Mobile robot navigation employing ceiling light fixtures
AssigneeTransitions Research Corporation
InventorsJohn M. Evans, Jr., Carl F. R. Weiman, Steven J. King
Life of this patent
Estimating the term…
Abstract
Apparatus and method which provides for the determination of a vehicle's orientation and position in an environment, such as a hallway, from an image of ceiling lights. A mobile robot 10 includes a camera 12 that is pitched up obliquely at an intermediate angle between a horizon and a zenith. The camera views a ceiling having one or more ceiling lights 16 which may be of rectangular shape and which are preferably aligned with an axis of the hallway. In that the lights present a pattern or alignment which is substantially parallel to or perpendicular to a long axis of the hallway the pattern is detected and processed to derive robot navigation information therefrom.
Claims24
Navigation apparatus for generating navigation related information for a vehicle, comprising:
- means for obtaining a two-dimensional image of a surface which overlies a vehicle or a projected path of the vehicle, the two-dimensional image being comprised of a plurality of image pixels, the surface being a horizontal surface disposed parallel to a plane upon which the vehicle moves, the surface having one or more sources of illumination disposed upon or within the surface;
- means, coupled to said obtaining means, for detecting a location within the image of the one of more sources, said detecting means comprising means for processing the two-dimensional image to detect pixels having a brightness value that exceeds a threshold brightness value, the detected pixels including pixels associated with an image of an edge of the one or more sources of illumination;
- and
- means, coupled to said detecting means for generating, from the detected source location or locations, at least vehicle orientation information relative to the edge of the one or more sources of illumination.
Navigation apparatus as set forth in claim 7, wherein said generating means comprises means, coupled to said processing means, for projecting within the image a line from the pixels which correspond to each of the substantially parallel edges of the source, the intersection of the projected lines locating a position of a horizon line within the two-dimensional image.
Navigation apparatus for generating navigation related information for a mobile robot, comprising:
- means for imaging at least a portion of a ceiling disposed over a forward path of a mobile robot, said imaging means generating a two-dimensional image comprised of a plurality of image pixels;
- means for locating, within the imaged portion of the ceiling, at least one edge of at least one ceiling light which is disposed within the imaged portion of the ceiling, the at least one ceiling light providing illumination, said locating means comprising means having an input coupled to the imaging means for processing the two-dimensional image to detect pixels having a brightness value that exceeds a threshold brightness value, the detected pixels including those pixels associated with the image of the ceiling light;
- and
- means for generating a reference axis of robot motion relative to the located boundary of the ceiling light;
- and
- means for determining at least an orientation angle of the robot relative to the reference axis of robot motion.
A method of providing navigation related information for a mobile robot, comprising the steps of:
- obtaining at least one two-dimensional image of a ceiling having one or more visual illuminated ceiling lights, the ceiling overlying at least the projected path of the robot, the two-dimensional image being comprised of a plurality of image pixels;
- locating within the ceiling image the one or more illuminated ceiling lights, the step of location including a step of examining pixels from the two-dimensional image to detect pixels having a value that exceeds a threshold value, the threshold value being selected to differentiate between a pixel associated with the illuminated ceiling light and a pixel not associated with the illuminated ceiling light;
- detecting a boundary of at least one of the illuminated ceiling lights;
- generating at least one reference line relative to the detected boundary;
- and
- determining at least an angular orientation of the robot relative to the reference line.
A method of providing navigation information for a vehicle, comprising the steps of:
- imaging with a two-dimensional image generating means a surface which is disposed above at least the projected forward path of the vehicle, the surface having a height zo above the vehicle, the surface including one or more sources of illumination;
- detecting within a generated two-dimensional image of the surface at least two opposing edges of one of the sources of illumination, the step of detecting including a step of examining image pixels from the two-dimensional image to detect those pixels having a value that exceeds a threshold value, the threshold value being selected to differentiate between a pixel associated with a source of illumination and a pixel not associated with a source of illumination;
- detecting at least two opposing edges of a second one of the sources of illumination;
- determining a centrally located point of each of the sources of illumination, a line passing through each of the centrally located points defining an axis of alignment, the axis of alignment intersecting a horizon line associated with the two-dimensional image;
- projecting the axis of alignment unto the two-dimensional image to obtain a slope m;
- determining a pitch (Pch) component and a yaw (Yaw) component of vehicle orientation relative to the axis of alignment;
- and
- determining a lateral displacement xO of the vehicle from the axis of alignment in accordance with the equation:
- ##EQU11##
Dependencies are inferred from the claim text.