DETECTING ROBOT STASIS

• US 20080065265A1
• Filed: 05/31/2007
• Published: 03/13/2008
• Est. Priority Date: 05/31/2006
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Gilbert, Duane, Ozick, Daniel
• Granted Patent: US 8,417,383 B2
• Time in Patent Office: Days
• US Class Current: 700/245
• CPC Class Codes: A47L 2201/00 Robotic cleaning machines, i.e. with automatic control of the travelling movement or the cleaning operation
• CPC Class Codes: A47L 2201/04 Automatic control of the travelling movement; Automatic obstacle detection
• CPC Class Codes: A47L 9/009 Carrying-vehicles; Arrangements of trollies or wheels; Means for avoiding mechanical obstacles
• CPC Class Codes: A47L 9/2826 the condition of the floor
• CPC Class Codes: G05D 1/0227 using mechanical sensing means, e.g. for sensing treated area
• CPC Class Codes: G05D 1/0231 using optical position detecting means position-fixing by using electromagnetic waves other than radio waves, e.g. optical position detecting means G01S5/16

Abstract

A coverage robot includes a drive configured to maneuver the robot as directed by a controller, a stasis indication wheel rotatable about a first axis perpendicular to a direction of forward travel, and a suspension supporting the wheel. The stasis indication wheel defines a first reflective portion and a second reflective portion. The second reflective portion is substantially less reflective than the first reflective portion. The suspension permits movement of the wheel in a direction other than rotation about the first axis. A signal emitter is disposed remotely from the wheel and positioned to direct a signal that sequentially is intercepted by the first and second reflective portions of the wheel. A signal receiver is positioned to receive the reflected signal by the rotating wheel. Communication between the emitter and the receiver is affected by rolling transitions between the first and second reflective portions during permitted movement of the wheel.

Claims

1. A coverage robot comprising:

a drive configured to maneuver the robot as directed by a controller in communication with the drive;

a stasis indication wheel rotatable about a first axis perpendicular to a direction of forward travel, the stasis indication wheel defining a first reflective portion and a second reflective portion, the second reflective portion being substantially less reflective than the first reflective portion;

a suspension supporting the wheel and permitting movement of the wheel in a direction other than rotation about the first axis;

a signal emitter disposed remotely from the wheel and positioned to direct a signal that sequentially is intercepted by the first and second reflective portions of the wheel; and

a signal receiver positioned to receive the signal as reflected by the wheel as the wheel rotates with respect to the emitter and as the suspension permits movement of the wheel in a direction other than rotation about the first axis,

wherein communication between the emitter and the receiver is affected by rolling transitions between the first reflective portion and the second reflective portion of the wheel in multiple positions about the first axis and along permitted movement in a direction other than rotation about the first axis.

2. The coverage robot of claim 1 wherein the permitted direction of wheel movement other than rotation about the first axis comprises vertical displacement of the wheel.

3. The coverage robot of claim 2 further comprising a drop wheel sensor arranged to detect vertical displacement of the wheel.

4. The coverage robot of claim 1 wherein the permitted direction of wheel movement other than rotation about the first axis comprises tilting away from a vertical second axis perpendicular to the first axis.

5. The coverage robot of claim 1 wherein the permitted direction of wheel movement other than rotation about the first axis comprises rotation about a vertical second axis perpendicular to the first axis.

6. The coverage robot of claim 1 wherein the permitted direction of wheel movement other than rotation about the first axis comprises translation parallel to an underside of the robot.

7. The coverage robot of claim 1 further comprising a wheel housing secured to the suspension and shrouding the wheel, the wheel housing defining an aperture in a top portion of the wheel housing, exposing the wheel to the signal emitter and the signal receiver.

8. The coverage robot of claim 7 wherein the wheel housing is configured to minimize an entry of ambient light into the aperture of the housing.

9. The coverage robot of claim 1 wherein the reflective portion of the wheel reflects light of a first infrared wavelength and the non-reflective portion reflects light of a second infrared wavelength different from the first wavelength.

10. The coverage robot of claim 1 wherein the emitter and receiver are arranged above the wheel, the emitter emitting the signal onto a top portion of the wheel, and the receiver responsive to reflected emissions.

11. The coverage robot of claim 1 further comprising a cliff signal emitter and a cliff signal receiver, the cliff signal emitter aligned to emit a cliff detection signal onto a floor surface adjacent the wheel, the cliff signal receiver configured to receive the cliff detection signal reflected from the floor surface;

wherein the cliff signal emitter and cliff signal receiver are arranged with respect to the floor surface such that communication between the cliff signal emitter and the cliff signal receiver is affected by vertical movement of the floor surface with respect to the robot.

12. The coverage robot of claim 1 wherein the controller monitors a drive current of the drive to determine a presence of a stasis condition.

13. The coverage robot of claim 1 wherein the stasis indication wheel comprises a hub and multiple spokes extending outwardly from the hub.

14. The coverage robot of claim 1 wherein the stasis indication wheel is disposed adjacent a drive wheel.

15. A coverage robot comprising:

a drive configured to maneuver the robot as directed by a controller in communication with the drive;

a stasis indication wheel rotatable about a first axis perpendicular to a direction of forward travel and disposed adjacent the drive, the wheel comprising a hub and multiple spokes extending outwardly from the hub, the wheel defining a first reflective portion and a second reflective portion, the second reflective portion being substantially less reflective than the first reflective portion;

a signal emitter disposed remotely from the wheel and positioned to direct a signal that sequentially is intercepted by the first and second reflective portions of the wheel; and

a signal receiver positioned to receive the signal as reflected by the wheel as the wheel rotates with respect to the emitter and as the suspension permits movement of the wheel in a direction other than rotation about the first axis,

wherein communication between the emitter and the receiver is affected by rolling transitions between the first reflective portion and the second reflective portion of the wheel in multiple positions about the first axis and along permitted movement in a direction other than rotation about the first axis.

16. The coverage robot of claim 15 wherein the spokes of the stasis indication wheel spiral outwardly from the hub.

17. The coverage robot of claim 15 wherein the spokes of the stasis indication wheel are compliant.

18. The coverage robot of claim 15 wherein the stasis indication wheel includes a magnet disposed on one of the spokes, the magnet interacts with a reed switch in communication with the controller.

19. The coverage robot of claim 15 wherein the reflective portion of the wheel reflects light of a first infrared wavelength and the non-reflective portion reflects light of a second infrared wavelength different from the first wavelength.

20. The coverage robot of claim 15 wherein the emitter and receiver are arranged above the wheel, the emitter emitting the signal onto a top portion of the wheel, and the receiver responsive to reflected emissions.

21. The coverage robot of claim 15 wherein the controller monitors a drive current of the drive to determine a presence of a stasis condition.