Non-intrusive ground-contacting vibrometer for acoustic/ seismic landmine detection

Abstract

The detection of buried landmines using seismic waves and full wave-field measurements has been demonstrated. The technique requires a sensor that is non-intrusive with sufficient fidelity, reproducibility, and noise immunity for imaging processes. This has been accomplished in the past with non-contact techniques. For reasons of cost and scalability in large arrays, ground-contacting sensors are currently of interest as an alternative to these. A ground-contacting sensor configuration was studied in which an accelerometer was coupled to the ground through a viscoelastic layer with a bias force provided by a soft coil spring. This sensor was found to meet the noise, fidelity, and reproducibility requirements of a seismic landmine detection system operating in a laboratory experimental model. The fidelity of this sensor was found to vary with the bias force because of the nonlinear stiffness of the soil surrogate in the model. This dependence was sufficiently weak that no feedback of the bias force was necessary to reproducibly couple the sensor over a flat surface. The sensor offers the potential benefit of information that was not available from non-contact measurements regarding the in-plane motion of the soil surface. This data may provide additional cues for the detection of buried mines. [Work supported by ONR.]