Browse Topic: Measurements
ABSTRACT This paper presents a novel adaptive sampling method using intelligent UAVs in battlefields to help soldiers with awareness of environments. A UAV can perform as a robotic wingman in soldier formations, compensating for that cannot be scouted by soldiers, even being exposed to enemy fire. With portable size, the UAV is easily carried and flown for scouting tasks anytime. The flexibility of UAVs makes it possible to collect measurements sequentially. Each measurement is adaptively designed and determined from the Bayesian perspective to increase the fidelity of battlefields. Wavelet structure is considered to optimize measurement projections to substantially reduce the number of measurements based on compressive sensing framework. More specifically, each measurement is optimized by maximizing the posterior variance inferred from existing informative data. A motion planning algorithm for UAVs is designed based on the distribution of optimal measurements, striking a balance
ABSTRACT Model based design techniques are being used increasingly to predict vehicle performance before building prototype hardware. Tools like ADAMS and Simulink enable very detailed models of suspension components to be developed so vehicle performance can be accurately predicted. In creating models of vehicle systems, often there is a question about how much component detail or model fidelity is required to accurately model system performance. This paper addresses this question for modeling shock absorber performance by comparing a low fidelity and high fidelity shock absorber model. A high fidelity and low fidelity mathematical model of a shock absorber was developed. The low fidelity shock absorber model was parameterized according to real shock absorber hardware dimensions. Shock absorber force vs. velocity curves were calculated in Simulink. The results from the low fidelity and high fidelity model were compared to shock absorber force vs. velocity test results. New vehicle
ABSTRACT One primary system integration challenge for a terrain measurement system is the triggering and time synchronization of all subsystems. Since individual measurement systems vary in their triggering requirements, both in terms of voltage levels and response times, a comprehensive triggering architecture is difficult to implement. Examples of triggering signal inputs include: a transistor-transistor logic (TTL) compliant signal, an RS-232 compliant signal, and an open/close switch circuit. Pulse-triggering signals are also present, and enable continuous time synchronization between instruments. Therefore, a triggering scheme is proposed capable of accurately initiating, synchronizing, and concluding data collection from multiple sensors and subsystems. Simulation of complete circuit designs show that the trigger circuit is capable of properly processing a single physical switch input signal into a TTL-compliant trigger signal. Synchronization pulse signals are likewise amplified
Abstract: An idealized concept of a v-hull vehicle design for blast analysis has been studied in two different commercial software packages and results are compared to one another. The two software packages are different in nature: one code is an Eulerian Computational Fluid Dynamics (CFD) Finite Volume Solver while the other code is a Lagrangian Finite Element Analysis (FEA) Solver with the ability to couple structures to fluids through a special technique called Arbitrary Lagrangian Eulerian (ALE). The simulation models in this paper have been set up for both CFD and FEA using a commercial pre-processing tool to study the effect of an idealized blast on the vehicle configuration: A pressure blast charge has been placed under the center of the vehicle at the symmetry line. The charge is composed of a prescribed pressure and a temperature pulse in a medium with the properties of air. In the CFD solver, an explicit unsteady solver has been chosen for analysis purposes. This was done
ABSTRACT Design for structural topology optimization is a method of distributing material within a design domain of prescribed dimensions. This domain is discretized into a large number of elements in which the optimization algorithm removes, adds, or maintains the amount of material. The resulting structure maximizes a prescribed mechanical performance while satisfying functional and geometric constraints. Among different topology optimization algorithms, the hybrid cellular automaton (HCA) method has proven to be efficient and robust in problems involving large, plastic deformations. The HCA method has been used to design energy absorbing structures subject to crash impact. The goal of this investigation is to extend the use of the HCA algorithm to the design of an advanced composite armor (ACA) system subject to a blast load. The ACA model utilized consists of two phases: ceramic and metallic. In this work, the proposed algorithm drives the optimal distribution of a metallic phase
ABSTRACT Tools have been developed to compare the dynamic deformation of vehicle hulls as they undergo blast-testing with numerical simulations. These tools allow quantitative comparisons and measurements over a wide area of the hull surface, rather than point comparisons as have been performed in the past. The experimental measurements are performed with the Dynamic Deformation Instrumentation System (DDIS) that was developed for TARDEC. Numerical simulations of the test article attached to Southwest Research Institute’s Landmine Test Fixture were performed with LS-DYNA using an empirical blast-loads model. The specific example highlighted in this paper is the deformation by blast testing of a hull component
ABSTRACT A new integrated testing system for the validation of stochastic vehicle-snow interaction models is presented in this paper. The testing system consists of an instrumented test vehicle, vehicle-mounted laser profilometer and a snow micropenetrometer. The test vehicle is equipped on each tire with a set of 6-axis wheel transducers, and a GPS-based data logger tracks vehicle motion. Data is also simultaneously acquired from the sensors from the test vehicle’s Electronic Stability Program. The test vehicle provides measurements that include three forces and moments at each wheel center, vehicle body slip angle, speed, acceleration, yaw rate, roll, and pitch. The profilometer has a 3-D scanning laser and an Inertial Measurement Unit to compensate for vehicle motion. Depth of snow cover, profile of snow surface and wheel sinkage can be obtained from the profilometer. The snow micropenetrometer measures the strength of the snow cover before and after vehicle traversal. Preliminary
