Methods and apparatus for position estimation using reflected light sources
The invention is generally related to the estimation of position and orientation of an object with respect to a local or a global coordinate system using reflected light sources. A typical application of the method and apparatus includes estimation and tracking of the position of a mobile autonomous robot. Other applications include estimation and tracking of an object for position-aware, ubiquitous devices. Additional applications include tracking of the positions of people or pets in an indoor environment. The methods and apparatus comprise one or more optical emitters, one or more optical sensors, signal processing circuitry, and signal processing methods to determine the position and orientation of at least one of the optical sensors based at least in part on the detection of the signal of one or more emitted light sources reflected from a surface.
1. A mobile robot system, the system comprising:
a mobile robot;
a modulator;
a first illumination projector coupled to the modulator, wherein the modulator is configured to modulate light from the first illumination projector, wherein the first illumination projector is configured to project modulated light, whereby at least one projected illumination spot is projected onto at least one non-vertical surface positioned above the first illumination projector when the first illumination projector is positioned for operation with the mobile robot;
a detector configured to detect the at least one projected illumination spot based at least in part on the modulation; and
a data processing unit configured to:
determine a direction of the detected at least one projected illumination spot with respect to a first reference point, and determine a location of the mobile robot based at least in part on the determined direction, wherein the detector is configured to detect the at least one projected illumination spot without having a line of sight view of the first illumination projector.
2. The mobile robot system of claim 1 , wherein:
the first illumination projector includes a first plurality of light emitters configured to project at least two projected illumination spots, wherein the modulator is configured to cause light projected to form a first of the two projected illumination spots to be modulated differently than light projected to form a second of the two projected illumination spots; and
the mobile robot system is configured to distinguish between the first projected illumination spot and the second projected illumination spot based on the respective modulations used to form the first projected illumination spot and the second projected illumination spot.
3. The mobile robot system of claim 1 , wherein the first illumination projector includes a first plurality of light emitters configured to project at least two projected illumination spots, wherein the modulator is configured to:
cause a first of the two projected illumination spots to have a first light pattern; and
cause a second of the two projected illumination spots to have a second light pattern, wherein the second light pattern is different than the first light pattern.
4. The mobile robot system of claim 1 , wherein determining the location further comprises determining a pose of the mobile robot and the first illumination projector comprises an infrared illumination projector.
5. The mobile robot system of claim 1 , wherein the detector includes a sensor, a lens, and a filter, wherein the filter is configured to narrow a range of light received by the sensor to correspond to the light projected by the first illumination projector wherein the first illumination projector stays at one location while the mobile robot moves about an environment.
6. The mobile robot system of claim 1 , further comprising a second illumination projector configured to project light with a different modulation than the first illumination projector, wherein the first illumination projector is housed separately from the second illumination projector, and wherein the mobile robot system is configured to:
associate the modulation associated with the first illumination projector with a first room and the modulation associated with the second illumination projector with a second room; and
to build a topological map including connectivity of the first room and the second room.
7. A mobile robot system, the system comprising:
a mobile robot;
a modulator;
a first illumination projector coupled to the modulator, wherein the modulator is configured to modulate light from the first illumination projector, wherein the first illumination projector is configured to project modulated light from a location different than that of the mobile robot, whereby at least one projected illumination spot is projected onto at least one non-vertical surface positioned above the first illumination projector when the first illumination projector is positioned for operation with the mobile robot, wherein the first illumination projector stays at one location while the mobile robot moves about an environment;
a detector configured to detect the at least one projected illumination spot based at least in part on the modulation; and
a data processing unit configured to:
determine a direction of the detected at least one projected illumination spot with respect to a first reference point, and determine a location of the mobile robot based at least in part on the determined direction.
