OBSTACLE FOLLOWING SENSOR SCHEME FOR A MOBILE ROBOT

• US 20090055022A1
• Filed: 05/23/2008
• Published: 02/26/2009
• Est. Priority Date: 01/24/2000
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Cross, Mathew, Casey, Christopher, Jones, Joseph L., Ozick, Daniel
• Granted Patent: US 8,478,442 B2
• Time in Patent Office: Days
• US Class Current: 700/258
• CPC Class Codes: A47L 2201/04 Automatic control of the travelling movement; Automatic obstacle detection
• CPC Class Codes: B25J 9/1697 Vision controlled systems
• CPC Class Codes: G01S 15/931 of land vehicles
• CPC Class Codes: G01S 17/93 for anti-collision purposes
• CPC Class Codes: G05D 1/0238 using obstacle or wall sensors G05D1/0246 and G05D1/0289 take precedence; lidar systems designed for anti-collision purposes G01S17/93
• CPC Class Codes: G05D 1/024 in combination with a laser lasers per se H01S
• 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 2201/0203 Cleaning or polishing vehicle
• CPC Class Codes: G05D 2201/0208 Lawn mower
• CPC Class Codes: G05D 2201/0215 Vacuum cleaner
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
• CPC Class Codes: Y10S 901/01 Mobile robot
• CPC Class Codes: Y10S 901/47 Optical

Abstract

A robot obstacle detection system including a robot housing which navigates with respect to a surface and a sensor subsystem aimed at the surface for detecting the surface. The sensor subsystem includes an emitter which emits a signal having a field of emission and a photon detector having a field of view which intersects the field of emission at a region. The subsystem detects the presence of an object proximate the mobile robot and determines a value of a signal corresponding to the object. It compares the value to a predetermined value, moves the mobile robot in response to the comparison, and updates the predetermined value upon the occurrence of an event.

Claims

1-38. -38. (canceled)

39. A robot comprising:

a substantially circular robot housing;

a drive system housed by the robot housing and configured to maneuver the robot with respect to a wall;

at least one sensor component in the robot housing directed for detecting the presence of the wall, the sensor component comprising;

an emitter that emits a directed beam having a defined field of emission; and

a detector having a defined field of view that intersects the field of emission of the emitter, the intersection of the field of emission and the field of view defining a volume of intersection space; and

a circuit in communication with the detector and the drive system configured to control the drive system to rotate the robot and configured to determine;

whether the detector detects the wall,

whether the robot is in contact with the wall, and

whether the robot has turned a predetermined angle without detecting or contacting the wall.

40. The robot of claim 39, wherein the circuit is configured to realign the robot for travel along the wall in response to determining that the detector detects the wall.

41. The robot of claim 39, further comprising a bump sensor in communication with the circuit for detecting when the robot is in contact with the wall.

42. The robot of claim 41, wherein the circuit is configured to realign the robot for travel along the wall in response to determining that the robot is in contact with the wall.

43. The robot of claim 39, wherein the circuit is configured to cease a wall seeking routine in response to determining that the robot has turned a predetermined angle without encountering the wall.

44. The robot of claim 39, wherein the detector is configured to detect a baseline level of ambient light and to detect the beam from the emitter.

45. The robot of claim 39, wherein the beam of the emitter is modulated and the detector comprises a modulation filter.

46. The robot of claim 39, wherein the circuit is configured to control the drive system to pivot the robot 180 degrees about a wall end to follow an opposing side of the wall.

47. The robot of claim 39, wherein the circuit is configured to control the drive system to maintain, as a function of the orientation of the robot with respect to the wall, a range of beam signal strength detected by the detector.

48. The robot of claim 47, wherein the circuit is configured to vary the radius of rotation of the robot in response to the difference between a detected beam signal value and a predetermined target signal value.

49. The robot of claim 39, wherein the circuit is configured to terminate a wall following routine in response to determining that the robot has rotated 360 degrees in following the wall or in seeking the wall since last detecting the wall.

50. The robot of claim 39, further comprising multiple detectors connected to the circuit in an OR logic configuration to provide an output to the circuit from any one of the multiple detectors.

51. The robot of claim 39 further comprising an emitter collimator about the emitter for directing the emission beam and a detector collimator about the photon detector to define the field of view, the emitter collimator and the detector collimator being angled with respect to the wall to define a finite volume of intersection space.

52. The robot of claim 39, wherein the volume of intersection space substantially defines a cone shape.

53. The robot of claim 39, wherein the circuit is configured to provide an output when a wall is not present in the volume of intersection space, the circuit output causing the robot to be directed back towards the wall while the wall does not occupy the intersection space.

54. The robot of claim 39 further comprising at least two edge cleaning heads carried on opposite sides of the housing and driven about a non-horizontal axis, each edge cleaning head extending beyond a lateral extent of the housing to engage the surface while the robot is maneuvered across the surface.

55. A method for operating a mobile robot, the method comprising the steps of:

detecting the presence of a wall;

driving the robot, based on the detecting, to follow the wall until the wall is no longer detected; and

rotating the robot to seek the wall while determining whether;

the wall is again detected,

the robot is in contact with the wall, and

the robot has turned a predetermined angle without detecting or contacting the wall.

56. The method of claim 55, further comprising realigning the robot for travel along the wall in response to contacting or again detecting the wall.

57. The method of claim 55, further comprising terminating a wall seeking routine in response to determining that the robot has turned a predetermined angle without encountering the wall.

58. The method of claim 55, further comprising detecting a level of ambient light and detecting a level of robot emitted light relative to the ambient light.

59. The method of claim 55, further comprising pivoting the robot 180 degrees about a wall end to follow an opposing side of the wall.

60. The method of claim 55, wherein driving the robot comprises maintaining a range of detected signal strength as a function of the orientation of the robot with respect to the wall.

61. The method of claim 55, further comprising varying the radius of rotation of the robot in response to the difference between a detected signal strength and a target signal strength.

62. The method of claim 55, further comprising terminating a wall following routine in response to determining that the robot has rotated 360 degrees in following the wall or in seeking the wall since last detecting the wall.

63. The method of claim 55, wherein detecting comprises defining a finite volume of intersection space between a signal emission region and a detection region and driving the robot comprises causing the robot to be directed back towards the wall while the wall does not occupy the intersection space.