Method and system for multi-mode coverage for an autonomous robot

• US 7,663,333 B2
• Filed: 06/29/2007
• Issued: 02/16/2010
• Est. Priority Date: 06/12/2001
• Status: Expired due to Term

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Mass, Philip R., Jones, Joseph L.
• Primary Examiner(s): Leykin; Rita
• Application Number:
  US11/771,433
• Publication Number:
  US 20070285041A1
• Time in Patent Office: 963 Days
• Field of Search: 318/568.11, 318/568.12, 700/245, 700/258, 700/259, 901/1, 701/207, 701/225
• US Class Current: 318/568.12
• 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. 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;

an optical sensor responsive to proximity of an object to be followed on a lateral side of the robot, the optical sensor comprising 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 ahead of a drive wheel of the drive mechanism in the drive direction;

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.

2. The mobile robot of claim 1, wherein the controller sets an initial turning radius and steadily decreases the turning radius until the robot bumps against an object.

3. The mobile robot of claim 1, 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.

4. The mobile robot of claim 1, wherein the controller decreases the robot turning radius until the sensor detects an object on the lateral side.

5. The mobile robot of claim 1, wherein the floor area cleaner comprises a side brush extending beyond a lateral extent of a housing of the robot, the side brush driven to sweep debris from a floor surface beyond the lateral extent of housing for collection by the robot.

6. 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;

a cleaning head arranged to clean a floor surface over which the robot is driven; 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 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.

7. 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;

a cleaning head arranged to clean a floor surface over which the robot is driven; 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 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;

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.

8. The mobile robot of claim 7, wherein the controller stops turning the robot at a maximum turn angle, and then moves the robot forward along the drive direction.

9. The mobile robot of claim 7, wherein the controller determines the minimum turn angle in relation to a direction in which the bumped the wall.