Method and System for Multi-Mode Coverage For An Autonomous Robot

• US 20100049365A1
• Filed: 10/30/2009
• Published: 02/25/2010
• Est. Priority Date: 06/12/2001
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Mass, Philip R., Jones, Joseph L.
• Granted Patent: US 8,463,438 B2
• Time in Patent Office: Days
• US Class Current: 700/253
• CPC Class Codes: A47L 11/00 Machines for cleaning floors, carpets, furniture, walls, or wall coverings
• CPC Class Codes: B25J 11/0085 Cleaning
• CPC Class Codes: B25J 9/1694 characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion
• CPC Class Codes: G05D 1/0219 ensuring the processing of the whole working surface
• CPC Class Codes: G05D 1/0227 using mechanical sensing means, e.g. for sensing treated area
• CPC Class Codes: G05D 1/0242 using non-visible light signals, e.g. IR or UV signals
• 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 1/0272 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
• CPC Class Codes: Y10S 901/01 Mobile robot

Abstract

A control system for a mobile robot (10) is provided to effectively cover a given area by operating in a plurality of modes, including an obstacle following mode (51) and a random bounce mode (49). In other embodiments, spot coverage, such as spiraling (45), or other modes are also used to increase effectiveness. In addition, a behavior based architecture is used to implement the control system, and various escape behaviors are used to ensure full coverage.

Claims

1-2. -2. (canceled)

3. A mobile robot comprising:

a drive mechanism that both drives the robot forward in a drive direction and turns the robot to change the drive direction;

a floor cleaner disposed on a first lateral side of the robot, transverse to the drive direction;

a forward obstacle sensor system responsive to objects encountered by the robot while moving in the drive direction, the forward obstacle sensor system comprising first and second obstacle sensors disposed on a forward portion of the robot, wherein the first obstacle sensor is disposed on the first lateral side of the robot and the second obstacle sensor is disposed on an opposite, second lateral side of the robot with respect to the drive direction;

a side sensor positioned to detect proximity of objects on the first lateral side of the robot, transverse to the drive direction; and

a drive controller that controls the drive mechanism to turn the robot;

wherein in response to detecting an object by the forward obstacle sensor system proximate the forward portion of the robot, the drive controller determines an approximate approach angle between the drive direction and the detected object, and when the approach angle is on the second lateral side of the robot with respect to the drive direction, the drive controller turns the robot to detect with the side sensor proximity of the object on the first lateral side of the robot to position the floor cleaner substantially adjacent the detected object, and then drives the robot in the drive direction to follow the detected object proximate the first lateral side with the floor cleaner substantially adjacent the detected object.

4. The mobile robot of claim 3, wherein the floor cleaner includes a side brush extending beyond a lateral extent of a housing of the robot, the side brush arranged to sweep debris from beyond a perimeter of the robot for collection by the robot.

5. The mobile robot of claim 4, wherein the forward obstacle sensor system and the side sensor are both responsive to walls, and wherein the drive controller, in response to the forward sensor system detecting a wall in the drive direction, turns the robot until the detected wall is detected on the first lateral side of the robot, and then drives the robot to keep the detected wall on the first lateral side of the robot.

6. The mobile robot of claim 3, wherein the drive controller is further configured to

drive the robot to follow an object detected on the first lateral side of the robot, by changing a turning radius to maintain detection of the sensed object by the side sensor;

and

upon detecting that the object is no longer proximate the first lateral side of the robot, to initiate a turn of the robot toward the first lateral side of the robot in accordance with a turning radius in response to detecting that the followed object is no longer proximate the first lateral side; and

then to progressively decrease the turning radius of the robot over time while driving the robot forward, thereby causing the robot to turn more sharply until the robot encounters a change in sensory input.

7. The mobile robot of claim 3, wherein the drive controller determines that an object is no longer proximate the first lateral side of the robot upon transition of the side sensor from a reflection state to a non-reflection state.

8. The mobile robot of claim 3 wherein the drive controller is configured to drive the robot to turn in a spiral having a steadily increasing radius, such that the first lateral side of the robot is positioned on an outward edge of the spiral.

9. The mobile robot of claim 3, further comprising a bump sensor responsive to the robot bumping into an object in the drive direction, and wherein the drive controller, in response to the robot bumping into an object in the drive direction while the robot is following an object on the first lateral side of the robot, turns the robot away from the first lateral side of the robot through a first angle, stops turning the robot when the side sensor detects the bumped object, and then drives the robot forward in the drive direction, such that the robot tends to travel along the bumped object.

10. The mobile robot of claim 9, wherein the drive controller, in response to turning the robot away from the first lateral side of the robot through a turn angle larger than the first angle, without detecting the bumped object with the side sensor, stops turning the robot and then drives the robot forward in the drive direction.

11. A mobile robot comprising:

a drive mechanism that both drives the robot forward across a floor in a drive direction and turns the robot to change the drive direction;

a sensor responsive to proximity of an object to be followed on a lateral side of the robot;

a floor area cleaner disposed on the lateral side of the robot; and

a drive controller that controls the drive mechanism to turn the robot to follow the object on the lateral side of the robot, by changing a robot turning radius to maintain continuous detection of the object by the sensor, including turning the robot toward the lateral side while decreasing the robot turning radius in response to cessation of detection of the object proximate the lateral side;

wherein the controller controls the drive mechanism to follow a path having a turning radius proportional to an angle of turn.

