Patent ID: 11927438
Assignee: THE BOEING COMPANY
Field: Computer technology (Electrical engineering)
Classification: CPC G  B | IPC B  G

Claim 7:
8. A method for calibrating poses of fiducial markers relative to a workpiece, the method comprising:
receiving, by a processor and from one or more cameras, a set of images of the fiducial markers, wherein each image is acquired by the one or more cameras at a different camera pose of a plurality of camera poses, wherein the fiducial markers comprise (i) one or more first fiducial markers coupled at one or more unknown fixed locations on the workpiece and (ii) a plurality of calibration fiducial markers disposed at a plurality of known locations on the workpiece in a temporary manner, wherein each first fiducial marker displays a first type of machine-readable label and each calibration fiducial marker displays a second type of machine-readable label, and wherein the plurality of known locations are based on a three-dimensional (3D) model of the workpiece;
detecting, in the set of images, the one or more first fiducial markers coupled at the one or more unknown fixed locations on the workpiece based on the first type of machine-readable label and the plurality of calibration fiducial markers disposed at the plurality of known locations on the work piece based on the second type of machine-readable label;
estimating, by the processor, poses of the fiducial markers based on detecting the one or more first fiducial markers and the plurality of calibration fiducial markers, wherein for each image of the set of images, a pose of each fiducial marker that is visible in the image is estimated relative to the one or more cameras;
formulating, by the processor, a pose graph comprising (i) nodes for the set of images and for the fiducial markers, (ii) the poses estimated for the fiducial markers, (iii) the plurality of calibration fiducial markers as landmarks with known poses, and (iv) a set of constraints between the set of images and the plurality of calibration fiducial markers; and
solving, by the processor, the pose graph to determine poses of the one or more first fiducial markers relative to the work piece that satisfy the set of constraints.