Detecting robot stasis

Patent metadata

Field	Value
Publication number	US-9317038-B2
Application number	US-201313777648-A
Country	US
Kind code	B2
Filing date	Feb 26, 2013
Priority date	May 31, 2006
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

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.

First claim

What is claimed is:

1. A coverage robot comprising:
a body;
a wheeled-drive that maneuvers the body over a surface according to drive commands from a controller in communication with the drive;
a first stasis sensor carried on the body, and responsive to surface-relative movement of the body, the first stasis sensor comprising:
a swivel caster assembly comprising a stasis indication wheel freely rotatable about a horizontal axis parallel to the surface and freely rotatable about a second axis at an angle relative to the horizontal axis such that rotation about the second axis causes the wheel to swivel on the surface; and
a non-contact wheel sensor defining an area of detection around the stasis indication wheel as the wheel freely rotates about the horizontal axis and as the wheel swivels on the surface; and

a second stasis sensor carried separately on the body from the first stasis sensor, and responsive to surface-relative movement of the body,
wherein the controller is configured to:
concurrently monitor sensory output from each of the first and second stasis sensors; and
determine whether the robot is in a substantially stuck condition or at least partially disengaged from the surface as a function of the drive commands and sensory output from each of the first and second stasis sensors.

2. The coverage robot of claim 1 , wherein the controller is further configured to transition from the first stasis sensor to the second stasis sensor as a primary sensor.

3. The coverage robot of claim 2 , wherein the controller comprises a transition algorithm to cause a unitary transition from the first stasis sensor to the second stasis sensor.

4. The coverage robot of claim 2 , wherein the controller comprises a transition algorithm to cause a progressive transition over time from the first stasis sensor to the second stasis sensor.

5. The coverage robot of claim 2 , wherein the controller is further configured to determine when the efficacy of the sensory output from the first stasis sensor has degraded below a predetermined threshold, and to initiate the transition in response to the degradation determination.

6. The coverage robot of claim 1 , wherein the controller is further configured to integrate received sensory output from the first stasis sensor with sensory output from the second stasis sensor.

7. The coverage robot of claim 1 , wherein the stasis indication wheel comprises a bi-colored wheel with one or more light sections and one or more dark sections, and wherein the wheel sensor comprises an optical sensor that detects transitions between the light and dark sections as the stasis indication wheel spins.

8. The coverage robot of claim 7 , wherein the one or more light sections of the stasis indication wheel reflect light of a first infrared wavelength and the one or more dark sections reflect light of a second infrared wavelength different from the first wavelength.

9. The coverage robot of claim 7 , wherein the optical sensor comprises:
a signal emitter disposed remotely from the stasis indication wheel and positioned to direct a signal that sequentially is intercepted by the light and dark sections of the stasis indication wheel; and
a signal receiver positioned to receive the signal as reflected by the stasis indication wheel as the stasis indication wheel rotates with respect to the emitter.

10. The coverage robot of claim 1 , wherein the stasis indication wheel comprises one or more magnetic sections and one or more non-magnetic sections, and wherein the wheel sensor is responsive to the magnetic sections.

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

12. The coverage robot of claim 1 , further comprising a drop wheel sensor arranged to detect vertical displacement of the stasis indication wheel.

13. The coverage robot of claim 1 , further comprising a wheel housing carried by the body and shrouding the stasis indication wheel, the wheel housing defining an aperture in a top portion of the wheel housing, exposing the stasis indication wheel to the wheel sensor.

14. The coverage robot of claim 13 , wherein the wheel housing is configured to minimize an entry of ambient light into the aperture of the housing.

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

16. The coverage robot of claim 1 , wherein at least one of the first and second stasis sensors comprises a drive motor sensor monitoring a drive motor of the wheeled-drive.

17. The coverage robot of claim 16 , wherein the drive motor sensor monitors a drive current drawn by the drive motor.

18. 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 proximate the body, 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 body.

19. The coverage robot of claim 1 , wherein the substantially stuck condition is a condition in which one or more wheels of the wheeled-drive are rotating while the robot remains stationary relative to the surface.

20. A coverage robot comprising:
a body;
a wheeled-drive that maneuvers the body over a surface according to drive commands from a controller in communication with the drive;
a first stasis sensor carried on the body, and responsive to surface-relative movement of the body, the first stasis sensor comprising:
swivel caster assembly comprising a stasis indication wheel freely rotatable about a horizontal axis parallel to the surface and freely rotatable about a second axis at an angle relative to the horizontal axis such that rotation about the second axis causes the wheel to swivel on the surface; and
a non-contact wheel sensor defining an area of detection around the stasis indication wheel as the wheel freely rotates about the horizontal axis and as the wheel swivels on the surface; and

a second stasis sensor carried separately on the body from the first stasis sensor, and responsive to surface-relative movement of the body, the second stasis sensor comprising a drive motor sensor monitoring a drive current drawn by a drive motor of the wheeled-drive,
wherein the controller is configured to:
concurrently monitor sensory output from each of the first and second stasis sensors; and
determine whether the robot is in a substantially stuck condition or at least partially disengaged from the surface as a function of the drive commands and sensory output from each of the first and second stasis sensors.

Assignees

• Irobot Corp

Inventors

• Ozick Daniel N
• Gilbert Jr Duane L

Classifications

• A47L9/2826

  the condition of the floor · CPC title

• A47L9/009

  Carrying-vehicles; Arrangements of trollies or wheels; Means for avoiding mechanical obstacles · CPC title

• A47L2201/04

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

• A47L2201/00

  Robotic cleaning machines, i.e. with automatic control of the travelling movement or the cleaning operation · CPC title

• G05D1/0231 Primary

  using optical position detecting means (position-fixing by using electromagnetic waves other than radio waves, e.g. optical position detecting means G01S5/16) · CPC title