Robotic lawn mowing boundary determination

• US 9,516,806 B2
• Filed: 10/10/2014
• Issued: 12/13/2016
• Est. Priority Date: 10/10/2014
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Yamauchi, Brian, Beaulieu, Andrew, Balutis, Paul
• Primary Examiner(s): CAMBY, RICHARD M
• Application Number:
  US14/512,098
• Publication Number:
  US 20160100522A1
• Time in Patent Office: 795 Days
• Field of Search: 701/25
• US Class Current: 1/1
• CPC Class Codes: A01B 69/008 automatic
• CPC Class Codes: A01D 2101/00 Lawn-mowers
• CPC Class Codes: A01D 34/008 for automated or remotely controlled operation
• CPC Class Codes: G05D 1/0212 with means for defining a desired trajectory involving a plurality of land vehicles G05D1/0287
• CPC Class Codes: G05D 1/0219 ensuring the processing of the whole working surface
• CPC Class Codes: G05D 1/0221 involving a learning process
• CPC Class Codes: G05D 1/0236 in combination with a laser lasers per se H01S
• CPC Class Codes: Y10S 901/01 Mobile robot

Abstract

A method of mowing an area with an autonomous mowing robot comprises storing, in non-transient memory of the robot, a set of geospatially referenced perimeter data corresponding to positions of the mowing robot as the mowing robot is guided about a perimeter of an area to be mowed, removing from the set of perimeter data one or more data points thereby creating a redacted data set and controlling the mowing robot to autonomously mow an area bounded by a boundary corresponding to the redacted data set, including altering direction of the mowing robot at or near a position corresponding to data in the redacted data set so as to redirect the robot back into the bounded area.

Claims

1. A method of mowing an area with an autonomous mowing robot, the method comprising:

storing, in non-transient memory of the robot, a set of geospatially referenced perimeter data corresponding to positions of the mowing robot as the mowing robot is guided about a perimeter of an area to be mowed;

comparing, via a controller communicably coupled to the non-transient memory of the robot, at least two adjacent data points from the set of geospatially referenced perimeter data to determine which point corresponds to a position that is adjacent both mowable and unmowable portions and that is directly adjacent other points separating mowable and unmowable portions;

removing, via the controller, one or more of the at least two adjacent data points from the set of perimeter data, thereby creating a redacted data set; and

controlling the mowing robot to autonomously mow an area bounded by a boundary corresponding to the redacted data set, including altering direction of the mowing robot at or near a position corresponding to data in the redacted data set so as to redirect the robot back into the bounded area.

2. The method of claim 1, further comprising, prior to storing the geospatially referenced data, determining locations of discrete markers along the perimeter of the area to be mowed.

3. The method of claim 2, wherein the geospatially referenced data are geospatially referenced as the mowing robot is guided about the perimeter in relation to the discrete markers.

4. The method of claim 1, further comprising, prior to removing data points from the set of perimeter data, determining a reference point from a location of the mowing robot within the area to be mowed and determining which point of the at least two adjacent data points corresponds to a position that is furthest from the reference point.

5. The method of claim 4, comprising prompting an operator to position the mowing robot within the area to be mowed and to then initiate a reference point determination.

6. The method of claim 4, wherein whether the boundary corresponding to the redacted data set is an interior boundary or an exterior boundary of the area to be mowed is determined from the location of the reference point with respect to the boundary.

7. The method of claim 1, wherein storing the geospatially referenced perimeter data comprises marking cells of a two-dimensional data array as corresponding to the positions of the mowing robot.

8. The method of claim 7, wherein removing the one or more data points comprises altering entries in one or more marked cells to indicate that such cells do not correspond to perimeter locations.

9. The method of claim 8, wherein the data points to be removed are BOUNDARY cells that are not adjacent to both MOWABLE and NON-MOWABLE cells.

10. The method of claim 1, wherein storing the set of perimeter data comprises determining whether the mowing robot is being guided in a forward or a backward direction, and pausing data storage while the mowing robot is being guided in the backward direction.

11. The method of claim 1, further comprising, prior to controlling the robot to autonomously mow the area, determining whether the stored perimeter data represents a continuous path.

12. The method of claim 11, further comprising adding data points to fill any path gaps of less than a predetermined width.

13. The method of claim 11, further comprising, upon determining that the stored perimeter data represents a discontinuous path defining a gap of more than a predetermined width, signaling an operator to resume guidance of the mowing robot about the perimeter and storing additional perimeter data during resumed guidance.

14. The method of claim 1, further comprising, prior to controlling the robot to autonomously mow the area, altering a portion of the stored perimeter data set corresponding to a perimeter path segment defining an interior angle less than 135 degrees, to define a smoothed boundary.

15. The method of claim 1, wherein the storage of the set of perimeter data is paused while the guided mowing robot remains stationary for less than a predetermined time interval, and resumes upon motion of the mowing robot.

16. The method of claim 15, wherein the storage of the set of perimeter data is concluded in response to the guided mowing robot remaining stationary for more than the predetermined time interval.

17. The method of claim 1, wherein controlling the mowing robot to autonomously mow the area comprises determining whether the mowing robot is within a predetermined distance from the boundary, and in response to determining that the mowing robot is within the predetermined distance, slowing a mowing speed of the robot.

18. The method of claim 1, wherein the perimeter is an external perimeter circumscribing the area to be mowed.

19. The method of claim 1, wherein the perimeter is an internal boundary circumscribing an area surrounded by the area to be mowed.

20. An autonomous mowing robot comprising:

a robot body carrying a grass cutter;

a drive system including a motorized wheel supporting the robot body;

a controller operably coupled to the motorized wheel for maneuvering the mowing robot to traverse a bounded lawn area while cutting grass, the controller configured to;

in a teaching mode, store in non-transient memory a set of geospatially referenced boundary data corresponding to positions of the mowing robot as the mowing robot is guided about a border of the bounded lawn area;

in the teaching mode, store reference data corresponding to a reference position within the bounded lawn area;

compare at least two adjacent data points from the set of geospatially referenced boundary data to determine which point corresponds to a position that is furthest from the reference position of the bounded lawn area;

remove from the set of boundary data one or more of the at least two adjacent data points corresponding to positions spatially closer to the reference position than another adjacent position represented by another data point of the set of boundary data, thereby creating a redacted boundary data set; and

then,

in an autonomous operating mode, control the mowing robot to autonomously mow an area bounded by a path corresponding to the redacted boundary data set, including altering direction of the mowing robot at or near a position corresponding to data in the redacted data set so as to redirect the robot back into the bounded area.

21. The autonomous mowing robot of claim 20, further comprising an emitter/receiver carried on the robot body and configured to communicate with perimeter markers bounding the bounded lawn area in the teaching mode.

22. The autonomous mowing robot of claim 20, further comprising a removable handle securable to the robot body and graspable by an operator to manually guide the mowing robot about the border of the bounded lawn area in the teaching mode.

23. The autonomous mowing robot of claim 22, wherein the robot is configured to detect if the handle is attached to the robot body.

24. The autonomous mowing robot of claim 22, wherein the controller is configured to initiate the teaching mode in response to detecting that the handle is attached.

25. The autonomous mowing robot of claim 22, wherein the handle comprises a kill switch in communication with the drive system, the kill switch configured to send a signal to turn off the mowing robot when the kill switch is not activated.