Aircraft Landing Gear Tachometer Low-Speed Accuracy
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Solution Overview
Problem
Existing tachometer systems for aircraft landing gear are inaccurate at low rotation speeds due to low signal-to-noise ratios, which prevents them from accurately determining wheel speed, especially when the landing gear incorporates an electrical drive system or when the aircraft is stationary.
Innovation Solution
A tachometer system that uses determined parameters from the variable voltage signal's voltage levels to process and filter the signal, allowing existing tachometers designed for high speeds to accurately measure low speeds without additional sensors, by employing a processing system that includes a frequency filter and dynamic relay to remove noise and adjust thresholds based on voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing tachometers are used for high-speed measurements, then high-speed measurement accuracy is maintained, but low-speed measurement accuracy deteriorates due to low signal-to-noise ratios
Solution Approach 1:
The patent applies dynamics by making the filtering and processing parameters adaptive rather than fixed. The processing system dynamically adjusts filter characteristics and processing gains based on the detected signal-to-noise ratio, which varies with rotation speed. This allows the tachometer to optimize its performance for each operating condition, maintaining accuracy across both high and low speed ranges without requiring separate dedicated sensors for each regime.
Solution Approach 2:
The patent implements parameter changes by modifying the processing parameters (filtering characteristics, threshold levels, integration times) based on the operating conditions and signal quality. The system detects the signal-to-noise ratio and adjusts processing parameters accordingly, transforming a static measurement system into one that adapts its parameters to maintain optimal performance across varying rotation speeds and signal conditions.
2Reliability
If signal filtering is applied to remove noise, then measurement robustness is improved, but signal processing complexity increases
Solution Approach 1:
The patent employs feedback by continuously monitoring the signal-to-noise ratio and using this information to adjust the filtering and processing parameters in real-time. The processing system analyzes the incoming signal characteristics and feeds this information back to modify its own processing behavior, creating a closed-loop system that automatically optimizes noise rejection while maintaining signal integrity without requiring complex manual configuration.
Solution Approach 2:
The processing system performs self-service by automatically detecting signal conditions and adjusting its own processing parameters without external intervention. The system monitors its own input signal quality and autonomously modifies filtering strength, threshold levels, and integration parameters to maintain optimal performance, reducing the need for complex external control systems or manual calibration procedures.
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 accurate rotation speed measurements at both high and low speeds, improving the accuracy of existing tachometer systems and enabling their use in low-speed applications without requiring special tachometers, while filtering out unwanted noise to ensure robustness.
Implementation Method 1
the interaction of the rotor and stator of the tachometer 5 during rotation of the wheel 2 cause the tachometer 5 to generate a variable voltage electrical signal
Data Source
AI summary
A tachometer system for an aircraft landing gear. The tachometer system includes a tachometer arranged to generate a variable voltage signal in response to the rotation of a wheel of the aircraft landing gear, and a processing system arranged to output a speed signal indicative of the rotation speed of the wheel of the aircraft landing gear. The speed signal is determined from the variable voltage signal from the tachometer using a set of determined parameters. The determined parameters of the processing system are determined from the voltage levels of the variable voltage signal.