	US 12,347,139 B2
	High-confidence optical head pose correspondence mapping with multiple lower-density markers for high-integrity headtracking on a headworn display (HWD)
Christopher M. Boggs, Gainesville, VA (US); William T. Kirchner, Ashburn, VA (US); Gavin P. Haentjens, Arlington, VA (US); Kurt I. Jaeger, Catlett, VA (US); and Brandon E. Wilson, Portland, OR (US)
Assigned to Rockwell Collins, Inc., Cedar Rapids, IA (US)
Filed by Rockwell Collins, Inc., Cedar Rapids, IA (US)
Filed on Aug. 25, 2022, as Appl. No. 17/895,853.
Application 17/895,853 is a continuation in part of application No. 17/685,032, filed on Mar. 2, 2022.
Application 17/685,032 is a continuation in part of application No. 17/573,283, filed on Jan. 11, 2022, granted, now 12,136,234.
Prior Publication US 2023/0222689 A1, Jul. 13, 2023
Int. Cl. G06T 7/70 (2017.01); G06F 3/01 (2006.01); G06T 7/73 (2017.01)

CPC G06T 7/74 (2017.01) [G06F 3/012 (2013.01); G06T 2207/30196 (2013.01); G06T 2207/30204 (2013.01)]

19 Claims

1. A head tracking system for a head worn display (HWD), comprising:

at least one camera configured to capture two-dimensional (2D) image data of an environment associated with a mobile platform and with a wearer of the HWD, the 2D image data associated with an image reference frame;

at least one constellation of three or more medium-density fiducials disposed within the environment, each medium-density fiducial corresponding to a unique encoded identifier;

at least one low-density fiducial disposed within the environment, each low-density fiducial sharing a common encoded identifier;

at least one memory configured for storing:

processor-executable instructions;

and

constellation data comprising:

a known position and orientation (pose) of each medium-density fiducial and each low-density fiducial relative to a three-dimensional (3D) reference frame;

and

a marker geometry associated with at least one of a position and an orientation of each medium-density fiducial and each low-density fiducial relative to each other medium-density fiducial and low-density fiducial in a marker reference frame;

and

at least one processor in data communication with the at least one camera and the memory, the processor configurable by the processor-executable instructions to:

receive the 2D image data from the at least one camera;

detect at least one of a medium-density fiducial or a low-density fiducial within the image data, each detected medium-density and low-density fiducial associated with a pixel location relative to the image data;

determine, by comparing the at least one detected medium-density or low-density fiducial to the constellation data, (1) at least one initial estimate of a head pose of the wearer relative to the 3D reference frame and (2) an initial error bound corresponding to the at least one initial head pose estimate based on:

the unique encoded identifiers of the detected medium-density fiducials;

and

the marker geometry of the detected medium-density and low-density fiducials;

determine, based on the comparing, if one or more feasible correspondence ambiguities exist between the image data and the constellation data, each feasible correspondence ambiguity not associated with the initial head pose estimate;

and

if no feasible correspondence ambiguities are found, outputting the initial head pose estimate and the initial error bound as a high-integrity head pose solution and a corresponding high confidence error bound.