Management of resources for SLAM in large environments

• US 9,250,081 B2
• Filed: 11/09/2012
• Issued: 02/02/2016
• Est. Priority Date: 03/25/2005
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Gutmann, Jens-Steffen, Goel, Dhiraj, Munich, Mario E.
• Primary Examiner(s): Tran, Khoi
• Assistant Examiner(s): PECHE, JORGE O
• Application Number:
  US13/673,926
• Publication Number:
  US 20130138246A1
• Time in Patent Office: 1,180 Days
• Field of Search: 700/253, 700/245, 700/258, 701/400, 701/408, 701/409, 701/513
• US Class Current: 1/1
• CPC Class Codes: G01C 21/12 executed aboard the object being navigated; Dead reckoning
• CPC Class Codes: G01S 17/06 Systems determining position data of a target
• CPC Class Codes: G05D 1/0231 using optical position detecting means position-fixing by using electromagnetic waves other than radio waves, e.g. optical position detecting means G01S5/16
• CPC Class Codes: G05D 1/0234 using optical markers or beacons optical beacons per se G01S1/70
• 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: G05D 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30
• CPC Class Codes: G05D 1/028 using a RF signal
• CPC Class Codes: Y10S 901/01 Mobile robot
• CPC Class Codes: Y10S 901/47 Optical

Abstract

Vector Field SLAM is a method for localizing a mobile robot in an unknown environment from continuous signals such as WiFi or active beacons. Disclosed is a technique for localizing a robot in relatively large and/or disparate areas. This is achieved by using and managing more signal sources for covering the larger area. One feature analyzes the complexity of Vector Field SLAM with respect to area size and number of signals and then describe an approximation that decouples the localization map in order to keep memory and run-time requirements low. A tracking method for re-localizing the robot in the areas already mapped is also disclosed. This allows to resume the robot after is has been paused or kidnapped, such as picked up and moved by a user. Embodiments of the invention can comprise commercial low-cost products including robots for the autonomous cleaning of floors.

Claims

1. A method of managing resources for a robot, the method comprising:

performing simultaneous localization and mapping (SLAM) for the robot in a first area with a first map;

performing SLAM for the robot in a second area associated with a second map, wherein the second map is maintained independently the first map;

switching between performing SLAM with the first map or performing SLAM with the second map;

performing position estimation for the robot in a third area outside of the first area and the second area;

storing information about which one of the first area or the second area the robot was in prior to entry to the third area;

estimating a position uncertainty of the robot while operating in the third area;

remembering which one of the first area or the second area the robot was in prior to entry to the third area; and

if the position uncertainty is larger than a predetermined threshold, returning to the one of the first area or the second area from which the robot was in prior to entry to the third;

area, wherein a controller of the robot is configured to return the robot to the one of the first area or the second area.

2. The method of claim 1, further comprising:

observing a plurality of sets of one or more continuous signals including the first set and the second set, wherein each of the plurality of observed sets is associated with a separate map;

determining that a largest observed signal strength of the plurality of observed sets is larger in magnitude than a signal strength of a set currently being used for performing SLAM; and

switching to performing SLAM with the set with the largest observed signal strength.

3. The method of claim 2, wherein the first set of one or more continuous signals and the second set of one or more continuous signals comprise reflections of spots of infrared light.

4. The method of claim 3, further comprising distinguishing among the different reflections of spots of infrared light based on frequency.

5. The method of claim 1, further comprising:

observing a plurality of sets of one or more continuous signals including the first set and the second set, wherein each of the plurality of observed sets is associated with a separate map;

determining that a largest observed signal strength of the plurality of observed sets is at least a predetermined factor larger in magnitude than a signal strength of a set currently being used for performing SLAM; and

switching to performing SLAM with the set with the largest observed signal strength.

6. The method of claim 5, wherein the predetermined factor is a factor of 2.

7. The method of claim 1, wherein the robot comprises an autonomous robotic cleaner, the method further comprising performing SLAM while cleaning a surface.

8. The method of claim 1, further comprising performing SLAM in the first area and the second area using infrared spots and performing SLAM in the third area using dead reckoning.

