Aircraft Vibration Prediction for Rotor Damage Detection Under Active Control
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Solution Overview
Problem
Active vibration reduction systems in aircraft mask changes in vibrations caused by rotor damage, making it difficult for existing Health and Usage Monitoring systems to detect malfunctions.
Innovation Solution
A method that estimates delta vibrations resulting from active vibration reduction adjustments and records second vibrations using sensors, generating a pseudo-vibration profile for comparison with a target profile to output a signal when a threshold is exceeded, allowing for the detection of rotor damage even with active vibration reduction systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If active vibration reduction systems are used to reduce rotor vibrations, then vibration levels in the aircraft cabin are reduced, but the ability to detect rotor damage through vibration changes is lost
Solution Approach 1:
The vibration signal is segmented into two components: the active control vibration (first vibration) estimated from control system adjustments, and the residual vibration (second vibration) measured by sensors. By separating these components and comparing the residual against reference profiles, the system maintains damage detection capability while active control reduces overall vibration levels.
Solution Approach 2:
A pseudo-vibration profile is introduced as an intermediary representation that combines estimated control vibrations with measured residual vibrations. This intermediary profile allows comparison with reference profiles to detect damage, effectively mediating between the conflicting requirements of vibration reduction and damage detection.
2Object-affected harmful factors
If active systems adjust control rods and trim tabs to counteract vibrations, then vibration amplitudes are reduced, but the vibration signature of rotor damage is masked
Solution Approach 1:
The method extracts the active control vibration component from the total vibration signal by estimating it from control system adjustments. This extracted component is then subtracted from the measured signal to isolate the residual vibration that contains damage signature information, effectively separating the useful information from the masking effect.
Solution Approach 2:
Instead of directly analyzing the total vibration signal which is masked by active control, the method inverts the approach by estimating what the control system is doing and subtracting that from the measured signal. This inversion reveals the underlying damage signature that would otherwise be hidden.
3Measurement precision
If Health and Usage Monitoring systems compare predicted and measured vibrations to detect damage, then damage can be detected in aircraft without active vibration control, but this method fails when active vibration reduction systems are present
Solution Approach 1:
The monitoring method is made dynamic by continuously estimating the active control vibration component based on real-time control system adjustments and flying state parameters. This dynamic estimation allows the system to adapt to changing control conditions while maintaining accurate damage detection capability across different operating scenarios.
Solution Approach 2:
The enhanced monitoring system achieves universality by working effectively both with and without active vibration control systems. When active control is present, it estimates and compensates for control vibrations; when absent, it reverts to standard comparison methods, making the system versatile across different aircraft configurations.
Data Source
AI summary
A method for predicting vibrations in an aircraft comprising an active vibration reduction system includes estimating a first vibration amplitude or frequency resulting from adjustments by the active vibration reduction system and the respective sensitivities of the aircraft depending on the flying state using a statistical mathematical process, recording a second vibration amplitude or frequency by a sensor, generating a pseudo-vibration profile by combining the first and second vibration amplitudes or frequencies, comparing the pseudo-vibration profile with a predefined target vibration profile, and outputting a signal when a specific threshold value has been exceeded.