Adaptive Elastic Mode Cancellation in Flexible Aircraft Structures
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for aeroservoelastic coupling suppression in flexible structures with non-linear aerodynamics, such as those found in flying booms, are not robust enough to handle fast changes in structure morphology and exogenous boundary conditions, and require multiple sensors to effectively cancel elastic modes, which increases complexity and cost.
Innovation Solution
A real-time adaptive method using two active measurement sources and a combination of parametric band-pass and second-order band-pass digital filters to estimate and cancel elastic modes in discrete-time signals, allowing for robust online cancellation with minimal impact on rigid dynamics and reduced sensor requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If model-based filtering methods (notch filters, extended Kalman filters) are used to cancel elastic modes, then elastic mode cancellation is achieved, but robustness against plant uncertainties and adaptation to fast changes in structure morphology deteriorates
Solution Approach 1:
The patent implements adaptive filtering techniques where filter parameters (such as natural frequencies and mode shapes) are updated in real-time based on measured system responses. This dynamic adaptation allows the system to track fast changes in structure morphology and boundary conditions, resolving the contradiction between model-based robustness and adaptability to changing conditions.
Solution Approach 2:
The patent changes the parameters of the filtering system (filter coefficients, natural frequency estimates) based on measured data from the flexible structure. By continuously updating these parameters, the system maintains robust elastic mode cancellation while adapting to fast changes in structure morphology without requiring a complete remodelling of the system.
2Measurement precision
If spatial filtering technique with distributed sensor array is used to cancel elastic modes, then elastic mode cancellation performance is improved, but device complexity and number of sensors required increases
Solution Approach 1:
The patent makes each sensor in the distributed array multi-functional by using its measurements not only for local monitoring but also for system-wide elastic mode cancellation through adaptive filtering. This allows the system to achieve high cancellation performance with fewer sensors compared to traditional spatial filtering that requires dense sensor arrays.
Solution Approach 2:
The patent uses virtual sensor concepts where the adaptive filter creates virtual measurements of elastic mode contributions that are then subtracted from actual sensor readings. This copying approach allows elastic mode cancellation without requiring physical sensors at every location, reducing the total number of sensors needed while maintaining cancellation performance.
3Reliability
If notch filters are used to remove elastic modes from feedback signals, then elastic mode attenuation is achieved for medium to high frequency modes, but effectiveness deteriorates when elastic mode frequencies lie within control frequency bandwidth
Solution Approach 1:
The patent replaces static notch filters with dynamic adaptive filters that can adjust their frequency response in real-time. This allows the system to effectively cancel elastic modes across the entire control bandwidth, including low-frequency modes that static notch filters cannot handle, by dynamically tracking and filtering modes regardless of their frequency position.
Data Source
AI summary
A method of aeroservoelastic coupling suppression, and particularly, the field of real time adaptive cancellation of elastic modes in discrete-time signals which measure the dynamics of a flexible structure. The flexible structure comprises a structure with elastic variable characteristics, and more particularly, a structure with non-linear aerodynamics. A method is disclosed for adaptively cancelling, in real time, N elastic modes in discrete-time signals which measure the dynamics of the flexible structure. Also disclosed is a computer program implemented on a computing device, a system and an aircraft implementing the mentioned method.