Aircraft Control Surface Detection Using RARX Signal Analysis
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Solution Overview
Problem
Current methods for detecting blockages and boardings of aircraft control surfaces in servo-controlled systems are inadequate in terms of speed and reliability, leading to potential aircraft performance and structural load issues.
Innovation Solution
A method using a recursive autoregressive model with exogenous variables (RARX) to estimate parameters of the control surface servo loop dynamics, followed by a decision test to detect blockages and boardings, which allows for early and accurate detection without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional detection methods are used for control surface blockage and boarding, then the system structure remains simple, but the detection speed and reliability are insufficient
Solution Approach 1:
The patent replaces traditional mechanical or simple sensor-based detection systems with a signal processing-based detection method. By analyzing the servo command signals and control surface position feedback through spectral analysis and coherence functions, the system detects blockage and boarding conditions without additional mechanical sensors or complex hardware modifications.
Solution Approach 2:
The patent introduces signal processing algorithms as an intermediary between the existing servo control system and the detection function. The coherence function and spectral analysis act as mediators that extract diagnostic information from normal operational signals, enabling reliable detection without direct physical intervention in the control surface mechanism.
2Speed
If detection is delayed, then the system operation remains stable, but aircraft performance deteriorates and structural loads increase
Solution Approach 1:
The patent performs preliminary detection by continuously monitoring the coherence between servo commands and control surface responses during normal operation. By establishing baseline coherence levels and detecting deviations in real-time, the system identifies blockage or boarding conditions early, before they significantly impact aircraft performance or create dangerous structural loads.
3Measurement precision
If additional sensors are added to improve detection accuracy, then measurement precision improves, but device complexity and mass increase
Solution Approach 1:
The patent enables the existing servo control system to perform self-diagnosis by analyzing its own operational signals. The coherence function calculates the relationship between commanded and actual control surface positions using only signals already present in the flight control system, allowing the system to detect its own anomalies without external monitoring equipment.
Data Source
Figure 1
Figure 2~3
AI summary
- The detection device (1) includes first means (22) for estimating the value of at least one parameter of an equation modeling the dynamics of the control loop of the rudder (3), in accordance with a recursive autoregressive method with exogenous variable of type RARX in the sense of recursive least squares, and second means (25) for detecting a blockage and/or a boarding of said rudder (3), as a function at least of the value thus estimated of said parameter by the application of a decision test in the parametric space.