Field studies were conducted in 2005 in Yuma, Arizona at the Yuma Proving Grounds (YPG) to document seismic signatures of walking humans. Walker-generated vertical ground vibrations were recorded using standard omni-directional 4.5 Hz peak-resonance geophones. Walker position and speed were measured using portable GPS equipment.
Collected seismic data were processed and hypothetical sensor performance predictions were made using an algorithm developed for the detection and classification of a walking intruder. Sample results for the Yuma study are presented in the form of sensor detection/classification vs. range plots, and color-coded animations of seismic sensor alarm annunciations during walking intruder tests. A perimeter intrusion scenario for a Forward Operating Base is defined that involves a walker approaching a sensor picket-line along a path exactly halfway between two adjacent sensors. This is considered a conservative representation of the perimeter intrusion problem. Summary plots derived from a binomial probability based analysis define intruder detection probabilities for different sensor spacings. For a 215 lb intruder walking in the Yuma test environment, a 90% probability of at least two walker-classified sensor detections is achieved at a sensor spacing of 140 m.
Preliminary investigations show the intruder classification component of the discussed detection/classification algorithm to perform well at rejecting signals associated with a nearby idling vehicle and normal background noise.
The U.S. Army Engineer Research and Development Center is developing survivability planning and protective measures for base camps. One component of Base Camp Protection/Survivability is sensor-based security. Security designs must cover many configurations, ranging from forward operating bases to the equivalent of fixed facility installations, and be adaptable to changes in mission or base camp layout. Initial emphasis is on identifying sensor systems, such as unattended ground sensors, which can operate reliably at an early stage of base camp development when an intrusion detection capability must be established quickly under austere conditions. Another consideration is portability, so that sensor-secured perimeters can be readily relocated as a base camp evolves in size or configuration. In all cases, security designs will include guidance on the selection, placement, and operation of sensor systems to avoid vulnerabilities that would result when terrain, weather, system performance constraints, and detection zone features and maintenance are overlooked or ignored during the planning and implementation of sensor-based physical security.
The U.S. Army Engineer Research and Development Center Cold Regions Research and Engineering Laboratory is currently developing a human Intruder Thermal Model (ITM) for predicting the average surface temperature of an intruder. ITM provides steady-state predictions of average surface temperature. It accounts for metabolically generated heat and heat exchange with the environment via conduction, convection, perspiration and respiration. It also accounts for long and short-wave radiation exchanges with the environment, the short-wave component being extremely important to daytime surface temperature predictions. Clothing thermal properties and intruder height and weight are factored into model calculations as well.
Operational guidance on reliability as a function of site conditions is essential to unattended ground sensors (UGS) effectiveness. For physical security/force protection sensor systems, the Weather Vulnerability Assessment Tool (WVAT) will fill this need. WVAT is a computer application that will warn of situations in which the likelihood of detecting an intruder falls below a specified probability of detection (Pd). Both Pd and the likelihood of nuisance alarms are predicted for diurnal and seasonal variability in weather, state of the ground, and ground cover. A follow-on computer applications, the Force Protection Sensor Selector, will guide the selection of sensor systems for deployment as a site, based on its prediction of weather-induced variation in site conditions.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.