Hybrid LIDAR Air Data Sensing for Accurate Pressure Altitude
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Solution Overview
Problem
Current LIDAR systems for aircraft air data measurements suffer from inaccuracies in pressure and calibrated airspeed, failing to meet governmental certification requirements and lacking the precision of traditional pitot-static systems, which require extensive calibration and are sensitive to aerodynamic disturbances.
Innovation Solution
An aircraft system combining a LIDAR system with independent sensors to detect total pressure and total temperature, using a control unit to calculate air data parameters such as pressure altitude, calibrated airspeed, and Mach number, thereby augmenting LIDAR measurements for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If LIDAR systems are used to measure air data, then the need for traditional pitot-static systems and their extensive calibration is reduced, but the measurement precision of pressure and calibrated airspeed deteriorates
Solution Approach 1:
The patent combines LIDAR velocity measurements with total pressure sensor measurements in a hybrid system. The LIDAR provides accurate velocity data while the total pressure sensor provides pressure data, and these are merged through atmospheric density calculations to derive both velocity and pressure altitude with high accuracy, eliminating the need for extensive calibration of either system alone.
Solution Approach 2:
The patent uses atmospheric density as an intermediary parameter that connects velocity measurements from LIDAR with pressure measurements from total pressure sensors. By calculating density from the combined measurements and using it as a mediator, the system can accurately determine both calibrated airspeed and pressure altitude without requiring extensive calibration of individual sensors.
2Measurement precision
If traditional pitot-static systems are used, then pressure altitude measurement accuracy meets certification requirements, but the system requires extensive aerodynamic modeling, wind tunnel testing, and flight testing
Solution Approach 1:
The patent replaces the mechanical pitot-static system with an optical LIDAR system combined with a simplified total pressure sensor. The LIDAR uses laser scattering to measure velocity directly without mechanical moving parts, and the total pressure sensor requires minimal calibration compared to traditional pitot-static systems, thereby reducing aerodynamic modeling and wind tunnel testing requirements.
Solution Approach 2:
The patent changes the measurement parameters from direct static pressure measurement (which requires complex calibration) to a hybrid approach using LIDAR velocity measurements combined with total pressure measurements. This parameter change allows the system to achieve accurate pressure altitude measurements through calculation rather than direct measurement, reducing calibration complexity.
3Adaptability or versatility
If LIDAR systems use Rayleigh scattering to measure air data, then temperature and pressure can be determined, but the accuracy of pressure and calibrated airspeed measurements deteriorates due to large uncertainties
Solution Approach 1:
The patent segments the measurement functions by using LIDAR specifically for velocity measurements through Doppler shift detection, while using total pressure sensors for pressure measurements. This segmentation allows each sensor to optimize its specific measurement function, with LIDAR providing accurate velocity data without the pressure measurement uncertainties that plague Rayleigh scattering systems.
4Measurement precision
If LIDAR systems use Mie scattering to measure air data, then true airspeed can be measured, but the capability to sense temperature and pressure deteriorates
Solution Approach 1:
The patent creates a multi-functional system where LIDAR measurements of true airspeed are combined with total pressure sensor measurements to simultaneously determine velocity, pressure altitude, and atmospheric density. This universal approach allows the system to perform multiple measurement functions that neither LIDAR nor total pressure sensors could achieve alone, restoring the temperature and pressure sensing capability while maintaining accurate true airspeed measurement.
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 system provides highly accurate air data measurements with minimal a priori flight testing, reducing the need for extensive calibration and enabling reliable operation across various aircraft types and flight conditions.
Implementation Method 1
The LIDAR systems fundamentally rely on the scattering of light
Implementation Method 2
Some LIDAR systems are based on Rayleigh scattering in which the laser light is elastically scattered from molecules in the atmosphere
Implementation Method 3
Other LIDAR systems are based on Mie scattering in which laser light is scattered from particles in the atmosphere
Implementation Method 4
The LIDAR systems measure the Doppler shift between the laser beams and the air molecules in the air mass to measure true airspeed
Data Source
AI summary
An aircraft system having a LIDAR system, one or more sensors, and a control unit. The control unit includes processing circuitry configured to calculate during flight a pressure altitude, calibrated airspeed, Mach number, equivalent airspeed, static temperature, static pressure, and dynamic pressure of an aircraft based on a combination of air data measurements from the LIDAR system and the one or more sensors.