Bridge Displacement Estimation Using Strain and Acceleration

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Solution Overview

Problem

Current methods for estimating bridge displacement rely on visual inspection, which is time-consuming and resource-intensive, and struggle to accurately evaluate crack depth and influence. Additionally, existing frequency domain approaches introduce errors in estimating unknown parameters.

Innovation Solution

A method that uses strain gauges and an accelerometer to generate displacements based on low and high frequency components, with a recursive least square (RLS) algorithm applied to estimate unknown parameters in the time domain, thereby improving accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If visual inspection is used to discover cracks in the bridge, then crack detection is performed, but it requires much time and great human resource

Engineering Contradiction:

Improvecrack detection capabilityVSAvoidinspection time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces manual visual inspection with an automated sensor-based measurement system. Strain gauges and accelerometers are installed on the bridge to automatically measure strain and acceleration, which are then processed to detect cracks and estimate displacement, eliminating the need for manual visual inspection and significantly reducing time and human resource requirements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The bridge structure itself is made to provide measurement data through strain gauges and accelerometers that continuously monitor its condition. The system enables self-diagnosis of crack conditions and displacement states without requiring external manual inspection, allowing the structure to 'report' its own health status automatically.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If frequency domain transformation is used to estimate unknown parameters from strain, then parameter estimation is achieved, but errors are introduced

Engineering Contradiction:

Improveparameter estimation accuracyVSAvoidestimation error

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces frequency domain transformation with time domain correlation analysis. Instead of transforming strain signals to the frequency domain to estimate unknown parameters, the system directly correlates strain and acceleration measurements in the time domain, avoiding the introduction of frequency domain errors while maintaining parameter estimation capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12209935B2Method of estimating displacement of a bridge and an electronic device to estimate displacement of a bridge

Publication Date: 2025.01.28 KOREA ADVANCED INST OF SCI & TECH

AI summary

In a method of estimating displacement of a bridge, a first displacement including a low frequency component and a first high frequency component is generated based on a strain that is measured by a plurality of pairs of strain gauges installed at positions in a first direction from a reference point, in a bridge, a second displacement including a second high frequency component is generated based on an acceleration that is measured by an accelerometer installed at a first position spaced apart from the reference point by a first distance in the first direction, in the bridge, and a final displacement of the bridge is generated based on an unknown parameter associated with the displacement, the low frequency component and the second high frequency component. The unknown parameter is generated by applying a recursive least square algorithm to the first high frequency component and the second high frequency component.