Rotary Encoder for Landing Gear Stroke Measurement
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Solution Overview
Problem
Conventional aircraft landing gear systems using linear variable differential transformers (LVDTs) face inaccuracies in piston stroke measurement due to electromagnetic interference and require excessive mechanical components that wear over time, leading to errors in stroke calculation.
Innovation Solution
A configurable rotary encoder is introduced, rotatably coupled to the upper torque link pin, which eliminates the need for additional mechanical components and provides more accurate stroke measurements by calibrating the output to account for mechanical tolerances and electromagnetic field interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If LVDT is used to measure piston stroke, then measurement capability is provided, but measurement precision deteriorates due to electromagnetic interference and mechanical wear
Solution Approach 1:
The patent replaces the LVDT electromechanical measurement system with a rotary encoder that uses optical or magnetic fields to measure angular position. This substitution eliminates the mechanical contact components (armature, coils) that are susceptible to electromagnetic interference and wear, thereby improving measurement precision while reducing vulnerability to harmful factors.
Solution Approach 2:
The patent introduces a rotary encoder as an intermediary measurement device between the piston mechanism and the control system. The encoder converts linear piston motion into rotational angular position measurements through a linkage mechanism, providing accurate stroke measurement without direct electromagnetic interference with the piston system and reducing mechanical wear through non-contact sensing.
2Reliability
If LVDT with mechanical components is used, then stroke measurement is enabled, but reliability deteriorates due to component wear over time
Solution Approach 1:
The patent replaces mechanical contact components in the measurement system with a rotary encoder that utilizes optical or magnetic fields for sensing. This eliminates wear-prone mechanical elements such as the LVDT armature and sliding contacts, significantly extending the service life and reliability of the measurement system while maintaining continuous operation capability.
3Measurement precision
If rotary encoder is used without calibration, then device complexity is reduced, but measurement precision deteriorates due to mechanical tolerances
Solution Approach 1:
The patent implements a calibration procedure that is performed in advance during system installation or maintenance. The calibration process establishes the relationship between rotary encoder angular position and actual piston stroke by measuring known reference positions. This preliminary action compensates for mechanical tolerances and mounting variations, enabling high measurement precision without requiring complex real-time correction systems.
Solution Approach 2:
The patent incorporates a calibration mechanism that allows the system to determine accurate stroke measurements by referencing known positional data. The calibration process creates a mapping between encoder readings and actual piston positions, which is stored and used for ongoing measurements. This feedback-based approach maintains high precision while keeping the operational system relatively simple.
Data Source
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AI summary
A landing gear system includes a landing gear collar and a strut assembly supported by the landing gear collar. The strut assembly includes a piston that is adjustable between a fully extended position and a fully compress position. The landing gear system further includes a rotary encoder and a controller. The rotary encoder rotates in response adjusting the piston and to outputs a data value in response to its rotation. The controller is in signal communication with the rotary encoder and determines a stroke of the piston based on the data value output from the rotary encoder.