Object Detection of Ground-Penetrating Radar Signals Using Empirical Mode Decomposition and Dynamic Time Warping

Xi Wu,Christopher Adam Senalik,Xiping Wang,Guanghui Li,James Wacker

doi:10.3390/f11020230

Xi Wu, Christopher Adam Senalik + Show 3 more

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https://doi.org/10.3390/f11020230

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Journal: Forests	Publication Date: Feb 19, 2020
Citations: 9	License type: CC BY 4.0

Affiliation: Jiangnan University, Forest Products Laboratory

Abstract

An object detection method of ground-penetrating radar (GPR) signals using empirical mode decomposition (EMD) and dynamic time warping (DTW) is proposed in this study. Two groups of timber specimens were examined. The first group comprised of Douglas fir (Pseudotsuga menziesii) timber sections prepared in the laboratory with inserts of known internal characteristics. The second group comprised of timber girders salvaged from the timber bridges on historic Route 66 over 80 years. A GSSI Subsurface Interface Radar (SIR) System 4000 with a 2 GHz palm antenna was used to scan these two groups of specimens. GPR sensed differences in dielectric constants (DC) along the scan path caused by the presence of water, metal, or air within the wood. This study focuses on the feature identification and defect classification. The results show that the processing methods were efficient for the illustration of GPR information.

Highlights

Nondestructive testing (NDT) techniques are often applied to evaluate the internal condition of wood structures
The proposed method using empirical mode decomposition (EMD) with Dynamic Time Warping (DTW) was implemented in MATLAB language to analyze the Ground-penetrating radar (GPR) scanning data
This study explicated the effectiveness of using GPR to locate and define the defects of wood timbers, and an object detection method based on EMD and DTW was proposed

Summary

Introduction

Nondestructive testing (NDT) techniques are often applied to evaluate the internal condition of wood structures. Ground-penetrating radar (GPR) technology has been widely used for detecting buried objects of varied materials such as sand, timber, concrete, etc. GPR can detect anomalous electromagnetic responses associated with a variety of significant physical conditions [1]. GPR is a noninvasive geophysical technique for high-resolution imaging and characterization of subsurface media by means of transmitting and receiving high-frequency electromagnetic (EM). Electromagnetic fields that propagate as essentially nondispersive waves were used to detect structures and the changes of material properties within the materials [3]. The waves emitted travels through the material are scattered and/or reflected by changes in impedance, giving rise to events similar to the emitted signal. The variation of two-way travel time, amplitude, or/and frequency of reflection wave are measured by Equation (2) [4]

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