8. The mobile robot system of claim 7 , wherein the first illumination projector includes a first plurality of light emitters configured to project at least two projected illumination spots, wherein the modulator is configured to cause light projected to form a first of the two projected illumination spots to be modulated differently than light projected to form a second of the two projected illumination spots; and
the mobile robot system is configured to distinguish between the first projected illumination spot and the second projected illumination spot based on the respective modulations used to form the first projected illumination spot and the second projected illumination spot.
9. The mobile robot system of claim 7 , wherein the data processing unit is configured to determine a pose of the mobile robot, and wherein the first illumination projector comprises an infrared illumination projector.
10. The mobile robot system of claim 7 , wherein the detector includes a sensor, a lens, and a filter, wherein the filter is configured to narrow a range of light received by the sensor to correspond to the light projected by the first illumination projector.
11. The mobile robot system of claim 7 , further comprising a second illumination projector configured to project light with a different modulation than the first illumination projector, wherein the first illumination projector is housed separately from the second illumination projector, and wherein the mobile robot system is configured to:
associate the modulation associated with the first illumination projector with a first room and the modulation associated with the second illumination projector with a second room; and
to build a topological map including connectivity of the first room and the second room.
12. A mobile robot system, the system comprising:
a mobile robot;
a modulator;
at least a first illumination projector coupled to the modulator, wherein the modulator is configured to modulate light from the at least first illumination projector, wherein the at least first illumination projector is configured to project first and second projected illumination spots onto different locations from one another on at least one non-vertical surface when the at least first illumination projector is positioned for operation with the mobile robot, wherein the first projected illumination spot has a first optical signature and the second projected illumination spot has a second optical signature;
a detector configured to detect the first and second projected illumination spots based at least in part on the first and second signatures; and
a data processing unit configured to determine a location of the mobile robot based at least in part on the detection of:
the first projected illumination spot, and
the second projected illumination spot.
13. The mobile robot system of claim 12 , wherein the first signature is in the form of a first light pattern and the second signature is in the form of a second light pattern.
14. The mobile robot system of claim 12 , wherein the data processing unit is further configured to determine a pose of the mobile robot.
15. The mobile robot system of claim 12 , wherein the first illumination projector comprises an infrared illumination projector.
16. The mobile robot system of claim 12 , wherein the detector includes a sensor, a lens, and a filter, wherein the filter is configured to narrow a range of light received by the sensor to correspond to the light projected by the first illumination projector.
17. The mobile robot system of claim 12 , wherein the mobile robot system is configured to build a topological map including connectivity of a first room and a second room.
18. A mobile robot system including a mobile robot, the system comprising:
an illumination projector that stays at one location while the mobile robot moves about an environment, the illumination projector including:
a first spot projector including a first non-visible light source and at least one lens configured to project a first spot projection having a first signature to a first location on a non-vertical ceiling surface, and
a second spot projector including a second non-visible light source and at least one lens configured to project a second spot projection having a second signature to a second location separated from the first location on the non-vertical ceiling surface; and
a detector mounted atop the mobile robot and directed toward the non-vertical ceiling surface, the detector configured to simultaneously detect both the first and second spot projections based at least in part on the first and second signatures; and
a data processing unit configured to:
record successive mobile robot poses defining a global coordinate system in which the mobile robot's current pose can be determined, and
determine a current pose of the mobile robot based at least in part on the detection of the first and second spot projections having the first and second signatures.
19. The mobile robot system of claim 18 ,
wherein the data processing unit is further configured to determine a direction of the first and second spot projections having the first and second signatures with respect to a first reference point, and determine a location of the mobile robot based at least in part on the determined direction, wherein the detector is configured to detect the first and second spot projections having the first and second signatures without having a line of sight view of the first illumination projector.
20. The mobile robot system of claim 18 ,
wherein the detector includes a sensor, a lens, and a filter, wherein the filter is configured to narrow a range of light received by the sensor to exclude at least a portion of ambient light and to correspond to the light projected by the illumination projector.
21. The mobile robot system of claim 18 ,
wherein the first optical signature comprises a first identifier and the second optical signature comprises a second identifier different from the first identifier.