MOBILE FLOOR-CLEANING ROBOT WITH FLOOR-TYPE DETECTION

• US 20160235270A1
• Filed: 02/13/2015
• Published: 08/18/2016
• Est. Priority Date: 02/13/2015
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Santini, Fabrizio
• Granted Patent: US 9,993,129 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A47L 11/4011 Regulation of the cleaning machine by electric means; Control systems and remote control systems therefor
• CPC Class Codes: A47L 11/4013 Contaminants collecting devices, i.e. hoppers, tanks or the like
• CPC Class Codes: A47L 11/4041 Roll shaped surface treating tools
• CPC Class Codes: A47L 11/4044 Vacuuming or pick-up tools; Squeegees
• CPC Class Codes: A47L 2201/04 Automatic control of the travelling movement; Automatic obstacle detection
• CPC Class Codes: A47L 2201/06 Control of the cleaning action for autonomous devices; Automatic detection of the surface condition before, during or after cleaning
• CPC Class Codes: A47L 9/0411 driven by electric motor
• CPC Class Codes: A47L 9/2826 the condition of the floor

Abstract

Cleaning robots may use floor-type-detection techniques as a trigger for autonomously altering various floor-cleaning characteristics. In some examples, a controller circuit of the robot is configured to determine a flooring type as a function of a signal from a motion sensor indicative of a change in pitch caused by the robot crossing a flooring discontinuity. In some examples, the controller circuit is configured to determine a flooring type based on a power draw signal corresponding to the cleaning head assembly of the robot.

Claims

1. A cleaning robot, comprising:

a chassis;

a drive connected to the chassis and configured to drive the robot across a floor surface;

a cleaning head assembly coupled to the chassis and positioned to engage the floor surface while the robot is maneuvered by the drive;

a motion sensor responsive to changes in pitch, the motion sensor being carried by the chassis; and

a controller circuit in communication with the cleaning head assembly and the motion sensor, the controller circuit configured to determine a flooring type associated with a cleaning characteristic of the robot and configured to alter the cleaning characteristic of the robot as a function of a signal from the motion sensor indicative of a change in pitch caused by the robot crossing a flooring discontinuity.

2. The cleaning robot of claim 1, wherein the cleaning head assembly comprises a motorized roller rotatably mounted parallel to the floor surface and configured to contact and agitate the floor surface during use.

3. The cleaning robot of claim 2, wherein the motorized roller comprises a front roller, and wherein the cleaning head further comprises a rear roller rotatably mounted parallel to the floor surface and spaced apart from the front roller by a small elongated gap.

4. The cleaning robot of claim 1, wherein the controller circuit is further configured to:

detect a change in pitch of the chassis based on feedback from the motion sensor, the change in pitch caused by the robot crossing a flooring discontinuity;

detect a change in operation of the cleaning head assembly; and

identify a change in flooring type of the floor surface in response to detecting the change in operation of the cleaning head assembly within a predetermined time of detecting the change in pitch.

5. The cleaning robot of claim 4, wherein the controller circuit is configured to detect a change in operation of the cleaning head assembly as a change in resistance to rotation of a motorized roller of the cleaning head.

6. The cleaning robot of claim 5, wherein the controller circuit is configured to detect a change in resistance to rotation of the roller as a change in power generated by a motor driving the roller.

7. The cleaning robot of claim 6, wherein the controller circuit is configured to monitor motor power as a function of one or more of motor current, battery voltage and motor speed.

8. The cleaning robot of claim 1, further comprising a cleaning bin carried by the chassis, and a motor driven fan located within the cleaning bin to provide a suction force that pulls debris into the cleaning bin, and

wherein altering a cleaning characteristic of the robot comprises altering the suction force.

9. The cleaning robot of claim 8, wherein altering the suction force comprises increasing the suction force in response to an identification by the controller circuit of a change across the flooring discontinuity from a hard floor surface to a soft floor surface.

10. The cleaning robot of claim 8, wherein altering the suction force comprises decreasing the suction force in response to an identification by the controller circuit of a change across the flooring discontinuity from a soft floor surface to a hard floor surface.

11. The cleaning robot of claim 1, wherein the motion sensor is a six-axis inertial measurement unit and comprises at least one of a three-axis gyroscope and a three-axis accelerometer.

12. The cleaning robot of claim 1, wherein the controller circuit is configured to identify a change in flooring type across the flooring discontinuity by determining a change in a class of the floor surface.

