| CPC G06F 3/012 (2013.01) [G06F 3/0346 (2013.01); G06T 7/20 (2013.01); G06T 7/70 (2017.01); G06T 2207/30201 (2013.01); G06T 2207/30208 (2013.01)] | 16 Claims |
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1. A head tracking system for a head worn display (HWD), comprising:
at least one platform inertial measurement unit (pIMU) configured to be fixed to a mobile platform, the mobile platform associated with a platform reference frame, the at least one pIMU configured to provide, at substantially a first rate, platform-referenced position and orientation (pose) data corresponding to the mobile platform and relative to the platform reference frame;
at least one head inertial measurement unit (hIMU) configured to be fixed to a head of a wearer of the HWD, the at least one hIMU configured to provide, at substantially the first rate, head-referenced pose data corresponding to the head and relative to a head reference frame;
an optical tracker configured to be mounted to one of the mobile platform or the head, the optical tracker comprising:
at least one data storage element configured for storage of:
processor-executable encoded instructions;
and
constellation data associated with one or more fiducial markers, the constellation data associated with each fiducial marker comprising:
a unique encoded identifier;
and
location data associated with a position and orientation of the fiducial marker relative to a three-dimensional (3D) reference frame;
at least one camera configured to capture image data relative to a two-dimensional (2D) reference frame;
at least one processor operatively coupled to the camera, the processor configurable by the processor-executable encoded instructions to:
identify, at least one fiducial marker associated with a marker location relative to the image data;
and
based on one or more of the location data and the marker location corresponding to each identified fiducial marker, determine:
an initial optical pose of the camera relative to the 3D reference frame;
a refined optical pose of the camera relative to the 3D reference frame and based on the initial optical pose;
and
an optical pose error model corresponding to the refined optical pose;
at least one georeferenced aiding device configured to provide, at a second rate lower than the first rate, georeferenced pose data relative to an earth-centered reference frame;
and
at least one controller in data communication with the at least one pIMU, the at least one hIMU, the aiding device, and the optical tracker, the controller including at least one processor configured to:
determine, at substantially the second rate:
1) An output head pose solution based on the platform-referenced pose data, the head-reference pose data, and the georeferenced pose data, the output head pose relative to the earth-centered reference frame;
and
2) an output error bound corresponding to the output head pose solution;
and
determine, at substantially the first rate:
1) An update head pose solution based on one or more of a) the most recent output head pose solution and b) a Kalman filter propagation of the platform-referenced pose data, the head-referenced pose data, and the refined optical pose, the update head pose relative to the 3D reference frame;
and
2) an update error bound associated with the update head pose solution.
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