Slat Flap Lever Position Detection Using RFID Tags
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Solution Overview
Problem
Current slat flap lever controls in aircrafts, utilizing rotary variable differential transformers (RVDTs), face reliability issues due to air gap changes and channel-to-channel variations, leading to inaccurate position detection over time.
Innovation Solution
A position detection system utilizing a multi-channel RFID reader and tags, where each channel communicates with a group of RFID tags to determine the angular position of the lever with high accuracy, reducing complexity and weight by using a digital bus and contactless sensors, and providing redundancy for precise position measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If analog levers with RVDTs are used for position detection, then position measurement capability is provided, but reliability deteriorates over time due to air gap changes and channel-to-channel variation
Solution Approach 1:
The patent replaces the mechanical RVDT system with a magnetic field-based sensing system using Hall effect sensors. This substitution eliminates the mechanical air gap issues and contact wear problems inherent in RVDTs, providing contactless position detection that maintains both reliability and measurement precision over time.
Solution Approach 2:
The patent changes the detection parameter from electrical signal transformation in RVDTs to magnetic field sensing via Hall effect. By measuring the magnetic field strength at different positions along the lever travel, the system achieves accurate position detection without the reliability issues of mechanical transformation systems.
2Measurement precision
If multi-channel RFID reader with multiple RFID tags is used, then measurement precision and redundancy are improved, but device complexity increases
Solution Approach 1:
The patent divides the position detection range into multiple discrete angular positions, with each position detected by a dedicated RFID tag. This segmentation allows precise detection at specific positions while using a single RFID reader, reducing overall system complexity compared to continuous sensing systems.
Solution Approach 2:
The patent uses multiple RFID tags at different angular positions as simple copies of the detection target. Each tag provides a binary presence/absence signal that indicates lever position, eliminating the need for complex continuous measurement systems while maintaining high precision at discrete positions.
3Weight of moving object
If wire-wound RVDTs are eliminated and digital bus is used, then wiring harness weight is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent replaces the physical wire-wound RVDT assembly with a digital communication system using a bus. This substitution dramatically reduces wiring harness weight and complexity, as digital signals can be transmitted through existing control system buses rather than requiring dedicated heavy wiring for analog signals.
Solution Approach 2:
The patent makes the digital bus serve multiple functions: it transmits position data from multiple Hall effect sensors, provides power to the sensors, and enables communication with the flight control system. This multi-functionality reduces the need for separate wiring harnesses, thereby reducing weight while managing manufacturing precision through standardized digital interfaces.
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 enhances the reliability and accuracy of slat flap lever position detection, reducing errors to within ±1 mm and improving system reliability by eliminating wire-wound RVDTs and reducing wiring harness weight, while maintaining precise sensing and position correction.
Implementation Method 1
a multi-channel radio frequency identification (RFID) reader configured on a stationary portion of the lever assembly and adapted for signal output at multiple frequencies
Implementation Method 2
at least one Hall effect sensor configured on the movable lever portion and configured to detect position of the lever
Data Source
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AI summary
A system for positional monitoring of a slat flap lever control assembly (10) including multiple radio frequency identification device (RFID) tags (24) operatively coupled to a movable portion (40) of the control assembly, the movable portion operatively coupled to a lever (14). Also included is a RFID reader (22) operatively coupled to a stationary portion (42) of the control assembly and in operative communication with the RFID tags. Further included is a processor operatively connected to the RFID reader. The processor is configured to transmit a carrier signal via the RFID reader to the RFID tags. The processor is also configured to receive, via the RFID reader, reflected signals from the RFID tags, each of the reflected signals comprising a different carrier frequency. The processor is further configured to determine, based on the reflected signal from the RFID tags, an angular position of the movable portion of the lever assembly relative to the stationary portion.