Doppler Lidar Turbulence Detection Range Extension
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Solution Overview
Problem
Conventional Doppler lidar systems face limitations in measurement range and reliability due to the inverse relationship between signal intensity and distance, leading to increased noise and reduced accuracy at longer ranges, which is exacerbated by limited power and space on aircraft, making it difficult to effectively detect turbulence-induced hazards.
Innovation Solution
The system improves signal-to-noise ratio by monitoring airflow only in the flight direction before turbulence is detected, using a fixed laser beam and extending integration time in the turbulence detection mode, and switches to a two-dimensional display mode for pilot notification, with a gust alleviation mode that scans the laser beam vertically for enhanced data update rates and autopilot control inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the laser beam is scanned in two dimensions to monitor turbulence distribution, then the pilot can monitor the display at all times and take appropriate measures, but the pilot workload increases and the effective range is limited
Solution Approach 1:
The patent segments the monitoring function by introducing an automatic determination unit that separates the tasks of turbulence detection and pilot decision-making. The determination unit automatically identifies impending danger based on lidar data, while the pilot only needs to respond to notifications, thus reducing workload while maintaining detection reliability.
Solution Approach 2:
The system implements self-service through automatic determination and notification functions that operate autonomously. The determination unit automatically processes lidar data, identifies turbulence hazards, and notifies the pilot without requiring continuous manual monitoring, allowing the system to serve itself in the detection and warning process.
2Length of stationary object
If the transmission output is increased to improve far-range measurement performance, then the detection range can be extended, but the device size increases and energy consumption rises
Solution Approach 1:
The patent changes the integration time parameter dynamically based on detection mode. In far-range detection mode, the integration time is extended to accumulate more signal photons, improving detection capability without increasing transmission power. This allows extended detection range while maintaining low energy consumption by optimizing the temporal integration of received signals.
3Reliability
If the integration time is extended to improve signal-to-noise ratio, then the measurement reliability improves, but the data update rate decreases
Solution Approach 1:
The patent implements dynamic adjustment of integration time based on operational mode. In normal detection mode, longer integration times are used for high reliability. In gust alleviation mode, the system dynamically shortens integration time to prioritize rapid data updates for real-time control, allowing the system to adapt between reliability and productivity based on current needs.
4Productivity
If the laser beam is scanned vertically for gust alleviation mode, then the data update rate increases and autopilot control can be improved, but the measurement range decreases
Solution Approach 1:
The patent applies local quality by using vertical scanning concentrated near the aircraft for gust alleviation, rather than broad horizontal scanning. This focuses the measurement on the local region most critical for immediate turbulence mitigation, achieving high update rates for autopilot control where needed most, while accepting reduced range in non-critical areas.
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 expands the detection range to approximately 20 km without increasing device size or energy consumption, reduces pilot workload, and enables earlier turbulence detection and reduced fuselage shaking through improved airflow data for autopilot control.
Implementation Method 1
an irradiated light beam is scattered by fine aerosol floating in the atmosphere, the scattered beam is received
Implementation Method 2
the frequency variation amount (wavelength variation amount) according to the Doppler effect is measured, whereby the wind velocity is measured
Data Source
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Figure 3
Figure 4~5
AI summary
An object of the present invention is to provide a method for preventing turbulence-induced accidents that can expand a detection range to about 20 km without increasing the size of a device or increasing the energy consumption, can perform planar distribution monitoring of turbulence when the turbulence is detected in the flight direction and also can output a signal for autopilot steering input that decreases the fuselage shaking when the turbulence is difficult to avoid, as well as to provide a device having those functions. In the method for preventing turbulence-induced accidents according to the present invention, an optical remote airflow measurement device of a Doppler lidar system using a laser beam is used to routinely enable distant turbulence to be detected by fixing a laser emission course in a flight direction and taking a long integration time of a reception signal, and to enable planar distribution of the turbulence to be displayed when turbulence is detected, by scanning the laser emission course in a horizontal direction and switching an image display to a two-dimensional display.