Multi-Wavelength Object Sensing With Orthogonal LED Modulation
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Solution Overview
Problem
Existing object identification apparatuses face challenges in acquiring measurement data at multiple wavelengths for identifying various obstacles, require complex light emission and reception systems, are bulky due to multiple light receiving elements, and struggle with low light environments and varying solar spectra, leading to reduced accuracy and increased costs.
Innovation Solution
An object identification apparatus using a control unit that synchronizes multiple light emitting elements with a pulse modulation pattern defined by an orthogonal matrix, allowing simultaneous emission and separation of wavelength components using one light receiving element, ensuring longer light emission time and reducing device size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light receiving elements are used to detect multiple wavelengths simultaneously, then measurement precision is improved, but device complexity and size increase
Solution Approach 1:
The patent applies periodic action by modulating multiple light emitting elements with orthogonal modulation patterns (e.g., sine and cosine functions) at different frequencies. This allows a single light receiving element to detect multiple wavelength components simultaneously through frequency-domain separation, eliminating the need for multiple light receiving elements while maintaining measurement precision
Solution Approach 2:
The patent replaces the mechanical/optical system of multiple light receiving elements with an electrical signal processing system. By using orthogonal modulation and demodulation, the system achieves wavelength separation through mathematical operations rather than physical separation, reducing device complexity and size
2Measurement precision
If multiple LEDs are lit up exclusively to achieve simultaneous measurement at multiple wavelengths, then measurement precision is improved, but light emission time per wavelength decreases and S/N ratio degrades
Solution Approach 1:
The patent uses periodic modulation with orthogonal functions (sine, cosine, and higher-order harmonics) to enable simultaneous emission from multiple LEDs. This ensures that each wavelength component can be independently extracted through demodulation, maintaining sufficient light emission time for each wavelength while achieving simultaneous multi-wavelength measurement and improving S/N ratio
3Device complexity
If background light alone is used for object identification, then device complexity is reduced, but measurement stability deteriorates in low light environments
Solution Approach 1:
The patent replaces passive background light detection with an active illumination system using LEDs. By using modulated LED light, the system can distinguish between reflected LED light and ambient background light through frequency discrimination, enabling stable measurements in low light environments while maintaining relatively simple device architecture
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 apparatus achieves improved identification performance, adaptability to multiple wavelengths, and cost-effectiveness by separating wavelength components efficiently, while maintaining high signal-to-noise ratio and reducing motion blur, and operates effectively in varying light conditions.
Implementation Method 1
a plurality of light emitting elements that radiate in a predetermined direction light having different central wavelengths from one another
Implementation Method 2
at least one light receiving element that generates a signal in accordance with an intensity of received light in the predetermined direction
Implementation Method 3
the modulation pattern is defined by an orthogonal matrix in which an array of the plurality of light emitting elements serves as rows and their turn-on/off periods serve as columns
Implementation Method 4
a pulse modulation part that executes turn-on/off of each of the plurality of light emitting elements simultaneously in parallel in a predetermined modulation pattern in synchronization at a predetermined frequency
Data Source
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AI summary
[Problem to be Solved] To provide an object identification apparatus which is advantageous for improvement in identification performance, size reduction, and lowering of cost. [Solution] The object identification apparatus includes a plurality of light emitting elements that emit, in a predetermined direction, light having different central wavelengths from one another, at least one light receiving element that generates a signal in accordance with an intensity of received light in the predetermined direction, and a control unit that controls light emission periods of the plurality of light emitting elements and extracts a signal component at a wavelength corresponding to each of the plurality of light emitting elements from the signal, the object identification apparatus being configured to identify an object present in the predetermined direction based on reflectance found from the signal component. The control unit includes a pulse modulation part that executes turn-on/off of each of the plurality of light emitting elements simultaneously in parallel in a predetermined modulation pattern in synchronization at a predetermined frequency, and the modulation pattern is defined by an orthogonal matrix in which an array of the plurality of light emitting elements serves as rows and their turn-on/off periods serve as columns.