Aircraft Control Bandwidth Adaptation for Structural Oscillations

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Solution Overview

Problem

Existing control systems for aircraft with elastic structures face challenges in managing structural oscillations due to uncertainties in model complexity and high power consumption, leading to potential instabilities.

Innovation Solution

An adaptive control method that detects oscillations using sensor data and control signal analysis, adjusting the control signal's bandwidth to avoid exciting structural oscillations, leveraging natural damping properties of the aircraft.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If an active controller is used to damp structural oscillations, then oscillation reduction is achieved, but controller complexity and model dependency increase

Engineering Contradiction:
Improvestructural oscillationsVSAvoidcontroller complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent implements feedback by continuously monitoring control signals for oscillatory patterns and automatically adjusting controller gains to suppress detected oscillations. The controller receives feedback about system behavior and adapts its parameters in real-time, reducing dependency on precise structural models while maintaining effectiveness.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent dynamically changes controller parameters (gains) based on detected oscillation characteristics. By monitoring the frequency and amplitude of oscillations in control signals and sensor data, the controller adjusts its parameters to counteract resonant frequencies, reducing structural oscillations without requiring a complete structural model.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If controller gains are increased to damp oscillations, then oscillation reduction is achieved, but power consumption increases

Engineering Contradiction:
Improvestructural oscillationsVSAvoidpower consumption
Core Design Contradiction:
Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent employs dynamic adjustment of controller gains rather than static high gains. The controller continuously adapts its parameters based on real-time detection of oscillation frequencies and amplitudes, applying energy only when and where needed to damp oscillations, thereby minimizing overall power consumption while maintaining effectiveness.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The controller monitors its own output signals and automatically adjusts its parameters to prevent oscillations. By detecting oscillatory patterns in its own control signals and sensor feedback, the system self-regulates to suppress resonant frequencies without requiring external intervention or excessive energy input.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If complex structural models are used in the controller, then oscillation damping accuracy is improved, but system robustness decreases due to model uncertainties

Engineering Contradiction:
Improveoscillation detection accuracyVSAvoidsystem robustness
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent uses feedback from actual sensor measurements and control signal monitoring to adapt controller parameters in real-time. This reduces dependency on pre-defined structural models by continuously learning from actual system behavior, improving robustness against model uncertainties while maintaining oscillation detection accuracy through direct measurement.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The controller dynamically changes its parameters based on detected oscillation characteristics rather than relying on fixed model-based parameters. By adapting gains and frequencies based on real-time sensor data and control signal analysis, the system maintains accuracy without requiring a precise structural model, thereby improving robustness.

Inventive Principle:
Principle #35Parameter changes

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 effectively reduces structural oscillations with reduced complexity and power requirements, maintaining system stability without introducing new dynamics that could destabilize the control system.

Implementation Method 1

Mechanical structures are never perfectly rigid. There is always some level of elasticity within an elastic structure or between different mechanical systems

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

Said forces and torques can be applied to the system in various ways... structural oscillations due to structural elasticity or various elastic connections present within the system

Methodology Applied
Scientific EffectDamping: Damping

Data Source

PatentEP3819209B1Method of operating an aircraft and aircraft operable accordingly
Publication Date: 2023.03.29 VOLOCOPTER GMBH
  • EP3819209B1 patent drawingFigure 1
  • EP3819209B1 patent drawingFigure 2
  • EP3819209B1 patent drawingFigure 3

AI summary

We disclose a method of operating a system, for example an aircraft (1), said system comprising a structure (5) made from a plurality of structural parts (5a-5d) interconnected via a plurality of mechanical connections, which parts and connections present inherent elasticity, said system further comprising at least one actuator, for example a propulsion unit (3), which actuator is mechanically attached to said structure (5) and which actuator is controlled by means of a control signal (ui) generated by a control unit (2), said system further comprising at least one sensor unit (4) for measuring a physical property of the system, the method comprising, during system operation, a) detecting a first oscillation in an output signal of the sensor unit (4); b) detecting a second oscillation in the control signal (ui), preferably on a computed control signal and, if available, on actuator states; c) comparing said first oscillation and said second oscillation; d) based on the comparison in step c), adapting a property of the control signal.