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

• US 7,429,843 B2
• Filed: 06/29/2007
• Issued: 09/30/2008
• 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:
  US11/771,356
• Publication Number:
  US 20080001566A1
• Time in Patent Office: 459 Days
• Field of Search: 318/568.12, 318/587, 318/568.1, 318/568.11, 318/568.13, 901/1, 701/1, 701/23, 700/245
• 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 in a drive direction over a support surface and turns the robot to change the drive direction;

a forward obstacle sensor responsive to objects encountered by the robot while moving in the drive direction;

a side sensor positioned to detect proximity of objects on a dominant side of the robot, transverse to the direction of travel;

a side brush effective on the dominant side of the robot, the side brush extending from the dominant side of the robot and operating to sweep debris from beyond a robot perimeter for collection by the robot; and

a drive controller controlling the drive mechanism such that when the forward sensor detects an object in the direction of travel of the robot, the drive controller turns the robot to locate the detected object on the dominant side of the robot and drives the robot to keep the detected object on the dominant side of the robot, while the side brush processes a portion of the support surface adjacent the object on the dominant side;

wherein the drive controller turns the robot in response to the forward obstacle sensor detecting a wall, so as to position the detected wall on the dominant side of the robot as the side brush sweeps debris from between the robot perimeter and the wall.

5. The mobile robot of claim 1, wherein the drive controller is configured to drive the robot in a spiral having a steadily increasing radius, while keeping the dominant side of the robot facing outward with respect to the spiral.

6. The mobile robot of claim 1 further comprising a bump sensor, wherein the drive controller is configured to

turn the robot away from the dominant side by a minimum turn angle in response to the bump sensor signaling detection of a bump of the robot against an obstacle while the robot is following an object on the dominant side, and to

continue turning the robot until the dominant side sensor detects an adjacent object, thereby aligning the robot with the obstacle.

7. The mobile robot of claim 1, wherein the drive controller is configured to

turn the robot away from the dominant side through a minimum turn angle in response to the robot bumping against an obstacle while the robot is following an object on the dominant side, to

stop turning the robot at a maximum turn angle, and then drive the robot forward.

2. A mobile robot comprising:

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

a forward obstacle sensor responsive to objects encountered by the robot while moving in the drive direction;

a side sensor positioned to detect proximity of objects on a dominant side of the robot, transverse to the direction of travel;

a cleaning head effective on the dominant side of the robot; and

a drive controller controlling the drive mechanism such that when the forward sensor detects an object in the direction of travel of the robot, the drive controller turns the robot to locate the detected object on the dominant side of the robot and drives the robot to keep the detected object on the dominant side of the robot, while the cleaning head processes a portion of the support surface adjacent the object on the dominant side;

wherein the drive controller drives the robot to follow an object on the dominant side of the robot by

changing a turning radius while maintaining a continuous detection of the object by the side sensor,

monitoring the side sensor to detect an absence of the object after turning away from the object on the dominant side of the robot, and

monitoring the side sensor to detect the object after turning toward the object on the dominant side of the robot.

3. The mobile robot of claim 2, wherein the drive controller decreases the turning radius toward the dominant side of the robot so that the robot tends to enter and traverse passageways between objects.

4. A mobile robot comprising:

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

a forward obstacle sensor responsive to objects encountered by the robot while moving in the drive direction;

a side sensor positioned to detect proximity of objects on a dominant side of the robot, transverse to the direction of travel;

a cleaning head effective on the dominant side of the robot; and

a drive controller controlling the drive mechanism such that when the forward sensor detects an object in the direction of travel of the robot, the drive controller turns the robot to locate the detected object on the dominant side of the robot and drives the robot to keep the detected object on the dominant side of the robot, while the cleaning head processes a portion of the support surface adjacent the object on the dominant side;

wherein the controller is configured to

monitor the side sensor to detect an absence of the object after turning away from the object on the dominant side of the robot, by determining a transition from a reflection state to a non-reflection state of the dominant side sensor, and then to

turn the robot toward the dominant side of the robot until detecting the object, in response to the side sensor transitioning from the non-reflection state to the reflection state.