Optical Tracking Target With Protrusion for Multi-Axis Orientation
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Solution Overview
Problem
Existing targets used in surgical and other tracking applications are ineffective in accurately indicating rotation out of the plane viewed by an image sensor, particularly for axes other than the first axis.
Innovation Solution
The use of targets with a planar surface featuring an optically detectable pattern and at least one protrusion or specular reflective region, which provide accurate orientation information about multiple axes by employing contrasting regions and geometric shapes to enhance detectability and accuracy in image analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing targets with planar surfaces and optically detectable patterns are used, then position information and orientation about the first axis (perpendicular to the planar surface) can be accurately determined, but orientation information about other axes (parallel to the planar surface) cannot be accurately provided
Solution Approach 1:
The patent extends the tracking capability from 2D planar patterns to 3D structures by adding protrusions that extend from the planar surface. These protrusions create additional geometric features visible from multiple angles, enabling the determination of orientation about axes parallel to the planar surface (second and third axes) in addition to the first axis, thus resolving the information loss about rotational orientation.
2Measurement precision
If protrusions are added to the target to provide accurate orientation information about multiple axes, then orientation detection capability is improved, but the device complexity increases
Solution Approach 1:
The patent segments the target into distinct functional components: a planar surface with an optically detectable pattern for position and first-axis orientation, and one or more protrusions extending from the planar surface for second and third axis orientation. This segmentation allows each component to serve its specific function while maintaining overall system manageability and reducing complexity compared to a completely new design.
3Measurement precision
If multiple protrusions with different extensions are used to indicate different angular ranges, then orientation tracking accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs asymmetric protrusion designs where each protrusion extends to a different extent from the planar surface. This asymmetry creates distinct geometric signatures for different angular ranges, allowing the tracking system to accurately determine orientation by identifying which protrusions are visible and their relative positions. The asymmetric design encodes angular information directly in the geometry, simplifying the detection algorithm while maintaining manufacturing feasibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The described targets enable precise determination of position and orientation about multiple axes, improving tracking accuracy and robustness against occlusions and varying orientations, thereby enhancing the effectiveness of optical tracking systems.
Implementation Method 1
a planar surface with an optically detectable pattern thereon, the optically detectable pattern providing accurate position information of the target, and accurate orientation information of the target about a first axis perpendicular to the planar surface
Implementation Method 2
The at least one protrusion may be configured to occlude a portion of the planar surface based on an orientation of the target about the second axis, and wherein a shape of occlusion of the planar surface by the protrusion identifies the orientation of the target about the second axis
Implementation Method 3
a target comprises a planar surface with an optically detectable pattern thereon, with a specular reflective region. The optically detectable pattern provides accurate position information of the target, and provides accurate orientation information of the target about a first axis perpendicular to the planar surface
Data Source
AI summary
Described are targets for use in optical tracking, as well as related methods. In some implementations, a target comprises a planar surface with an optically detectable pattern thereon, and at least one protrusion extending from the planar surface. In other implementations, a target comprises a planar surface with an optically detectable pattern thereon, with a specular reflective region. The optically detectable pattern provides accurate position information of the target, and provides accurate orientation information of the target about a first axis, but may not provide accurate orientation information of the target about other axes. The at least one protrusion or the specular reflective region provide accurate information of orientation of the target, particularly orientations about axes other than the first axis.