Rotor Blade Flapping Measurement Correction for Noise and RPM Drift

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing rotorcraft blade flapping measurement systems are prone to inaccuracies due to susceptibility to random noise and other errors, which affect the precision of flapping angle measurements.

Innovation Solution

A measurement system that includes a rotary variable differential transformer (RVDT) to measure blade flapping, coupled with a processing system that implements correction processes using filter gain and phase compensators, as well as static and tuning correctors, to refine the initial flapping vector and provide a corrected flapping vector, accounting for rotor RPM and torque variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a sensor system is placed proximate to the rotor blades to measure flapping angle, then flapping measurement capability is provided, but measurement precision deteriorates due to susceptibility to random noise and errors

Engineering Contradiction:

Improveflapping angle measurement precisionVSAvoidrandom noise and errors

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary processing system that receives raw flapping measurements from the sensor and applies correction processes. This intermediary system includes algorithms that filter out random noise and errors, transforming the unreliable raw measurements into corrected flapping measurements with improved precision. The processing system acts as a mediator between the noisy sensor and the control system, eliminating the need to improve the sensor hardware itself.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If correction processes are applied to improve measurement accuracy, then measurement precision improves, but device complexity increases due to additional processing components

Engineering Contradiction:

Improveflapping measurement accuracyVSAvoidprocessing system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical correction mechanisms with computational algorithms. Instead of using additional physical sensors, mechanical linkages, or complex hardware-based correction devices, the invention uses software-based correction processes that run on a processing system. This substitution of mechanical/system complexity with computational simplicity achieves measurement precision improvement while minimizing the increase in overall device complexity.

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

The system significantly improves the accuracy of blade flapping measurements by filtering out errors and adjusting for operational modes, leading to more precise control and operation of rotorcraft.

Implementation Method 1

A rotorcraft is disclosed including a rotary variable differential transformer (RVDT) for measuring blade flapping

Methodology Applied

Scientific EffectVariable differential transformer:

Data Source

PatentEP3932802B1Improved blade flapping measurement process

Publication Date: 2022.12.14 TEXTRON INNOVATIONS INC

Figure 1a~1b
Figure 2a
Figure 2b

AI summary

A rotorcraft (10) comprising a rotor blade (26a) designed to flap about a hinge point, a measurement system (200) designed to measure blade flapping, and a processing system (300) designed to alter blade flapping measurements. The processing system further comprises a correction process to alter a blade flapping measurement dependent on rotor RPM or rotor torque.