Compact 6D Positioning via Shadow Mask and Single Sensor
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Solution Overview
Problem
Existing devices for determining the position and orientation of two rigid bodies in relation to each other are often bulky, costly, and not suitable for applications with limited space, such as minimal invasive surgery, where high precision is required.
Innovation Solution
An apparatus comprising a punctual light source, an image sensor, a shadow mask, and a mechanical constraint, which calculates angles by evaluating a shadow image generated by light passing through the shadow mask, allowing for precise determination of position and orientation while minimizing space and components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional positioning devices such as 6D cameras or stereo cameras are used to measure position and orientation, then measurement precision is improved, but device complexity and volume increase
Solution Approach 1:
The patent extracts only the essential measurement function from complex 6D camera systems by using a single image sensor to capture shadow images. Instead of using multiple cameras or complex sensor arrays, the invention isolates the core measurement capability to a minimal set of components: one light source, one shadow mask, and one image sensor, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent uses a shadow mask to create a shadow image that copies the geometric information of the rigid body's position and orientation. The shadow image serves as a simplified representation that contains all necessary measurement data, allowing the computation unit to calculate position and orientation without needing complex multi-camera systems.
2Measurement precision
If conventional positioning devices are used to achieve high precision measurement, then measurement precision is improved, but the device becomes bulky and difficult to use in limited space
Solution Approach 1:
The patent removes unnecessary components from conventional positioning devices, retaining only the essential elements needed for measurement. By using a single light source, shadow mask, and image sensor instead of bulky multi-camera systems, the device volume is dramatically reduced while maintaining the ability to measure position and orientation with high precision.
Solution Approach 2:
The patent merges multiple functions into a compact arrangement where the light source, shadow mask, and image sensor work together in a unified system. The shadow mask serves both as a geometric reference and as the object being imaged, eliminating the need for separate reference structures and reducing overall device volume.
3Measurement precision
If conventional positioning devices are used to achieve precise measurement, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent replaces expensive, complex positioning devices with inexpensive, simple components. The shadow mask can be a simple printed or etched plate, the light source can be a standard LED, and the image sensor can be a conventional camera sensor. This approach achieves high measurement precision using components that are much cheaper than industrial 6D cameras or stereo camera systems.
Solution Approach 2:
The patent uses a shadow image as a cheap copy of the rigid body's spatial information. Instead of using expensive specialized sensors, the system creates a two-dimensional shadow representation that can be captured by standard image sensors and processed computationally, significantly reducing hardware costs while maintaining measurement precision.
4Volume of moving object
If the number of degrees of freedom is reduced to enable compact arrangement, then device volume is reduced, but measurement capability may be limited
Solution Approach 1:
The patent uses the shadow image plane as an additional dimension for encoding spatial information. By projecting the three-dimensional rigid body onto a two-dimensional shadow plane, the system captures position and orientation data in a compact form. The computation unit then reconstructs the full six-degree-of-freedom information from these two-dimensional shadow measurements, maintaining measurement precision while enabling a compact device arrangement.
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
Enables efficient and precise measurement of the position and orientation of two rigid bodies in a compact arrangement, suitable for applications like minimal invasive surgery, by reducing degrees of freedom and using a shadow mask to generate a unique shadow image for calculation.
Implementation Method 1
a shadow mask mounted stationary in relation to either the first rigid body or the second rigid body and arranged in the field of light propagated from the light source between the light source and the image sensor
Data Source
Figure 1
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Figure 3~4
AI summary
An apparatus (4) for determining a position and orientation of a first rigid body (1) and a second rigid body (2) in relation to each other. The apparatus comprises: an at least essentially punctual light source (13) mounted stationary in relation to the first rigid body (1); an image sensor (15) mounted stationary in relation to either the first rigid body (1) or the second rigid body (2) and positioned in a field of light propagated by the light source (13); a shadow mask (11) mounted stationary in relation to either the first rigid body (1) or the second rigid body (2) and arranged in the field of light propagated from the light source (13) between the light source (13) and the image sensor (15); and a computation unit configured to calculate at least one angle (α, β) by evaluating a shadow image (12) generated by light propagated by the light source (13) which passes the shadow mask (13) and which is detected by the image sensor (15). The apparatus (4) further comprises a mechanical constraint (3) mounted to a first connection spot of the first rigid body (1) and to a second connection spot of the second rigid body (2), wherein the mechanical constraint defines a fixed distance between the first connection spot of the first rigid body (1) and the second connection spot of the second rigid body (2), is stationary in relation to one of the first rigid body (1) or the second rigid body (2), and is variably inclinable in relation to the other one of the first rigid body (1) and the second rigid body (2).