Multi-Wavelength Time-of-Flight Distance Measurement
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Solution Overview
Problem
Time-of-flight (TOF) systems in multi-user environments face interference issues due to the presence of multiple systems, leading to incorrect distance measurements, which can be dangerous in applications like automated guided vehicles, and existing solutions like time-multiplexing and pseudo-noise modulation have limitations such as increased costs, latency, and vulnerability to malicious participants.
Innovation Solution
A method using at least two wavelengths and varying pulse repetition rates for distance measurement, where each TOF system broadcasts its pulse repetition rate and wavelength independently, allowing for immune distance calculation by determining the most frequent time of arrival in a statistical distribution, thereby reducing interference and eliminating the need for central coordination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time-multiplexing is used to resolve multi-user interference, then interference between TOF systems is reduced, but system complexity and coordination requirements increase
Solution Approach 1:
The patent changes the wavelength parameter of the light source to resolve multi-user interference. Each TOF system operates at a different wavelength, allowing simultaneous operation without interference. This eliminates the need for time-multiplexing coordination while maintaining measurement accuracy.
2Reliability
If pseudo-noise modulation is used to mitigate interference, then measurement robustness improves, but latency increases
Solution Approach 1:
The patent changes the wavelength parameter instead of using pseudo-noise modulation. This allows direct measurement without the need for complex correlation processing, thereby reducing measurement latency while maintaining interference resistance through wavelength differentiation.
3Productivity
If multiple TOF systems operate simultaneously in the same environment, then productivity increases, but measurement accuracy deteriorates due to interference
Solution Approach 1:
The patent assigns different wavelengths to each TOF system, allowing multiple systems to operate simultaneously without mutual interference. The wavelength filter in each system only passes the specific wavelength of its own light source, blocking signals from other systems and maintaining measurement precision.
4Measurement precision
If wavelength filtering is applied to each detector, then signal-to-noise ratio improves, but device complexity increases
Solution Approach 1:
The patent uses fixed wavelength filters matched to each light source wavelength. This simplifies the system design compared to tunable filters, as each detector is permanently configured for its specific wavelength, reducing control complexity while maintaining high signal-to-noise ratio.
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 effectively mitigates multi-user interference, ensuring accurate and real-time distance measurements without relying on cooperation or benevolence of other systems, and is resistant to malicious participants, improving the signal-to-noise ratio and reducing the risk of false measurements.
Implementation Method 1
irradiating the environment by means of a series of light pulses, wherein this series of light pulses are emitted by a battery of at least two single light source devices emitting on at least two different wavelengths
Implementation Method 2
collecting pulses that are reflected or scattered from the environment
Implementation Method 3
at least one detector equipped with a wavelength filter whose pass band corresponds to the selected emitted wavelength
Implementation Method 4
assigning a timestamp at the detection of a pulse by means of at least one chronometer connected to the detector, said timestamps corresponding to the time of arrival (TOA)
Data Source
AI summary
A method for measuring a distance to a target in a multi-user environment, comprising: irradiating the environment by a series of light pulses, wherein this series of light pulses is emitted by a battery of at least two or a single light source device emitting on at least two different wavelengths, the light pulses being emitted at a determined repetition rate and with a determined randomly selected wavelength; collecting pulses reflected or scattered from the environment to at least one detector equipped with a wavelength filter whose pass band corresponds to the selected emitted wavelength; assigning a timestamp at the detection of a pulse by at least one chronometer connected to the detector, said timestamps corresponding to the time of arrival (TOA); determining the statistical distribution of said time of arrivals; determining the distance to the target from said statistical distribution.