COVERAGE ROBOT NAVIGATING

• US 20120173070A1
• Filed: 12/30/2011
• Published: 07/05/2012
• Est. Priority Date: 12/30/2010
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Schnittman, Mark Steven
• Granted Patent: US 9,436,185 B2
• Time in Patent Office: Days
• US Class Current: 701/26
• CPC Class Codes: G05D 1/0227 using mechanical sensing means, e.g. for sensing treated area
• CPC Class Codes: G05D 1/024 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/0242 using non-visible light signals, e.g. IR or UV signals
• CPC Class Codes: G05D 1/0246 using a video camera in combination with image processing means
• 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 1/027 comprising intertial navigation means, e.g. azimuth detector inertial navigation G01C21/16; inertial navigation combined with non-inertial navigation instruments G01C21/165
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00

Abstract

A method of navigating an autonomous coverage robot on a floor includes controlling movement of the robot across the floor in a cleaning mode, receiving a sensor signal indicative of an obstacle, rotating the robot away from the sensed obstacle, determining a change in the received sensor signal during at least a portion of the rotation of the robot away from the sensed obstacle, and identifying the sensed obstacle based at least in part on the determined change in the received sensor signal.

Claims

1. A method of navigating an autonomous coverage robot on a floor, the method comprising:

controlling movement of the robot across the floor in a cleaning mode;

receiving a sensor signal indicative of an obstacle;

rotating the robot away from the sensed obstacle;

determining a change in the received sensor signal during at least a portion of the rotation of the robot away from the sensed obstacle; and

identifying the sensed obstacle based at least in part on the determined change in the received sensor signal.

2. The method of claim 1 wherein receiving the sensor signal indicative of an obstacle comprises determining an increase in the received sensor signal strength.

3. The method of claim 2 wherein determining the increase in the received sensor signal strength comprises low pass filtering the received sensor signal and comparing the low pass filtered sensor signal to an instantaneous sensor signal.

4. The method of claim 1 wherein determining the change in the received sensor signal comprises determining a peak in the strength of the received sensor signal.

5. The method of claim 4 wherein determining the peak in the strength of the received sensor signal comprises low pass filtering the received sensor signal and comparing the low pass filtered sensor signal to an instantaneous sensor signal.

6. The method of claim 1 wherein identifying the sensed obstacle based at least in part on the determined change in the received sensor signal comprises storing a first robot heading associated with the received sensor signal indicative of the obstacle and storing a second robot heading associated with the determined peak in the received sensor signal.

7. The method of claim 6 wherein identifying the sensed obstacle further comprises determining the angular width of the sensed obstacle based at least in part on the difference between the stored first and second robot headings and comparing the determined angular width of the sensed obstacle to a threshold.

8. The method of claim 7 wherein the threshold is set based at least in part on the strength of the received sensor signal and/or the angular width of the obstacle.

9. The method of claim 7 wherein the robot defines a fore-aft axis and the sensor signal, indicative of the obstacle, is received from one of a first sensor and a second sensor, the first sensor and the second sensor disposed on respective right and left sides of the fore-aft axis.

10. The method of claim 9 further comprising maneuvering the robot to orient the fore-aft axis substantially parallel to the sensed obstacle if the determined angular width of the obstacle is less than the threshold.

11. The method of claim 10 wherein maneuvering the robot to orient the fore-aft axis substantially parallel to the sensed obstacle comprises positioning the robot such that the sensor corresponding to the received sensor signal is closest to the sensed obstacle.

12. The method of claim 7 further comprising, upon determining that the angular width of the obstacle is less than the threshold, directing the robot to turn toward the sensed obstacle.

13. The method of claim 12 wherein the robot is substantially cylindrical and directing the robot to turn toward the sensed obstacle comprises turning the robot with a radius slightly larger than the radius of the robot.

14. The method of claim 12 wherein the robot is directed to turn with a radius about equal to the radius of the robot to about 1.8 times the radius of the robot.

15. The method of claim 12 wherein the robot is directed to turn with a turn radius based at least in part on the determined angular width of the obstacle.

16. The method of claim 12 wherein directing the robot to turn toward the sensed obstacle comprises directing the robot to turn until the first robot heading is reached and, upon reaching the first robot heading, directing the robot to move along a substantially straight path corresponding to the first robot heading.

17. The method of claim 7 further comprising, upon determining that the angular width of the sensed obstacle is greater than or equal to the threshold, maneuvering the robot to follow the sensed obstacle at a substantially fixed distance by changing a turning radius of the robot.

18. The method of claim 17 wherein changing the turning radius of the robot comprises turning the robot in a first direction away from the sensed obstacle and, upon determining that the sensor signal is no longer detected, turning the robot in a second direction toward the sensed obstacle.

19. The method of claim 7 wherein at least one of the stored first and second robot headings are determined by a gyroscope carried by the robot.

20. The method of claim 7 wherein at least one of the stored first and second robot headings is determined by a wheel encoder of a wheel supporting at least a portion of the robot above the cleaning surface.

21. The method of claim 1 further comprising, upon receiving a sensor signal indicative of an obstacle, moving the robot along a substantially straight line, in a direction opposite the received sensor signal.

22. The method of claim 21 wherein the robot is moved along the substantially straight line by a distance of about 15 mm to about 50 mm.

23. The method of claim 1 further comprising reducing the speed of the coverage robot across the floor in a cleaning mode based at least in part on the received sensor signal indicative of the obstacle.

24. A method of navigating an autonomous coverage robot on a floor, the method comprising:

storing a heading of the autonomous coverage robot;

moving the autonomous coverage robot along the stored heading to an obstacle tangent to a turning circle of the autonomous coverage robot;

scanning a sensor carried on the autonomous coverage robot;

receiving the scanned sensor signals;

classifying the obstacle based at least in part on the received scanned sensor signals;

orbiting the autonomous coverage robot around at least a portion of the classified obstacle based at least in part on classification of the obstacle as a post;

comparing the stored heading to the heading of the autonomous coverage robot during orbiting of the classified obstacle; and

resuming the stored heading based at least in part on the comparison of the stored heading to the heading of the autonomous coverage robot during orbiting.

25. The method of navigating the autonomous coverage robot of claim 24 wherein resuming the stored heading comprises interrupting the orbit of the autonomous coverage robot if the heading of the autonomous coverage robot during orbiting equals the stored heading.

26. The method of navigating the autonomous coverage robot of claim 24 wherein resuming the stored heading comprises turning the autonomous coverage robot toward the stored heading.

27. The method of navigating the autonomous coverage robot of claim 26 wherein turning the autonomous coverage robot toward the stored heading comprises turning the autonomous coverage robot in a direction opposite the direction of orbit of the autonomous coverage robot.

28. The method of navigating the autonomous coverage robot of claim 24 wherein orbiting the autonomous coverage robot comprises moving the autonomous coverage robot with a radius greater than a turning perimeter of the autonomous coverage robot.

29. The method of navigating the autonomous coverage robot of claim 24 wherein classifying the obstacle based at least in part on the received scanned sensor signals comprises comparison of the scanned sensor signals to an empirical model.

30. The method of navigating the autonomous coverage robot of claim 24 wherein scanning the sensor carried on the autonomous coverage robot comprises turning the autonomous coverage robot to move the sensor.

31. The method of navigating the autonomous coverage robot of claim 24 wherein scanning the sensor carried on the autonomous coverage robot comprises moving the sensor relative to the autonomous coverage robot.

32. The method of navigating the autonomous coverage robot of claim 24 wherein the sensor comprises one or more of the following:

a camera, a laser, and a proximity sensor, and an acoustic sensor.