Passive Optical Retroreflector for Bridge Vibration Measurement

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Solution Overview

Problem

Current vibration measurement methods for large structures like bridges are inefficient, as they either require lengthy measurements with laser Doppler velocimeters or frequent battery replacements with wireless sensor nodes, necessitating a solution that can quickly measure vibrations across the entire structure with reduced maintenance.

Innovation Solution

A vibration visualizer system comprising an optical member with a movable mirror and fixed mirrors, which changes the reflection intensity of light or electromagnetic waves based on applied acceleration, allowing for rapid visualization and measurement of vibrations without power-consuming components, enabling quicker analysis and reduced maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If laser Doppler velocimeter is used to measure vibration of bridge, then measurement precision is improved, but measurement time increases significantly

Engineering Contradiction:

Improvevibration measurement precisionVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical laser Doppler velocimeter system with a passive optical retroreflector system. The retroreflector changes light reflection intensity in response to structural vibration, eliminating the need for active mechanical scanning and enabling simultaneous full-field vibration measurement, thus reducing measurement time while maintaining precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transitions from point-by-point measurement in one dimension to full-field simultaneous measurement by utilizing the spatial distribution of multiple retroreflectors across the bridge surface. This dimensional expansion allows comprehensive vibration analysis without sequential measurement delays

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Loss of information

If wireless sensor nodes are attached to measurement object, then vibration data collection is improved, but maintenance frequency increases due to battery replacement

Engineering Contradiction:

Improvevibration data collectionVSAvoidmaintenance frequency

Core Design Contradiction:

Loss of informationVSEase of repair

Solution Approach 1:

The patent replaces active wireless sensor nodes with passive optical retroreflectors that require no power source. The retroreflectors passively modulate reflected light intensity according to structural vibration, eliminating battery replacement needs while continuing to provide comprehensive vibration data collection

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The retroreflector system is self-powered by ambient or illumination light sources, converting optical energy directly into vibration information without requiring external power supply or maintenance. The system serves itself by using the illumination source already present in the measurement environment

Inventive Principle:

Principle #25Self-service

3Measurement precision

If optical member is designed with movable section for retroreflection, then sensitivity to vibration is improved, but device complexity increases

Engineering Contradiction:

Improvevibration sensitivityVSAvoidoptical member structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent incorporates a movable section in the optical member that dynamically adjusts its position or orientation in response to vibration. This dynamic component enables the retroreflector to modulate reflected light intensity according to vibration amplitude, enhancing sensitivity while maintaining relatively simple overall structure through targeted mobility rather than complex mechanisms

Inventive Principle:

Principle #15Dynamics

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 quicker detailed analysis of vibrations across entire structures like bridges, reducing maintenance needs and costs, while maintaining accuracy and sensitivity to vibrations, even from a distance.

Implementation Method 1

an optical member including a fixed section to be fixed to a measurement object; and a movable section movably supported by the fixed section such that a first positional relationship between the fixed section and the movable section is changed by application of an acceleration to the fixed section in a predetermined direction. The optical member changes a reflection intensity of light or electromagnetic wave reflected in a retroreflection direction

Methodology Applied

Scientific EffectRetroreflection: Retroreflector

Data Source

PatentUS10240971B2Vibration visualizer, vibration measurement system, and vibration measurement method

Publication Date: 2019.03.26 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A vibration visualizer comprising an optical member including a fixed section to be fixed to a measurement object; and a movable section movably supported by the fixed section such that a first positional relationship between the fixed section and the movable section is changed by application of an acceleration to the fixed section in a predetermined direction. The optical member changes a reflection intensity of light or electromagnetic wave reflected in a retroreflection direction according to a change of the first positional relationship. The first positional relationship in a stationary state where the acceleration is not applied to the fixed section and the first positional relationship is maintained constant, is different from the first positional relationship most suitable for retroreflection.