Systems and methods for controlling a density of visual landmarks in a visual simultaneous localization and mapping system

• US 7,145,478 B2
• Filed: 12/17/2003
• Issued: 12/05/2006
• Est. Priority Date: 12/17/2002
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: Evolution Robotics Inc. (iRobot Corporation)
• Inventors: Di Bernardo, Enrico, Pirjanian, Paolo, Karlsson, L. Niklas, Goncalves, Luis Filipe Domingues
• Primary Examiner(s): Swarthout, Brent A.
• Application Number:
  US10/739,394
• Publication Number:
  US 20040167716A1
• Time in Patent Office: 1,084 Days
• Field of Search: 340/988, 340/995.1, 340/995.14, 340/995.17, 340/995.18, 340/995.24, 340/995.27, 180/168, 901/1, 901/50, 348/119, 342/457, 318/568.12, 318/587, 318/568.11, 318/568.16, 701/23, 701/24, 701/25, 701/26, 701/28, 701/301, 701/208, 701/211, 700/245, 700/145, 700/165, 700/169, 700/179, 700/205, 700/250, 700/253, 700/259, 700/258, 700/247, 700/256
• US Class Current: 340/995.1
• CPC Class Codes: G01C 21/12 executed aboard the object being navigated; Dead reckoning
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• 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 1/024 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 1/0246 using a video camera in combination with image processing means
• CPC Class Codes: G05D 1/0248 in combination with a laser lasers per se H01S
• 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 1/0278 using satellite positioning signals, e.g. GPS
• CPC Class Codes: G06T 2207/30204 Marker
• CPC Class Codes: G06T 7/55 from multiple images
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80
• CPC Class Codes: G06T 7/74 involving reference images or patches
• CPC Class Codes: Y10S 901/01 Mobile robot
• CPC Class Codes: Y10S 901/46 Sensing device
• CPC Class Codes: Y10S 901/47 Optical
• CPC Class Codes: Y10S 901/50 Miscellaneous

Abstract

The invention is related to methods and apparatus that use a visual sensor and dead reckoning sensors to process Simultaneous Localization and Mapping (SLAM). These techniques can be used in robot navigation. Advantageously, such visual techniques can be used to autonomously generate and update a map. Unlike with laser rangefinders, the visual techniques are economically practical in a wide range of applications and can be used in relatively dynamic environments, such as environments in which people move. One embodiment further advantageously uses multiple particles to maintain multiple hypotheses with respect to localization and mapping. Further advantageously, one embodiment maintains the particles in a relatively computationally-efficient manner, thereby permitting the SLAM processes to be performed in software using relatively inexpensive microprocessor-based computer systems.

Claims

1. A method for managing content of a landmark database in a Visual Simultaneous Localization and Mapping System (VSLAM) for a mobile device, the method comprising:

visually obtaining a measurement of a landmark;

analyzing a quality of the measurement, where the quality of the measurement provides an indication of whether the measurement is an outlier;

storing an indication when the measurement has been identified as an outlier; and

removing a landmark from the map when the measurements of the landmark are repeatedly identified as outliers.

2. The method as defined in claim 1, wherein storing the indication further comprises updating a count of how many times the measurement has been identified as an outlier.

3. The method as defined in claim 1, wherein storing the indication further comprises updating a first count of how many times the landmark has been measured and a second count of how many times the measurements have been identified as outliers.

4. The method as defined in claim 1, wherein storing the indication further comprises updating a count of how many consecutive times the measurement has been identified as an outlier.

5. The method as defined in claim 1, wherein a measurement is identified as an outlier at least partly when a visual measurement suggests a pose that is inconsistent with a pose that is estimated by a large proportion of particles.

6. The method as defined in claim 1, wherein a measurement is identified as an outlier at least partly when a difference between a pose estimated by a visual measurement and the pose estimated by a Simultaneous Localization and Mapping System (SLAM) exceeds a predetermined threshold.

7. The method as defined in claim 1, wherein a measurement is identified as an outlier at least partly in response to a calculation of projection error.

8. The method as defined in claim 1, wherein a measurement is identified as an outlier at least partly in response to a measurement of a slope of a floor.

9. The method as defined in claim 1, wherein a measurement is identified as an outlier at least partly in response to a number of matching features common to an image and to a landmark.

10. A computer program embodied in a tangible medium for managing content of a landmark database in Visual Simultaneous Localization and Mapping System (VSLAM) for a mobile device, the computer program comprising:

a module with instructions configured to visually obtain a measurement of a landmark;

a module with instructions configured to analyze a quality of the measurement, where the quality of the measurement provides an indication of whether the measurement is an outlier;

a module with instructions configured to store an indication when the measurement has been identified as an outlier; and

a module with instructions configured to remove a landmark from the map when the measurements of the landmark are repeatedly identified as outliers.

11. The computer program as defined in claim 10, wherein the module with instructions configured to store the indication further comprises instructions configured to update a count of how many times the measurement has been identified as an outlier.

12. The computer program as defined in claim 10, wherein the module with instructions configured to store the indication further comprises instructions configured to update a first count of how many times the landmark has been measured and a second count of how many times the measurements have been identified as outliers.