12. The mobile robot of claim 11, wherein the controller sets an initial turning radius and steadily decreases the turning radius until the robot bumps against an object.

13. The mobile robot of claim 11, further comprising a cleaning head arranged to clean a floor surface over which the robot is driven, wherein the cleaning head has a width perpendicular to the drive direction, and wherein the turning radius is determined according to the relationship:

turning radius=θ

/(2π

) times a value less than the width of the cleaning head, where “

θ

”

is a cumulative turning angle (in radians) from turning initiation.

14. The mobile robot of claim 11, wherein the sensor is a reflection detector, and wherein the controller determines cessation of detection of the object upon the sensor transitioning from a reflection state to a non-reflection state.

15. The mobile robot of claim 11, wherein the controller decreases the robot turning radius until the sensor detects an object on the lateral side.

16. The mobile robot of claim 11, wherein the sensor is responsive to proximity of a room wall, and wherein the controller drives the robot to follow a proximate wall on the lateral side of the robot by changing a turning radius to maintain continuous detection of the wall by the sensor, including turning the robot toward the lateral side while decreasing the turning radius of the robot in response to cessation of detection of the wall proximate the lateral side.

17. The mobile robot of claim 16, wherein the controller

turns the robot through a minimum turn angle in response to a bump sensor on the robot detecting a bump of the robot against a wall while the robot is wall-following, and

stops turning the robot when the sensor detects the bumped wall, thereby substantially aligning the robot with the bumped wall.

18. The mobile robot of claim 17, wherein the controller stops turning the robot at a maximum turn angle, and then moves the robot forward along the drive direction.

19. The mobile robot of claim 17, wherein the controller determines the minimum turn angle in relation to a direction in which the bumped the wall.

20. A mobile robot comprising:

a drive mechanism that both drives the robot forward across a floor in a drive direction and turns the robot to change the drive direction;

a proximity sensor responsive to proximity of an object to be followed on a lateral side of the robot; and

a drive controller that controls the drive mechanism to turn the robot to follow the object on the lateral side of the robot, by changing a robot turning radius to maintain continuous detection of the object by the sensor, including turning the robot toward the lateral side in response to cessation of detection of the object proximate the lateral side;

wherein the proximity sensor is configured to detect the proximity of an object located approximately three inches ahead of a drive wheel of the drive mechanism in the drive direction.

21. The mobile robot of claim 20, wherein the proximity sensor comprises an emitter having an emission field and a detector having a detection field, the emitter and the detector both collimated to have a finite volume of intersection of the emission and detection fields with a focus point located approximately three inches ahead of a drive wheel of the drive mechanism in the drive direction.

22. The mobile robot of claim 20, wherein the proximity sensor has a radial detection range of about 0.75 inches.

23. The mobile robot of claim 20, wherein the controller decreases the robot turning radius until the proximity sensor detects an object on the lateral side.

24. The mobile robot of claim 20, wherein the controller sets an initial turning radius and steadily decreases the turning radius until the robot bumps against an object.

25. The mobile robot of claim 20, further comprising a cleaning head arranged to clean a floor surface over which the robot is driven, wherein the cleaning head has a width perpendicular to the drive direction, and wherein the turning radius is determined according to the relationship:

turning radius=θ

/(2π

) times a value less than the width of the cleaning head, where “

θ

”

is a cumulative turning angle (in radians) from turning initiation.

26. The mobile robot of claim 20, wherein the sensor is responsive to proximity of a room wall, and wherein the controller drives the robot to follow a proximate wall on the lateral side of the robot by changing a turning radius to maintain continuous detection of the wall by the sensor, including turning the robot toward the lateral side while decreasing the turning radius of the robot in response to cessation of detection of the wall proximate the lateral side.

27. A mobile robot comprising:

a chassis;

a drive mechanism disposed on the chassis that both drives the robot forward across a floor in a drive direction and turns the robot to change the drive direction;

a cleaning head disposed on the chassis; and

a drive controller that controls the drive mechanism and the cleaning head;

wherein in response to receiving a signal identifying a specific dirty region of the floor for cleaning, the drive controller directing the drive mechanism to drive the robot in a pattern that brings the cleaning head in contact with substantially all of the dirty floor region over a period of time.

28. The mobile robot of claim 27, wherein the controller executes a control algorithm for directing the drive mechanism to drive the robot in a pattern that brings the cleaning head in contact with substantially all of the dirty floor region over a period of time.

29. The mobile robot of claim 28, wherein the drive controller directs the drive mechanism to drive the robot back and forth over the dirty floor region.

30. The mobile robot of claim 29, wherein the drive controller directs the drive mechanism to drive the robot in a outward spirally pattern over the dirty floor region by increasing the turning radius as a function of time.

31. The mobile robot of claim 29, wherein the drive controller drives the robot over the dirty floor region until a proximity sensor responsive to proximity of an object on a lateral side of the robot detects an object on the lateral side.

32. The mobile robot of claim 31, wherein the proximity sensor comprises an emitter having an emission field and a detector having a detection field, the emitter and the detector both collimated to have a finite volume of intersection of the emission and detection fields with a focus point located approximately three inches ahead of a drive wheel of the drive mechanism in the drive direction.

33. The mobile robot of claim 29, wherein the drive controller drives the robot over the dirty floor region until the robot bumps against an object.

34. The mobile robot of claim 29, wherein the drive controller drives the robot over the dirty floor region until a cliff sensor in communication with the drive controller detects a cliff.