13. The cleaning robot of claim 12, wherein the controller circuit is configured to determine a class of the floor surface based on a signal representing operation of the cleaning head assembly.

14. The cleaning robot of claim 13, wherein the controller circuit is configured to determine a class of the floor surface by partitioning the signal based on a plurality of predetermined ranges.

15. The cleaning robot of claim 13, wherein the controller circuit is configured to determine a class of the floor surface based on a probabilistic classifier model.

16. The cleaning robot of claim 15, wherein the controller circuit is configured to alter the probabilistic classifier model in response to a detection of a change in pitch caused by the robot crossing a flooring discontinuity.

17. The cleaning robot of claim 16, wherein altering the probabilistic classifier model comprises increasing a probability of a floor-type change.

18. The cleaning robot of claim 16, wherein altering the probabilistic classifier model comprises resetting a current floor type.

19. The cleaning robot of claim 15, wherein the probabilistic classifier model comprises a Bayesian filter.

20. The cleaning robot of claim 12, wherein the controller is configured to suspend re-classification of the floor surface as the robot is driven in an arc by the drive.

21. A cleaning robot, comprising:

a chassis;

a drive connected to the chassis and configured to drive the robot across a floor surface;

a cleaning head assembly coupled to the chassis and positioned to engage the floor surface while the robot is maneuvered by the drive; and

a controller circuit in communication with the cleaning head assembly, the controller circuit configured to;

determine an initial raw class of the floor surface based on a power draw signal corresponding to the cleaning head assembly;

identify a change in the class of the floor surface; and

in response to identifying a floor-surface change from the initial raw class of the floor surface, modulating a cleaning characteristic of the robot,

wherein identifying a change in the class of floor surface comprises integrating data from a plurality of monitored inputs, the inputs including at least one of;

a cleaning head state signal;

a motion signal, and

an inertial measurement unit (IMU) signal.

22. The cleaning robot of claim 21, wherein identifying a change in class of the floor surface comprises:

determining that the robot is turning along a curved path on the floor surface based on the motion signal; and

in response to determining that the robot is turning, maintaining the cleaning characteristic at a current state.

23. The cleaning robot of claim 21, wherein identifying a change in class of the floor surface comprises:

determining that the robot is rotating in place on the floor surface based on the motion signal; and

in response to determining that the robot is rotating and not moving across a floor surface interface, maintaining the cleaning characteristic at a current state.

24. The cleaning robot of claim 23, wherein identifying a change in class of the floor surface comprises:

determining a turning radius and drive speed of the robot based on the motion signal; and

altering the cleaning characteristic in proportion to a magnitude of the turning radius.

25. The cleaning robot of claim 21, further comprising a cleaning bin carried by the chassis, and a motor driven fan located within the cleaning bin to provide a suction force that pulls debris into the cleaning bin, and

wherein modulating a cleaning characteristic of the robot comprises modulating the suction force.

26. The cleaning robot of claim 21, wherein integrating data from the plurality of monitored inputs comprises calculating a probability that a change in the power draw signal corresponds to a change in the class of the floor surface based on each of the inputs.

27. The cleaning robot of claim 26, wherein calculating a probability based on the motion signal comprises calculating a probability that the robot is performing at least one of a turn in place and an arched turn.

28. The cleaning robot of claim 26, wherein calculating a probability based on the cleaning head state signal comprises calculating a probability that a motor driving the cleaning head assembly has stalled.

29. The cleaning robot of claim 26, wherein calculating a probability based on the IMU signal comprises calculating a probability that the robot has crossed a flooring discontinuity.

30. The cleaning robot of claim 21, wherein determining an initial raw class of the floor surface comprises determining a most likely floor class based on empirical data stored in computer memory of the controller.

31. The cleaning robot of claim 30, wherein determining the most likely floor class comprises calculating a posterior probability distribution over a set of predefined floor-type classes based on a plurality of probability density functions stored in the computer memory.

32. The cleaning robot of claim 21, wherein the cleaning head assembly comprises a motorized roller rotatably mounted parallel to the floor surface and configured to contact and agitate the floor surface during use.

33. The cleaning robot of claim 32, wherein the motorized roller comprises a front roller, and wherein the cleaning head further comprises a rear roller rotatably mounted parallel to the floor surface and spaced apart from the front roller by a small elongated gap.