Optical Telemetry Using Incoherent Light for Distance Measurement
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Solution Overview
Problem
Existing optical telemetry systems for measuring distance between moving objects, such as vehicles, require expensive coherent and directive light sources, are sensitive to interference, and cannot utilize existing vehicle lights, which are polychromatic and incoherent, limiting their applicability and accuracy.
Innovation Solution
An optical telemetry system utilizing conventional light sources like white or colored LEDs or electric filament lamps, which are incoherent and polychromatic, employing a phase-locked loop and heterodyne processing to measure phase shift and distance, allowing the use of existing vehicle lights and improving resistance to interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coherent and directive light sources (laser) are used for optical telemetry, then measurement precision and reliability are improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces expensive, complex coherent light sources (lasers) with inexpensive, simple incoherent light sources such as LEDs or conventional lamps. This substitution maintains adequate measurement precision for the intended application range (tens of centimeters to tens of meters) while dramatically reducing system complexity and cost, making the system suitable for widespread deployment in vehicles and industrial applications
2Measurement precision
If coherent light sources are used for optical telemetry, then measurement precision is improved, but sensitivity to interference increases
Solution Approach 1:
The patent employs incoherent light sources that are inherently more resistant to interference from other optical sources and environmental conditions. This approach maintains measurement precision while reducing sensitivity to harmful interference factors, enabling reliable operation in complex electromagnetic and optical environments such as heavy traffic scenarios
Solution Approach 2:
The patent modifies the fundamental parameter of light coherence, transitioning from coherent to incoherent light sources. This parameter change fundamentally alters the system's interference characteristics, making it more robust against external interference while maintaining adequate measurement precision for the intended application range
3Device complexity
If conventional incoherent light sources are used, then device complexity and cost are reduced, but measurement precision deteriorates
Solution Approach 1:
The patent changes the coherence parameter of the light source from coherent to incoherent, which simplifies the system while maintaining adequate measurement precision for the specific application range of tens of centimeters to tens of meters. The precision requirements for this range do not demand the full performance of coherent sources
Solution Approach 2:
The patent uses simple, inexpensive incoherent light sources like LEDs or conventional lamps that are already widely available in vehicles and industrial equipment. This substitution reduces system complexity and cost while providing sufficient measurement precision for the intended application scenarios, making the system economically viable and easier to deploy
4Reliability
If coherent light sources are used, then reliability is improved, but adaptability deteriorates because existing vehicle lights cannot be utilized
Solution Approach 1:
The patent makes the optical telemetry system compatible with existing vehicle lighting infrastructure by using incoherent light sources that can be the same LEDs or lamps already installed for illumination and signaling. This universality allows the system to leverage existing vehicle lights, reducing component count and integration complexity while maintaining adequate reliability for the application
Solution Approach 2:
The patent uses standard, widely-available incoherent light sources that are already present in vehicles for other functions. This approach reduces the need for specialized components, simplifies integration with existing vehicle systems, and maintains sufficient reliability for distance measurement applications
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 accurate distance measurement between moving vehicles using existing vehicle lights, reducing costs and interference sensitivity, and allowing for the use of incoherent light signals, thereby enhancing the system's applicability and reliability.
Implementation Method 1
a light source SLs emitting a beam 3 in the direction of a followed vehicle (4)
Implementation Method 2
a photosensitive sensor CPs oriented towards the rear of the vehicle (1)
Implementation Method 3
employing a phase-locked loop and heterodyne processing to measure phase shift and distance
Implementation Method 4
employing a phase-locked loop and heterodyne processing to measure phase shift and distance
Data Source
AI summary
The present invention relates to an optical telemetry system for measuring the distance between two vehicles comprising a first optoelectronic assembly formed by at least one light source SLs and at least one photosensitive sensor CP+, which source and sensor are oriented towards in front of the vehicle, and a second optoelectronic assembly formed by at least one light source SLc (6) and at least one photosensitive sensor CPc (5) that is oriented towards behind the vehicle, characterized in that said light sources SLs and SLc are conventional light sources, the light source SLs being modulated by a signal of frequency Fs, said light source SLc (6) of the target (4) being modulated by a clock of frequency controlled by a phase-locked loop driven by the electrical signal delivered by said photosensitive sensor CPc, said first optoelectronic assembly furthermore comprising a circuit for measuring the phase shift between the electrical signal delivered by said photosensitive sensor CPs (5) and the signal modulating the paired light source SLs (6), said system furthermore comprising a computer for determining the distance depending on the frequency Fs and the measured phase shift. The invention also relates to an optoelectronic assembly for an optical telemetry system, to a vehicle equipped with such a system and to a telemetry method.