Cable Tension Estimation Using Laser Scanner Sag Data

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Solution Overview

Problem

Existing methods for inspecting the tension in cables attached to utility poles are inefficient, requiring extensive manual measurements and are prone to errors due to incomplete 3D modeling of cables using Mobile Mapping Systems, leading to potential uneven loads and increased risk of pole damage or failure.

Innovation Solution

A device and method that creates a 3D model of cables using laser scanner data to calculate tension by determining the span and sag, allowing for precise estimation of cable tension even if the cable is not fully modeled, and also assesses the state of utility poles and structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual inspection methods are used to measure cable sag and tension, then measurement precision can be maintained, but inspection cost and time consumption increase significantly

Engineering Contradiction:

Improvecable sag measurement precisionVSAvoidinspection time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces manual mechanical measurement methods with an optical measurement system using a camera and image processing. The system captures images of the cable and uses computer vision algorithms to automatically calculate cable position, sag, and tension, eliminating the need for physical measurement tools and manual calculations while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a virtual 3D model of the cable based on 2D image data. By constructing a catenary curve model that fits the observed cable shape in the image, the system reproduces the cable's spatial configuration digitally, enabling automated tension calculation without physical intervention.

Inventive Principle:

Principle #26Copying

2Extent of automation

If 3D laser scanning is used to create complete cable models, then measurement automation improves, but measurement precision decreases due to incomplete cable capture

Engineering Contradiction:

Improveinspection automationVSAvoidcable tension calculation precision

Core Design Contradiction:

Extent of automationVSMeasurement precision

Solution Approach 1:

The patent recognizes that capturing the entire cable in 3D space is unnecessary. Instead, it uses partial 2D image data of the cable silhouette to infer the complete cable shape through catenary curve fitting. This partial action approach achieves both automation and precision by focusing measurement effort only on visible cable portions.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent replaces physical 3D laser scanning with a 2D optical imaging system combined with mathematical modeling. By substituting mechanical scanning with optical capture and computational geometry, the system achieves higher precision for tension calculation while maintaining full automation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If experienced inspectors perform visual inspection, then measurement precision is maintained, but inspection cost increases due to requirement for specialized expertise

Engineering Contradiction:

Improvecable state assessment accuracyVSAvoidinspection system implementation ease

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent creates a self-service inspection system where the computer algorithm automatically performs measurements and calculations that previously required expert human inspectors. The system autonomously identifies cable features, calculates sag and tension, and generates assessment results without requiring specialized human expertise, thereby reducing costs while maintaining precision.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent substitutes human expert knowledge with an automated computer vision system. By encoding inspection expertise into algorithms for image processing and catenary curve analysis, the system replicates and exceeds human inspector capabilities while eliminating the need for specialized training and reducing operational costs.

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 remote and precise estimation of cable tension, reducing the need for experienced inspectors and minimizing errors, thereby extending the lifespan of poles and reducing inspection costs by accurately identifying potential hazards.

Implementation Method 1

three-dimensional coordinates acquired using a laser scanner

Methodology Applied

Scientific EffectLIDAR (Light Detection and Ranging): LIDAR

Data Source

PatentUS12124777B2Equipment state detection device, equipment state detection method, and program

Publication Date: 2024.10.22 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

An object of the present invention is to provide an equipment state detecting device, an equipment state detecting method, and a program that can create a 3D model of a cable based on three-dimensional coordinates acquired using a laser scanner or the like, and precisely estimate the tension for the entirety of the cable even if the entirety of the cable is not three-dimensionally modeled in the cable model. An equipment state detecting device of the present invention creates a 3D model of a cable based on three-dimensional coordinates acquired using a laser scanner or the like, acquires a sag and a straight line connecting ends of the 3D model based on the 3D model, and calculates the tension of the cable using a known cable load per unit length.