9. The method of claim 8, wherein dead reckoning is performed using odometry and a gyroscope.

10. The method of claim 1, further comprising:

estimating a position uncertainty of the robot while operating in the third area; and

if the position uncertainty is larger than a predetermined threshold, returning to at least one of the first area or the second area.

11. An apparatus comprising:

a robot;

a controller of the robot configured to;

perform simultaneous localization and mapping (SLAM) for the robot in a first area with a first map;

perform SLAM for the robot in a second area with a second map, wherein the second map is maintained independently the first map;

switch between performing SLAM with the first map or performing SLAM with the second map;

perform position estimation for the robot in a third area outside of the first area and the second area;

store information about which one of the first area or the second area the robot was in prior to entry to the third area;

estimate a position uncertainty of the robot while operating in the third area;

remember which one of the first area or the second area the robot was in prior to entry to the third area; and

if the position uncertainty is larger than a predetermined threshold, return the robot to the one of the first area or the second area from which the robot was in prior to entry to the third area.

12. The apparatus of claim 11, wherein the controller is further configured to:

observe a plurality of sets of one or more continuous signals including the first set and the second set, wherein each of the plurality of observed sets is associated with a separate map;

determine that a largest observed signal strength of the plurality of observed sets is larger in magnitude than a signal strength of a set currently being used for performing SLAM; and

switch to performing SLAM with the set with the largest observed signal strength.

13. The apparatus of claim 12, wherein the first set of one or more continuous signals and the second set of one or more continuous signals comprise reflections of spots of infrared light.

14. The apparatus of claim 13, wherein the controller is further configured to distinguish among the different reflections of spots of infrared light based on frequency.

15. The apparatus of claim 11, wherein the controller is further configured to:

observe a plurality of sets of one or more continuous signals including the first set and the second set, wherein each of the plurality of observed sets is associated with a separate map;

determine that a largest observed signal strength of the plurality of observed sets is at least a predetermined factor larger in magnitude than a signal strength of a set currently being used for performing SLAM; and

switch to performing SLAM with the set with the largest observed signal strength.

16. The apparatus of claim 15, wherein the predetermined factor is a factor of 2.

17. The apparatus of claim 11, wherein the robot comprises an autonomous robotic cleaner, wherein the controller is further configured to perform SLAM while the robot is cleaning a surface.

18. The apparatus of claim 11, wherein the controller is further configured to perform SLAM in the first area and the second area using infrared spots and to perform SLAM in the third area using dead reckoning.

19. The apparatus of claim 18, wherein dead reckoning is performed using odometry and a gyroscope.

20. The apparatus of claim 11, wherein the controller is further configured to:

estimate a position uncertainty of the robot while operating in the third area; and

if the position uncertainty is larger than a predetermined threshold, return to at least one of the first area or the second area.

21. An apparatus comprising:

a robot; and

a means for performing simultaneous localization and mapping (SLAM) for the robot in a first area with a first map, performing SLAM for the robot in a second area associated with a second map, wherein the second map is maintained independently of the first map, switching between performing SLAM with the first map or performing SLAM with the second map, performing position estimation for the robot in a third area outside of the first area and the second area, storing information about which one of the first area or the second area the robot was in prior to entry to the third area, estimating a position uncertainty of the robot while operating in the third area, remembering which one of the first area or the second area the robot was in prior to entry to the third area, and if the position uncertainty is larger than a redetermined threshold, returning to the one of the first area or the second area from which the robot was in prior to entry to the third area.

22. The apparatus of claim 21, wherein the apparatus further comprises:

observing a plurality of sets of one or more continuous signals including the first set and the second set, wherein each of the plurality of observed sets is associated with a separate map;

determining that a largest observed signal strength of the plurality of observed sets is larger in magnitude than a signal strength of a set currently being used for performing SLAM; and

switching to performing SLAM with the set with the largest observed signal strength;

wherein the first set of one or more continuous signals and the second set of one or more continuous signals comprise reflections of spots of infrared light.

23. The apparatus of claim 22, further comprising means for distinguishing among the different reflections of spots of infrared light based on frequency.

24. The apparatus of claim 21, wherein the robot comprises an autonomous robotic cleaner, the apparatus further comprising means for performing SLAM while cleaning a surface.