In non-cooperative environments, unmanned aerial vehicles (UAVs) have to land without artificial markers, which is a key step towards achieving full autonomy. However, the existing vision-based schemes have the common problems of poor robustness and generalization, and the LiDAR-based schemes have the disadvantages of low resolution, high power consumption and high weight. In this paper, we propose an UAV landing system equipped with a binocular camera to preform 3D reconstruction and select the safe landing zone. The whole system only consists of a stereo camera, and the innovation of the solution is fusing the stereo matching algorithm and monocular depth estimation(MDE) model to get a robust prediction on the metric depth. The whole landing system consists of a stereo matching module, a monocular depth estimation (MDE) module, a depth fusion module, and a safe landing zone selection module. The stereo matching module uses Semi-Global Matching (SGM) algorithm to calculate the
ABSTRACT The Optical Warhead Lethality Sensor Suite (OWLSS) was designed specifically for tracking dense, fast fragment fields generated in warhead arena testing. OWLSS is an optimized hardware/software solution for measuring correlated properties of detonating warhead fragment distributions. The OWLSS automated track algorithm returns time-dependent 3D position, velocity, size, aerodynamic drag, and mass estimates for each fragment tracked. These data products fill a significant gap in our ability to characterize munitions for weapon effectiveness modeling. Furthermore, the system is modular and can be reconfigured for many tracking applications. In this paper, we present an overview of legacy arena measurement techniques, an overview of the OWLSS optical tracking approach, and we discuss how OWLSS can be employed to collect test data needed to improve the survivability of armored vehicles. Citation: J. P. Burke, Jr, J. Roe, S. F. Henke, B. P. Walker, W. Koons, “An Enhanced Optical
ABSTRACT: Ground vehicle survivability and protection systems and subsystems are increasingly employing sensors to augment and enhance overall platform survivability. These systems sense and measure select attributes of the operational environment and pass this measured “data” to a computational controller which then produces a survivability or protective system response based on that computed data. The data collected is usually narrowly defined for that select system’s purpose and is seldom shared or used by adjacent survivability and protection subsystems. The Army approach toward centralized protection system processing (MAPS Modular APS Controller) provides promise that sensor data will be more judiciously shared between platform protection subsystems in the future. However, this system in its current form, falls short of the full protective potential that could be realized from the cumulative sum of sensor data. Platform protection and survivability can be dramatically enhanced if
ABSTRACT In this context, a damage model is a mathematical algorithm that is used to predict if and when in a given loading history a structure will fail by ductile fracture. Increments in a damage parameter are related to strain increments and state of stress. The damage model would operate as part of a numerical simulation, or separately on an output file. A scale effect in ductile fracture is widely recognized from test data, where a large structure tends to fail at lower strain than a smaller structure that is geometrically similar and of the same material. Most damage models are not scale sensitive, and when they are calibrated to data from small laboratory specimens, they will tend to over-predict the performance (i.e., energy absorbing capability) of a larger structure. Another factor is scatter in test results even when specimens are made with care to be as identical as possible. Both of these factors are addressed in the proposed statistics-based damage model. Scale effects
Pipeline inspection is a crucial aspect of maintaining the integrity, safety, and reliability of the planet’s energy infrastructure. However, due to cost and scale challenges, infrastructure operators struggle to conduct accurate, large-scale inspections. A French startup, HyLight, offers a solution to precisely detect issues on the infrastructure, such as methane leaks on pipelines and defects on power lines at an industrial scale, without emitting greenhouse gases
This SAE Recommended Practice establishes the test procedure, environment, instrumentation, and data analyses for comparing interior sound level of passenger cars, multipurpose vehicles, and light trucks having gross vehicle weight rating (GVWR) of 4540 kg (10 000 lb) or less. The test procedure is characterized by having fixed initial conditions (specified initial vehicle speed and gear selection at the starting point on the test site) to obtain vehicle interior sound measurement during road load operation over various road surfaces at specified constant speeds. The measurement data so derived is useful for vehicle engineering development and analysis
Lasers are essential tools for observing, detecting, and measuring things in the natural world that we can’t see with the naked eye. But the ability to perform these tasks is often restricted by the need to use expensive and large instruments
Airplane turbines and rocket engines are very powerful, hot and noisy and yet in need of extremely sensitive measurement technology. And they have another thing in common: They are most efficient when they run on a constant and even flame. Specialized measurement technology helps aerospace engineers improve combustion chambers and fuel injectors. In Switzerland, two ambitious student organizations have been using iterative pressure measurements to develop and build a significantly more efficient next generation of rocket engines
Solving a decades-old problem, a multi-disciplinary team of Caltech researchers has figured out a method to noninvasively and continually measure blood pressure anywhere on the body with next to no disruption to the patient. A device based on the new technique holds the promise to enable better vital-sign monitoring at home, in hospitals, and possibly even in remote locations where resources are limited
Nanosensors are transforming the field of disease detection by offering unprecedented sensitivity, precision, and speed in identifying biomarkers associated with various health conditions. These tiny sensors, often built at the molecular or atomic scale, can detect minute changes in biological samples, enabling the early diagnosis of diseases such as cancer, infectious diseases, and neurological disorders
Measuring fluid mass in microgravity, where fluid behavior is dominated by fluid properties, is a challenging problem. To address this problem engineers at NASA are developing a capacitance-based, mass-fraction gauge for vessels containing two-phase fluids. The vessel volume is enclosed with an array of electrodes, and a unique set of capacitance measurements of the enclosed volume are made between the electrodes. The capacitance measurements are scaled with appropriate weighting factors derived from Laplace’s Equation to compensate for the highly non-uniform electric fields inside the measurement volume and achieve a greater level of mass fraction accuracy
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