Rotor Blade Height Difference Assessment via Image Analysis

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Solution Overview

Problem

Current methods for balancing rotor blades in rotorcrafts are complex and require costly, wired equipment that needs synchronization with rotor speed, making them difficult to implement in flight and prone to high installation and downtime costs.

Innovation Solution

A method using an image sensor to record successive images of rotating blades, determining trend curves of their trajectories, and evaluating mean deviations to calculate height differences, allowing for adjustments without synchronizing the image acquisition with rotor speed, using a portable device like a smartphone or tablet for image analysis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If synchronized measurement systems with wired equipment are used to measure blade height, then measurement precision is improved, but device complexity increases and ease of operation deteriorates

Engineering Contradiction:
Improveblade height measurement precisionVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical measurement systems (wired sensors, synchronized cameras, stroboscopes) with an optical system using a smartphone camera and image processing algorithms. The mechanical synchronization mechanism is substituted by detecting blade features directly from video frames and calculating height differences through image analysis, eliminating the need for complex mechanical coupling between the measurement system and rotor rotation.

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

Solution Approach 2:

The patent creates a visual copy of the blade trajectory through image capture and processing. Instead of directly measuring physical dimensions with complex sensors, the system captures optical images of the rotating blades, processes these images to extract trajectory information, and calculates height differences from the visual data. This copying approach simplifies the measurement system while maintaining precision.

Inventive Principle:
Principle #26Copying

2Measurement precision

If synchronized measurement systems are installed on the rotor, then measurement precision is improved, but ease of repair worsens due to installation time and downtime costs

Engineering Contradiction:
Improveblade height measurement precisionVSAvoidinstallation and downtime cost
Core Design Contradiction:
Measurement precisionVSEase of repair

Solution Approach 1:

The patent enables the measurement system to be self-contained and portable, allowing operators to perform blade height measurements without requiring installation on the rotor itself. The smartphone-based system can be deployed independently, eliminating the need for technical flight installations and reducing maintenance downtime. The system serves itself by using the smartphone's built-in camera and processing capabilities rather than requiring external specialized equipment installation.

Inventive Principle:
Principle #25Self-service

3Productivity

If in-flight measurements are enabled with wired equipment, then productivity is improved, but device complexity increases due to cable management challenges

Engineering Contradiction:
Improvein-flight measurement capabilityVSAvoidcable and synchronization complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent eliminates mechanical cable connections and physical synchronization mechanisms by using wireless smartphone technology. The system captures video of rotating blades through the aircraft window and performs all processing on the smartphone, replacing wired sensor systems and cable management infrastructure with a portable electronic device that requires no physical connection to the rotor or aircraft systems.

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

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

Enables simple, in-flight balancing of rotor blades by statistically estimating height differences and suggesting adjustments, reducing equipment complexity and installation time, and allowing for efficient rotor balancing without the need for synchronized measurement systems.

Implementation Method 1

using an image sensor, successively recording source images in a space traversed by the rotating blades

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3828081B1Method and device for assessing a difference in height between at least two blades of a rotor, and method for balancing
Publication Date: 2023.05.17 EUROCOPTER FRANCE SA
  • EP3828081B1 patent drawingFigure 1~2
  • EP3828081B1 patent drawingFigure 3~4
  • EP3828081B1 patent drawingFigure 5

AI summary

The present invention relates to a method for evaluating the height difference between at least two blades of a rotor (5) comprising a plurality of rotating blades (6), for example, in the context of rotor balancing. This method comprises at least the following steps: - using an image sensor (15), recording successive source images (60) in a space (40) traversed by said rotating blades (6) during a measurement period; - determining, for each blade (6) with a computer (20), a trend curve of the trajectory of this blade (6) in said space (40) as a function of successive positions of a characteristic point of this blade (6) using each source image (60) containing this blade (6); - evaluating at least one average difference between one trend curve and another trend curve.