Air Refuelling Boom Damping via Resonance-Filtered Angular Velocity
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Solution Overview
Problem
In-flight refuelling systems face challenges with structural coupling due to low damping ratios and resonance frequencies, which affect the stability and handling qualities of the boom during fuel transfer, making it difficult to achieve precise and predictable movement without oscillations.
Innovation Solution
A method and system that utilize at least two position and/or movement sensors placed on opposite sides of the dominant flexible mode's valley to calculate an angular velocity unaffected by resonance, using weighting factors proportional to the moduli of angular deformations to eliminate elastic movement components and ensure a 180° phase lag, thereby increasing damping and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the boom is designed with low weight and long length, then the structural characteristics exhibit low frequency flexible modes with very low damping ratio, but this causes structural coupling phenomenon and resonance when excited at natural frequency
Solution Approach 1:
The patent replaces mechanical filtering approaches with signal processing techniques. Sensors measure angular positions, and the control system computationally extracts rigid body motion signals by eliminating flexible mode components through mathematical operations, substituting mechanical damping with electronic signal processing.
Solution Approach 2:
The patent introduces sensors as intermediary elements that measure angular positions at multiple locations. These sensors act as mediators between the physical boom motion and the control system, enabling the extraction of pure rigid body motion signals through computational processing of sensor data.
2Stability of the object's composition
If aerodynamic fins are used to increase damping of angular movements, then the damping effect is achieved by fin movement related to angular velocity, but this excites the flexible modes of the boom structure
Solution Approach 1:
The patent implements feedback control where sensors continuously measure angular positions, the control system processes these signals to determine rigid body motion components, and aerodynamic fins are actuated based on this processed feedback to provide damping forces that counteract oscillations without exciting flexible modes.
Solution Approach 2:
The patent changes the control parameter from direct angular position control to control based on processed angular velocity signals that have had flexible mode components removed. This parameter transformation allows the aerodynamic fins to respond only to rigid body motion, avoiding excitation of flexible structures.
3Measurement precision
If sensors are used to measure movement and position for control algorithms, then the control system can generate commands for fin movement, but the sensors detect both rigid movement and flexible vibration which couples structure and control
Solution Approach 1:
The patent segments the motion signal into two distinct components: rigid body motion and flexible vibration. By placing sensors at strategic locations and using computational methods, the control system separates these coupled motions into independent signals, allowing control based solely on rigid body dynamics without flexible mode contamination.
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
This approach enhances damping and stability margins in flexible modes, reducing structural coupling and improving handling qualities by isolating the boom's movement from resonance effects, ensuring reliable and precise fuel transfer operations.
Implementation Method 1
aerodynamic control surfaces or fins which, by means of independent variations of the incidence of each of them relative to the incident air flow, enables the operator of the system to position the boom in the conditions of desired attitude
Implementation Method 2
the control algorithms must perform a basic function of increasing the damping of the basic equipment, from a very low value, close to zero, up to a value compatible with a rapid and predictable response without oscillations
Data Source
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AI summary
A method for controlling a boom (11) for in-flight refuelling for increasing the damping of its displacement by means of a movement of control surfaces (16) related to its angular velocity, that comprises the following steps: a) At least two sensors (32, 33) are arranged in two sections of the boom (11) positioned on opposite sides of the valley (41) of the dominant flexible mode (40) for any length of its telescopic extension (12) and the moduli (D1, D2) of the angular deformations of the dominant flexible mode (40) are determined in them; b) The angular velocities (Q1, Q2) are obtained from the data supplied by said sensors (32, 33); c) The angular velocity Q unaffected by the resonance of the dominant flexible mode (40) is obtained as a function of said angular velocities (Q1, Q2) and said moduli (D1, D2), which eliminates the component of the elastic movement of the dominant flexible mode (40). The invention also relates to a control system and a computer program for executing said method.