Ground-contacting sensors for seismic landmine detection

Recently, seismic landmine detection techniques have been investigated using ground-contacting sensors to measure ground motion generated by propagating surface waves and their interactions with buried objects such as landmines and clutter. Seismic waves have been generated using both ground-coupled and airborne sources, while non-contact sensors such as radar and laser-Doppler vibrometers have been preferred due to safety concerns. However, ground-contacting sensors can be effectively used provided that the contact with the ground does not adversely affect the propagation of seismic waves, that the sensor to ground coupling is repeatable, and that the sensors have low enough contact force to preclude triggering buried landmines. A ground-contacting sensor has been built with a low-cost commercially available accelerometer in a small lightweight package that ensures consistent coupling to the ground. Design and development of the sensor included experimental testing of several prototypes in a laboratory model, as well as analytical modeling of sensor response. A thirty-two-element line array capable of adjusting to surface contours of up to eight inches was tested at a U. S. Government facility in a temperate climate. The array enabled high-contrast detections of several AT landmines in both dirt and gravel roadbed sites.