Laser Diode Array for Interstory Drift Measurement
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Solution Overview
Problem
There is no widely accepted methodology or technology for reliable and accurate direct measurement of building interstory drift, which is a critical parameter in assessing earthquake response and damage to civil infrastructure.
Innovation Solution
The development of sensor systems that utilize a laser beam source and a diode array to measure interstory drift, where the laser beam is configured to have a width at least two times the diode spacing, allowing for precise measurement of both transient and residual displacements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a narrow laser beam is used to improve spatial resolution, then measurement precision is improved, but the beam may not adequately illuminate multiple diodes for accurate centroid calculation
Solution Approach 1:
The patent changes the beam width parameter to be at least two times the diode spacing width. This parameter adjustment ensures the beam simultaneously illuminates multiple diodes while maintaining measurement precision through centroid calculation, resolving the contradiction between precision and reliability.
2Reliability
If the beam width is increased to illuminate multiple diodes, then measurement reliability is improved, but spatial resolution may deteriorate
Solution Approach 1:
The patent replaces direct mechanical position sensing with optical centroid calculation. By using the relative intensity distribution across multiple illuminated diodes to calculate the beam centroid position, the system achieves high spatial resolution despite using a wider beam, thus resolving the contradiction between reliability and precision.
3Difficulty of detecting and measuring
If direct measurement technology is developed for interstory drift, then measurement capability is improved, but system complexity increases
Solution Approach 1:
The patent introduces a laser beam as an intermediary between the moving structure and the diode array sensor. This optical intermediary enables non-contact measurement of interstory drift, improving measurement capability while keeping the physical sensor system relatively simple and fixed in position.
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 achieves accurate measurement of interstory drift with an error of less than 0.5 mm, enabling reliable assessment of building performance during earthquakes and improving post-earthquake damage assessment and mitigation efforts.
Implementation Method 1
a laser beam source configured to emit a beam... measuring an electrical response (e.g., a voltage and/or induced current) at respective diodes of the plurality of diodes upon which the beam impinges
Data Source
AI summary
Interstory drift measurement systems and methods of using the same can include a laser beam source configured to emit a beam having at least a first width in a first direction and a sensor system comprising a plurality of diodes spaced apart from one another in the first direction. The plurality of diodes can include a first diode and a diode spacing width in the first direction as measured between a centerline of the first diode and a centerline of an adjacent diode of the plurality of diodes in the first direction. The beam width in the first direction is at least two times the diode spacing width.