Polychrome Cube Corner Reflectors for Wide-Angle Helmet Posture Detection
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Solution Overview
Problem
Existing optical systems for detecting the orientation of a helmet, such as those used in aircraft pilots, face limitations in angular field detection due to the geometric constraints of cube corner reflectors, which restrict the precision and range of measurement, especially under varying light conditions and source distances.
Innovation Solution
The system employs cube corner reflectors with a polychrome entry face, where each colored zone has a specific spectral filter and marking, allowing for a larger angular field coverage by analyzing the colored contours projected on a color mosaic sensor, and uses a coding method to discriminate between reflectors and their reflections, ensuring measurement accuracy across a wide range without sensitivity to light power or color variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a cube corner reflector with a mask is used, then the device complexity is reduced and depth of field is increased, but the angular field of detection is limited
Solution Approach 1:
The patent applies color changes by dividing the entry face of the cube corner reflector into multiple colored zones (red, green, blue filters), each corresponding to a different spatial region. This allows the system to encode angular position information through color detection, significantly expanding the angular field of detection while maintaining device simplicity
Solution Approach 2:
The entry face is segmented into multiple colored zones with different spectral transmission characteristics. Each zone independently detects light from specific angular ranges, allowing the system to measure orientation across a wide angular field by analyzing which colored zones are illuminated
2Adaptability or versatility
If multiple cube corner reflectors are combined to increase angular field, then the angular field of detection is expanded, but the difficulty of discriminating reflections increases
Solution Approach 1:
Each cube corner reflector is assigned a unique color pattern or spectral signature through its colored zones. This allows the detection system to easily discriminate between reflections from different reflectors by analyzing the color composition of the returned light, eliminating the difficulty of distinguishing between multiple reflectors
Solution Approach 2:
Different regions of the entry face have different spectral transmission properties (red, green, blue zones). This local differentiation allows each zone to carry independent information about the reflector's orientation and position, enabling precise measurement while simplifying the discrimination of multiple reflectors
3Adaptability or versatility
If a polychrome entry face with colored zones is used, then the angular field of detection is increased, but the manufacturing precision requirements increase
Solution Approach 1:
The patent uses broad spectral bands for the colored filters (red, green, blue) rather than narrow wavelengths, which makes the system more tolerant to variations in colored zone positioning during manufacturing. The color detection approach naturally accommodates reasonable manufacturing tolerances while maintaining accurate angular measurement
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
This approach significantly increases the angular field of detection to π/2 steradian, ensuring precise orientation measurement over a large range while maintaining robustness against light and color variations, thus enhancing the precision and reliability of helmet posture detection systems.
Implementation Method 1
each colored zone comprising a filter in spectral transmission, each filter transmitting only a predetermined spectral band different from those of the other filters in spectral transmission
Implementation Method 2
cube corner reflector offers a theoretical angular field of solid angle π/2 steradian
Implementation Method 3
three orthogonal triangular reflective faces two by two POQ, QOR and POR
Data Source
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AI summary
The general field of the invention is that of optical posture detection systems for a moving object in space. The system according to the invention comprises an optical assembly (DCCC) including several optical cube corners (Re1, Re2, Re3, Re4, Re5, Re6) arranged on the moving object. The entrance face of the cube corners is divided into three distinct colored zones, each containing a spectral transmission filter that transmits only a predetermined spectral band, different from those of the other filters. Each side of said colored zones has a specific marking allowing identification of said side. The spectrum of the emission source has a spectral width equal to the sum of the spectral bands of said filters.The associated fixed electro-optical orientation device includes at least one color matrix sensor and the image analysis means include means for determining shapes and geometric characteristics in the images received by the color matrix sensor(s).