Aerodynamic Vehicle Control Effectors Avoiding Structural Mode Resonance
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Solution Overview
Problem
Control structure interaction (CSI) issues in aerodynamic vehicles lead to unstable structural dynamics and excessive fatigue, often requiring rigid designs or frequency filtering, which increase costs and reduce performance.
Innovation Solution
The method controls actuation of control effectors based on the mode shape direction of structural modes excited by actuation, emphasizing orthogonal actuation to avoid CSI without stiffening the vehicle or degrading performance, using modal influence functions and feedback signals to adjust actuator commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the aerodynamic vehicle is designed to be rigid and stiff to avoid CSI, then control structure interaction is reduced, but vehicle weight increases
Solution Approach 1:
The patent changes the frequency parameter of control inputs to avoid resonating with structural modes. By modifying the temporal characteristics of control signals (using frequency-dependent filters), the system achieves CSI mitigation without altering the physical structure or increasing weight.
Solution Approach 2:
The patent introduces frequency-dependent filters as an intermediary element between the control system and structural modes. These filters mediate the interaction by selectively attenuating frequency components that would excite structural resonances, thereby reducing CSI without requiring structural stiffening.
2Reliability
If frequency dependent filters are used to reduce CSI, then control structure interaction is mitigated, but flight control system performance is reduced
Solution Approach 1:
The patent applies partial filtering by selectively attenuating only the specific frequency components that excite structural modes, rather than broadly filtering all frequencies. This partial action approach maintains control effectiveness for non-resonant frequencies while mitigating CSI at problematic frequencies.
Solution Approach 2:
The patent dynamically adjusts filtering parameters based on operating conditions and identified structural modes. By changing filter characteristics (cutoff frequencies, attenuation levels) according to current flight parameters, the system optimizes the balance between CSI mitigation and control performance.
Data Source
AI summary
Methods and computer program products are provided for controlling a plurality of control effectors of an aerodynamic vehicle based upon the mode shape direction of one or more structural modes excited by actuation of the control effectors. For example, control of the actuation of the control effectors may be provided to emphasize actuation of those control effectors that affect a structural mode having a mode shape direction that is substantially orthogonal to the mode shape of the structural mode. By affecting a structural mode in such a manner that the mode shape direction is substantially orthogonal to the mode shape of the structural mode, control structure interaction (CSI) is avoided without having to design a stiffer aerodynamic vehicle and without having to filter the sensor input and/or the actuator commands, unless it is otherwise desirable to do so.