ARL is developing the autonomous capability to directly support the Army's future requirements to employ unmanned
systems. The purpose of this paper is to document and benchmark the current ARL Collaborative Technology Alliance
(CTA) capabilities in detecting, tracking and avoiding moving humans and vehicles from a moving unmanned vehicle.
For this experiment ARL and General Dynamics Robotic Systems (GDRS) conducted an experiment involving an ARL
eXperimental Unmanned Vehicle (XUV) operating in proximity to a number of stationary and moving human surrogates
(mannequins) and moving vehicles. In addition there were other objects along the XUV route of the experiment such as
barrels, fire hydrants, poles, cones, and other clutter.
The experiment examined the performance of seven algorithms using a series of sensor modalities to detect stationary
and moving objects. Three of the algorithms showed promise, detecting human surrogates and vehicles with
probabilities ranging from 0.64 to 0.85, while limiting probability of misclassification to 0.14 to 0.37. Moving
mannequins were detected with slightly higher probabilities than fixed mannequins. The distance from the ground truth
at the time of detection suggests that at a speed of 20 kph with a minimum distance to detection of 19.38 m, the vehicle
would have a minimum of 3.5 seconds to avoid a mannequin or vehicle if detected by one of these three algorithms.
Among mannequins and vehicles and, mannequins were more frequently detected than vehicles.
12 The superior engineering properties of fiber reinforced polymer matrix composites, primarily the high strength-to- weight ratio, make them suitable to applications ranging from sporting goods to aircraft components (e.g. helicopter blades). Unfortunately, consistent fabrication of components with desired mechanical properties has proven difficult, and has led to high production costs. This is largely due to the inability to monitor and control polymer cure, loosely defined as the process of polymer chain extension and cross- linking. Even with stringent process control, slight variations in the pre-polymer formulations (e.g. prepreg) can influence reaction rates, reaction mechanisms, and ultimately, product properties. In an effort to optimize the performance of thermoset composite, we have integrated fiber optic probes between the plies of laminates and monitored cure by Raman spectroscopy, with the eventual goal of process control. Here we present real-time measurements of two high performance aerospace companies cured within an industrial autoclave.
Many of the sensor technologies considered for integration into 'smart' materials systems have been adopted from a host of other applications. Consider, for example, fiber optics; these materials were originally designed for telecommunication and have since been modified to serve as effective sensor elements. The present research, by contrast, has focused on the development of a new generation of sensor specifically designed to meet a range of critical operational constraints. The sensor consists of conductive particles selectively distributed in a non-conductive matrix. The matrix could be an elastometer or the host matrix used in a polymer composite. Selective distribution of the particles allows for unprecedented amplification of the sensor signal, thus augmenting its ability to detect relatively weak disturbances in the host structure. The signals exhibit both analog and digital-like response characteristics, and hence they have been called 'fuzzy' sensors. The advantages of this approach include a practical sensor element that exhibits very low cost (less than 10 centers per sensor), structural compatibility with the host structure, and high sensitivity. The fuzzy sensors have been successfully implemented in a structural composite component and a real time data retrieval system has been developed.
Polymer based piezoelectric composite materials can be readily integrated within laminated composite structures to provide sensing and actuating capabilities. In this study composite films of ferroelectric ceramic/polymer materials have been developed and characterized as in-situ multi purpose sensing elements for the nondestructive monitoring of fiber reinforced composites. In this paper the response of embedded composite films to simulated acoustic emission signals will be presented and discussed. Results show the ability of the composite sensors to detect signals from acoustic emission sources over a wide bandwidth.
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