Robot obstacle detection system

• US 7,155,308 B2
• Filed: 06/03/2003
• Issued: 12/26/2006
• Est. Priority Date: 01/24/2000
• Status: Expired due to Term

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Jones, Joseph L.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): Marc, McDieunel
• Application Number:
  US10/453,202
• Publication Number:
  US 20040020000A1
• Time in Patent Office: 1,302 Days
• Field of Search: 700/245, 700/258, 318/568.1, 318/568.12, 318/568.16, 318/568.17, 701/23, 701 25- 26, 15/491, 153/19, 342/127, 250/559.33, 901/47
• US Class Current: 700/245
• 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

Abstract

A robot obstacle detection system including a robot housing which navigates with respect to a surface and a sensor subsystem having a defined relationship with respect to the housing and aimed at the surface for detecting the surface. The sensor subsystem includes an optical emitter which emits a directed beam having a defined field of emission and a photon detector having a defined field of view which intersects the field of emission of the emitter at a region. A circuit in communication with a detector redirects the robot when the surface does not occupy the region to avoid obstacles. A similar system is employed to detect walls.

Claims

1. A sensor subsystem for an autonomous robot which rides on a surface, the sensor subsystem comprising:

an optical emitter which emits a directed optical beam having a defined field of emission;

a photon detector having a defined field of view which intersects the field of emission of the emitter at a region; and

a circuit in communication with the detector providing an output when an object is not present in the region thereby re-directing the autonomous robot.

2. The system of claim 1 in which the object is the surface and the output from the circuit causes the robot to be directed to avoid an obstacle when the surface does not occupy the region of intersection between the defined field of emission of the emitter and the defined field of view of the detector.

3. The system of claim 1 in which the object is a wall and the output from the circuit causes the robot to be directed back towards the wall when the wall does not occupy the region of intersection of the defined field of emission of the emitter and the defined field of view of the detector.

4. The system of claim 3 in which the circuit includes logic which redirects the robot away from the wall when the wall occupies the region and back towards the wall when the wall no longer occupies the region of intersection.

5. The system of claim 4 in which the circuit includes logic which redirects the robot away from the wall when the wall occupies the region and then back towards the wall when the wall no longer occupies the region of intersection at decreasing radiuses of curvature until the wall once again occupies the region of intersection.

6. The system of claim 1 further including a plurality of sensor subsystems spaced from each other on the housing of the robot, the circuit including logic for detecting whether any detector of each said sensor subsystem has failed to detect a beam from an emitter.

7. The system of claim 1 in which the robot includes a surface cleaning brush.

8. The system of claim 1 in which the emitter includes an infrared light source and the detector includes an infrared photon detector.

9. The system of claim 8 further including a modulator connected to the infrared light source for modulating the directed infrared light source beam at a predetermined frequency.

10. The system of claim 9 in which the infrared photon detector is tuned to the said predetermined frequency.

11. The system of claim 8 in which the emitter further includes an emitter collimator about the infrared light source for directing the beam and in which the detector further includes a detector collimator about the infrared photon detector to define the field of view.

12. The system of claim 11 in which the emitter collimator and the detector collimator are angled with respect to the surface to define a finite region of intersection.

13. The system of claim 1 in which the object is diffuse and at least one of the detector and the emitter is oriented normal to the object.

14. The system of claim 1 further including a lens for the emitter and a lens for the detector to control the region.

15. The system of claim 1 further including a control system configured to operate the robot in a plurality of modes including an obstacle following mode whereby said robot travels adjacent to an obstacle.

16. The system of claim 15 whereby said obstacle following mode comprises alternating between decreasing the turning radius of the robot as a function of distance traveled such that the robot turns toward said obstacle until the obstacle is detected and decreasing the turning radius of the robot as a function of distance traveled such that the robot turns away from said obstacle until the obstacle is no longer detected.

17. The system of claim 15 in which the robot operates in obstacle following mode for a distance greater than twice the work width of the robot and less than approximately ten times the work width of the robot.

18. The system of claim 17 in which the robot operates in obstacle following mode for a distance greater than twice the work width of the robot and less than five times the work width of the robot.

19. A sensor subsystem for an autonomous robot, the sensor subsystem comprising:

at least two emitters, each for emitting a beam having a field of emission toward a surface upon which the autonomous robot travels;

at least two photon detectors, each having a field of view which intersects at least one field of emission at a region; and

a circuit in communication with the detectors to re-direct the autonomous robot when the surface is not present in at least one region.

20. The sensor subsystem of claim 19, wherein at least one of the emitters is at least partially disposed within a collimator.

21. The sensor subsystem of claim 19, wherein at least one of the emitters is at least partially disposed within a component of the autonomous robot.

22. The sensor subsystem of claim 21, wherein the component is a robot housing.

23. The sensor subsystem of claim 21, wherein the component at least partially defines the field of emission of the emitted beam.

24. The sensor subsystem of claim 21, wherein at least one of the emitters and the respective detector are angled with respect to each other and wherein at least one of the emitters and the respective detector are angled with respect to the surface upon which the autonomous robot travels.

25. The sensor subsystem of claim 19, wherein at least one of the detectors is at least partially disposed within a component of the autonomous robot.

26. The sensor subsystem of claim 25, wherein the component at least partially defines a field of view of the photon detector.

27. The sensor subsystem of claim 19, wherein at least one of the emitters is proximate an edge of the autonomous robot.

28. The sensor subsystem of claim 19, wherein at least one of the emitters is proximate a wheel of the autonomous robot.

29. The sensor subsystem of claim 19, wherein at least one of the emitters is recessed relative to a surface of the autonomous robot.

30. The sensor subsystem of claim 29, wherein the surface of the autonomous robot comprises a bottom surface.

31. The sensor subsystem of claim 19, wherein the output causes the autonomous robot to travel in a direction opposite a direction of travel of the autonomous robot prior to sensing the surface not present in at least one region.

32. The sensor subsystem of claim 19, wherein the sensor subsystem is located at a forward portion of the robot.

33. The sensor subsystem of claim 19, wherein the sensor subsystem comprises at least three emitters and at least three detectors.

34. The sensor subsystem of claim 19, further comprising at least one emitter and at least one detector for detecting a surface other than the surface upon which the autonomous robot travels.