FMCW LiDAR Distance Measurement Precision Correction
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Solution Overview
Problem
FMCW LiDAR systems face precision issues in distance and velocity measurement due to nonlinear changes in frequency modulation caused by changes in the light source's operating state, environment, and over time, leading to fluctuations in beat signal frequency.
Innovation Solution
A measurement apparatus with a light source, calibrating optical system, interference optical system, photosensitive device, and processing circuit that generates correcting data based on second interfering light to correct first detection signals, ensuring precise distance and velocity measurements despite changes in the light source's characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency modulation is applied to the light source, then distance and velocity measurement is enabled, but nonlinear changes in frequency modulation occur due to light source characteristic changes, leading to measurement precision deterioration
Solution Approach 1:
The patent implements a feedback mechanism where the measured distance information is used to correct the frequency modulation timing. A timing correction value is calculated based on the measured distance and applied to adjust the frequency modulation timing, compensating for nonlinearities. This closed-loop feedback ensures that frequency modulation remains linear despite light source characteristic changes, maintaining measurement precision.
Solution Approach 2:
The patent dynamically adjusts the frequency modulation timing parameters based on measured distance information. By changing the timing parameter according to the measured distance, the system compensates for nonlinear frequency modulation effects. This parameter adjustment allows the system to maintain accurate distance and velocity measurements even when light source characteristics drift over time or with environmental changes.
2Productivity
If the light source operates over extended periods and varying environments, then continuous measurement capability is maintained, but light source characteristics change, causing beat signal frequency fluctuations and measurement errors
Solution Approach 1:
The system continuously performs feedback correction by measuring distance, calculating timing correction values, and adjusting frequency modulation timing in real-time. This continuous feedback loop compensates for light source characteristic changes that occur during extended operation and environmental variations, maintaining measurement precision throughout the operational period.
Solution Approach 2:
The patent employs dynamic adjustment of frequency modulation timing based on real-time measurement data. The timing correction is continuously updated according to the measured distance, allowing the system to adapt to changing light source characteristics during operation. This dynamic approach enables continuous measurement while maintaining accuracy despite environmental and temporal variations.
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 maintains high precision in distance and velocity measurements by dynamically updating correcting data, compensating for nonlinear frequency modulation and environmental changes, thereby reducing measurement errors.
Implementation Method 1
a light source that emits frequency-modulated light
Implementation Method 2
generates first interfering light that is interfering light resulting from interference between reflected light produced when the frequency-modulated light reflects off a physical object and reference light
Implementation Method 3
a photosensitive device that outputs a first detection signal corresponding to an intensity of the first interfering light and a second detection signal corresponding to an intensity of the second interfering light
Implementation Method 4
the velocity of the physical object can be calculated too through the utilization of a Doppler shift for the reflected light from the physical object
Data Source
AI summary
A measurement apparatus includes a light source, a calibrating optical system, an interference optical system, a photosensitive device, a storage device, and a processing circuit. The interference optical system separates the light into reference light and output light and generates first interfering light and second interfering light. The photosensitive device outputs a first detection signal corresponding to an intensity of the first interfering light and a second detection signal corresponding to an intensity of the second interfering light. The processing circuit sends out, to the light source, a control signal that sweeps a frequency of the light that is emitted from the light source, updates, on the basis of the second detection signal, the correcting data stored in the storage device, and generates measurement data on the basis of the correcting data thus updated and the first detection signal.