Rotorcraft Airspeed Estimation via Vibration Amplitude
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Solution Overview
Problem
In aerospace applications, particularly for rotorcraft, rotor downwash often leads to unreliable airspeed data from conventional sensors, especially at low speeds, due to interference and inaccuracies.
Innovation Solution
A computing system that determines airspeed based on the amplitude of vibration, utilizing a band-pass filter, absolute value algorithm, and rolling window maximum algorithm, combined with inertial measurement units and health and usage monitoring systems, to calculate airspeed independently of directional properties, thereby providing reliable airspeed data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional airspeed sensors are used in rotorcraft, then airspeed measurement is possible, but the data becomes unreliable at low speeds due to rotor downwash interference
Solution Approach 1:
The patent introduces rotor vibrations as an intermediary phenomenon to indirectly measure airspeed. Instead of directly measuring airspeed through conventional sensors that are affected by rotor downwash, the system uses the vibrations generated by the rotor blades interacting with the air as a mediator to derive airspeed information. The vibration amplitude serves as a proxy measurement that is not contaminated by the rotor downwash effect.
Solution Approach 2:
The patent replaces the conventional mechanical airspeed sensing system (which uses physical sensors in the airflow path) with a vibration-based measurement system. By substituting the direct mechanical measurement approach with a vibration analysis approach, the system eliminates the interference problem caused by rotor downwash while maintaining airspeed measurement capability.
2Reliability
If rotor vibrations are used to determine airspeed, then reliable airspeed data is obtained at low speeds, but the measurement system becomes more complex requiring signal processing algorithms
Solution Approach 1:
The patent segments the vibration signal into distinct frequency components corresponding to different rotor blade interactions with the air. By separating the signal processing into discrete frequency bands and analyzing specific harmonic components, the system manages the complexity through structured decomposition rather than attempting to analyze the entire vibration spectrum as a single complex signal.
Solution Approach 2:
The patent deliberately utilizes and amplifies the mechanical vibration phenomenon generated by rotor blade interactions with the air. By focusing on extracting meaningful information from the natural vibrations rather than trying to eliminate or avoid them, the system transforms a potentially complex disturbance into a useful measurement signal through targeted frequency analysis.
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 method provides accurate airspeed calculations, reducing reliance on conventional sensors and enhancing flight control parameter scheduling, with an estimate accuracy sufficient for flight control within +/- 10 knots, even at low speeds.
Implementation Method 1
rotor downwash may cause most airspeed sensors to provide unreliable data
Implementation Method 2
Airspeed determination based on an amplitude of a vibration
Data Source
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AI summary
Embodiments are directed to determining, by a computing device comprising a processor, at least one parameter associated with a rotorcraft, obtaining, by the computing device, a profile of a vibration associated with the operation of the rotorcraft based on the at least one parameter, determining, by the computing device, an amplitude of the vibration using the profile, and determining, by the computing device, an airspeed of the rotorcraft based on amplitude.