Obstacle following sensor scheme for a mobile robot

• US 20050251292A1
• Filed: 06/24/2005
• Published: 11/10/2005
• Est. Priority Date: 01/24/2000
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Cross, Matthew, Jones, Joseph L., Ozick, Daniel, Casey, Christopher
• Granted Patent: US 8,412,377 B2
• Time in Patent Office: Days
• US Class Current: 700/245
• 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: 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. A method for operating a mobile robot, the method comprising the steps of:

detecting the presence of an object proximate the mobile robot;

sensing a value of a signal corresponding to the object;

comparing the value to a predetermined value;

moving the mobile robot in response to the comparison; and

updating the predetermined value upon the occurrence of an event.

2. The method of claim 1, wherein the updated predetermined value is based at least in part on a product of the predetermined value and a constant.

3. The method of claim 1, wherein the event comprises a physical contact between the mobile robot and the object.

4. The method of claim 1, wherein the event comprises when a scaled value is less than the predetermined value.

5. The method of claim 1, wherein the scaled value is based at least in part on a product of the value and a constant.

6. The method of claim 1, wherein the step of moving the mobile robot comprises causing the robot to travel toward the object, when the value is less than the predetermined value.

7. The method of claim 1, wherein the step of moving the mobile robot comprises causing the robot to travel away from the object, when the value is greater than the predetermined value.

8. The method of claim 1, further comprising conditioning the value of the signal corresponding to the object.

9. The method of claim 1, wherein the detection step comprises:

a first detection at a first distance to the object; and

a second detection at a second distance to the object.

10. The method of claim 1, wherein the detection step comprises emitting at least one signal.

11. The method of claim 1, wherein the detection step comprises measuring at least one signal with at least one sensor.

12. The method of claim 11, wherein a plurality of signals are averaged.

13. The method of claim 11, wherein the at least one signal is filtered.

14. The method of claim 11, wherein a plurality of sensors are disposed on the mobile robot in a predetermined pattern.

15. The method of claim 14, wherein the predetermined pattern accomodates a variation in object reflectivity.

16. The method of claim 10, further comprising the step of varying power of the at least one emitted signal.

17. The method of claim 11, further comprising the step of varying sensitivity of the at least one sensor.

18. The method of claim 10, wherein the at least one emitted signal comprises light having at least one of a visible wavelength and an infrared wavelength.

19. The method of claim 11, wherein the at least one signal comprises light having at least one of a visible wavelength and an infrared wavelength.

20. The method of claim 10, wherein the at least one emitted signal comprises an acoustic wave having at least one of an audible frequency and an ultrasonic frequency.

21. The method of claim 11, wherein the at least one signal comprises an acoustic wave having at least one of an audible frequency and an ultrasonic frequency.

22. The method of claim 1, wherein the mobile robot comprises:

at least one infrared emitter; and

at least one infrared detector;

wherein the at least one infrared emitter and the at least one infrared detector are oriented substantially parallel to each other.

23. The method of claim 1, wherein the value corresponds to at least one of a distance to the object and an albedo of the object.

24. A method for operating a mobile robot, the method comprising:

detecting a presence of an object proximate the mobile robot;

detecting an absence of the object;

moving the robot a predetermined distance in a predetermined first direction; and

rotating the robot in a predetermined second direction about a fixed point.

25. The method of claim 24, wherein the predetermined distance corresponds at least in part to a distance substantially from a sensor located on the robot to a robot wheel axis.

26. The method of claim 24, wherein the first direction is defined at least in part by a direction of motion of the robot prior to detecting the absence of the object.

27. The method of claim 24, wherein the fixed point comprises a point between a first wheel of the robot and the object.

28. The method of claim 27, wherein the first wheel is proximate the object.

29. The method of claim 24, further comprising the step of ceasing rotating the robot upon an occurrence of an event.

30. The method of claim 29, wherein the event comprises detecting a presence of an object.

31. The method of claim 29, wherein the event comprises contacting an object.

32. The method of claim 29, wherein the event comprises rotating the robot beyond a predetermined angle.

33. The method of claim 24, further comprising the step of moving in a third direction.