the second one or more fiducial markers relative to the first fiducial marker;
estimate positions of the second one or more fiducial markers using (1) the detected position of the first fiducial marker and (2) the actual positions of the second one or more fiducial markers relative to the first fiducial marker; and
determine the heading direction based on a comparison between the estimated positions of the second one or more fiducial markers and the detected positions of the second one or more fiducial markers.

16. The system of claim 13 , wherein the first fiducial marker includes a polygonal retroreflective artificial tag, and the controller circuit is configured to:
detect a position of at least one corner of the polygonal retroreflective artificial tag; and
determine the heading direction further using the detected position of the at least one corner of the polygonal retroreflective artificial tag.

17. The system of claim 1 , wherein the controller circuit is configured to:
determine the heading direction, including (1) determining a first heading direction using the detected first fiducial marker if the mobile cleaning robot is at a first distance away from the dock, and (2) determining a second heading direction using both the detected first fiducial marker and the detected second one or mo

Assignees

• Irobot Corp

Inventors

• Wong Cheuk Wah
• O'Brien John P
• Modh Milan

Classifications

• G05D1/244

  using passive navigation aids external to the vehicle, e.g. markers, reflectors or magnetic means · CPC title

• G05D1/661

  Docking at a base station (delivering or retrieving payloads G05D1/667) · CPC title

• A47L9/2857

  User input or output elements for control, e.g. buttons, switches or displays · CPC title

• A47L2201/04

  Automatic control of the travelling movement; Automatic obstacle detection · CPC title

• A47L2201/022

  Recharging of batteries · CPC title