A photogrammetric solution for measurement of power lines sag via integration of image and accelerometer data of a smartphone

Abstract

Measuring the sag of electrical power transmission cables is an index for sensing their internal tension and safety. In this paper, a simple photogrammetric solution is proposed to measure them which only requires an image taken by a smartphone equipped with an internal accelerometer. In this method, a modified version of the well-known co-linearity condition is proposed and the 3D locus of cables has been modeled with a parabola equation. Accelerometer measurements are used to prevent the ill-posed conditions of unknowns’ estimation and are also contributed to generating the control data for the estimation of unknowns. The distance between the supporting points of cables is the only required control information for this method. The proposed solution, while simple, significantly has reduced the risks and costs of measuring the cable sags. On average, the obtained results indicate a relative accuracy of 2.6% in the estimation of the sags of cables.