Aircraft Center-of-Gravity Estimation Using Optical Timing

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Solution Overview

Problem

Current methods for estimating the center-of-gravity and gross weight of an aircraft are inaccurate and restrictive, leading to reduced operational flexibility and payload capacity due to conservative curtailments applied to account for variations in aircraft loading and fueling conditions.

Innovation Solution

A system using a light source and photoelectric sensor to estimate the center-of-gravity by measuring deformities in the aircraft's structural members, such as the nose gear and main landing gear, through timing differences in light beam travel, allowing for more precise weight and center-of-gravity calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual estimation methods are used to determine gross weight and center-of-gravity, then operational simplicity is maintained, but measurement precision deteriorates leading to inaccurate estimates and reduced operational flexibility

Engineering Contradiction:
Improvecenter-of-gravity estimation accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces manual mechanical estimation methods with an optical measurement system. A light source emits light that reflects off reflectors attached to aircraft structural members, and a photoelectric sensor detects the reflected light timing. This optical system substitutes the manual mechanical process, providing automated precise measurement of structural member positions to calculate center-of-gravity location accurately without human intervention.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces reflectors as intermediary elements attached to structural members. These reflectors serve as mediators between the light source and photoelectric sensor, enabling precise detection of structural member positions. The reflectors bounce light back to the sensor, creating a measurable optical path that correlates with the position and deformation of the structural members, thus facilitating accurate center-of-gravity calculation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If conservative curtailments are applied to account for estimation variations, then reliability is improved by ensuring safety margins, but operational flexibility deteriorates due to reduced payload capacity

Engineering Contradiction:
Improvesafety complianceVSAvoidoperational flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements a feedback mechanism where the optical measurement system continuously monitors structural member positions and calculates center-of-gravity location in real-time. This feedback loop provides accurate, up-to-date information about aircraft weight distribution, allowing operators to make informed decisions about payload allocation and loading configurations. The precise feedback eliminates the need for conservative estimates, enabling maximum payload capacity while maintaining safety compliance.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces the mechanical approach of applying conservative curtailments to allowable gross weight and center-of-gravity envelopes with an optical measurement system. By substituting manual estimation with automated optical sensing, the system provides accurate real-time data that eliminates the need for safety margins based on estimation uncertainty, thereby maintaining reliability while maximizing operational flexibility.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If automated optical measurement systems are implemented, then measurement precision is improved for center-of-gravity estimation, but device complexity increases

Engineering Contradiction:
Improveweight and center-of-gravity measurement accuracyVSAvoidoptical system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex manual estimation procedures with a streamlined optical measurement system. The system uses a light source, reflectors attached to structural members, and a photoelectric sensor to automatically measure positions and calculate center-of-gravity. This substitution eliminates the need for manual weighing and calculation processes, providing automated precise measurement despite the introduction of optical components.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses reflectors as simple intermediary elements that facilitate the optical measurement process. These reflectors are attached to structural members and serve as passive mediators that bounce light back to the sensor without requiring power or complex mechanisms. This approach maintains measurement precision while minimizing the complexity added to the system.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 operational flexibility and payload capacity by providing more accurate weight and center-of-gravity estimates, reducing the need for conservative curtailments and increasing the maximum permissible load.

Implementation Method 1

a photoelectric sensor configured to receive a reflected light beam and convert the reflected light beam to a second electrical signal

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP3521177B1Method and device to estimate aircraft information
Publication Date: 2021.02.03 THE BOEING CO
  • EP3521177B1 patent drawingFigure 1
  • EP3521177B1 patent drawingFigure 2
  • EP3521177B1 patent drawingFigure 3

AI summary

A system (100) includes a signal generator (102) that is configured to generate a first electrical signal (130). The system (100) also includes a light source (104) configured to generate a light beam (132) based on the first electrical signal (130). The light source (104) is also configured to direct the light beam (132) towards a structural member (108) of an aircraft (300). The system (100) also includes a photoelectric sensor (112) configured to receive a reflected light beam (134) and convert the reflected light beam (134) to a second electrical signal (136). The reflected light beam (134) corresponds to a portion of the light beam (132) that is reflected from one or more optical reflectors (110) coupled to the structural member (108). The system (100) also includes circuitry (190) configured to estimate a location of a center-of-gravity (XCG) of the aircraft (300) based on a timing difference between the first electrical signal (130) and the second electrical signal (136).