Flight Control Algorithm Reducing Fatigue Loads

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Solution Overview

Problem

Rotary-wing aircraft components suffer damage due to high peak loads during aggressive maneuvers, particularly in combat situations, as existing control algorithms are limited in their applicability and focus on specific components rather than overall system design.

Innovation Solution

The Life Improving Control (LIC) algorithm, integrated within a fly-by-wire flight control system, uses a Virtual Load Sensor model to estimate and reduce fatigue loads by modifying flight control system parameters, thereby extending component life without compromising aircraft agility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional physics-based modeling is used for damage classification, then time-frequency damage classification is achieved, but applicability to rotary-wing aircraft flight control system design is limited

Engineering Contradiction:
Improvedamage classification precisionVSAvoidapplicability to rotary-wing aircraft
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent transforms the damage classification approach by changing the modeling parameters from physics-based models to virtual sensor models that directly estimate component loads. This parameter change enables broader applicability to rotary-wing aircraft while maintaining damage classification capability through load estimation rather than physics-based analysis

Inventive Principle:
Principle #35Parameter changes

2Duration of action of stationary object

If control algorithms focus on specific components, then component life is increased, but overall system design applicability is limited

Engineering Contradiction:
Improvecomponent service lifeVSAvoidsystem design applicability
Core Design Contradiction:
Duration of action of stationary objectVSAdaptability or versatility

Solution Approach 1:

The patent creates a universal flight control system that can protect multiple components simultaneously. The virtual sensor model estimates loads on various components (main rotor gearbox, tail rotor drive shaft, etc.) and the control algorithm optimizes maneuvers to reduce peak loads across the entire system, making it applicable to overall system design rather than individual components

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Duration of action of stationary object

If flight control parameters are modified to reduce loads, then component life is extended, but aircraft agility may be compromised

Engineering Contradiction:
Improvecomponent service lifeVSAvoidaircraft agility
Core Design Contradiction:
Duration of action of stationary objectVSSpeed

Solution Approach 1:

The patent implements a dynamic control algorithm that continuously monitors virtual sensor load estimates and adapts control parameters in real-time. The system modifies flight control parameters dynamically during maneuvers to reduce peak loads on components while maintaining aircraft agility through adaptive rather than static parameter changes

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control algorithm uses feedback from virtual sensor load estimates to continuously adjust flight control parameters. By monitoring estimated component loads and responding with appropriate control adjustments, the system extends component life while preserving aircraft performance through closed-loop control rather than open-loop parameter modification

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP2296064B1Life improving flight control system
Publication Date: 2019.04.24 SIKORSKY AIRCRAFT CORP
  • EP2296064B1 patent drawingFigure 1
  • EP2296064B1 patent drawingFigure 2A
  • EP2296064B1 patent drawingFigure 2B~3A

AI summary

A flight control system includes a command model modified in response to a Life Improving Control (LIC) algorithm. An inverse aircraft model is in communication with the command model to generate a flight control system command to command an aircraft state. A feedback path from the command model and the aircraft state is also modified in response to the Life Improving Control (LIC) algorithm.