Browse Topic: Cartography
ABSTRACT Future autonomous combat vehicles will need to travel off-road through poorly mapped environments. Three-dimensional topography may be known only to a limited extent (e.g. coarse height), but this will likely be noisy and of limited resolution. For ground vehicles, 3D topography will impact how far ahead the vehicle can “see”. Higher vantage points and clear views provide much more useful path planning data than lower vantage points and occluded views from trees and structures. The challenge is incorporating this knowledge into a path planning solution. When should the robot climb higher to get a better view or else continue moving along the shortest path predicted by current information? We investigated the use of Deep Q-Networks (DQN) to reason over this decision space, comparing performance to conventional methods. In the presence of significant sensor noise, the DQN was more successful in finding a path to the target than A* for all but one type of terrain. Citation: E
ABSTRACT To address the need for rapid capture of terrain profiles, and changes in terrain, researchers from Michigan Tech demonstrated a UAS collection system, during a live exercise, supported by the North Atlantic Treaty Organization’s (NATO) Science and Technology Organization (STO). The UAS collection system was deployed to provide high resolution topography (resolution less than 1 cm) with a terrain collection rate greater than 1 meter per second and results were processed within minutes. The resulting topography is of sufficient quality to demonstrate that the technique can be applied to update mobility models, as well as the detection of traverse by ground vehicles
Axles are a prominent part of automotive design. Along with a power transmission and differential system, axles support a vehicle’s weight and road-load reactions. Axles carry different attachments such as brakes and suspensions using brackets. Welds play an important role in design and longevity of bracket assemblies. Welds can be susceptible to fractures caused by intrusions akin to cracks and/or discontinuities, compounded by stress concentration due to weld profile and welding processes. Additionally, the simultaneous optimization of both brackets and welds remains a challenge with limited available methods. While topography or shape optimization techniques can enhance bracket robustness by minimizing compliance as the objective, this approach might inadvertently elevate the likelihood of weld fracture if weld dimensions are not concurrently updated. In this endeavor, compliance is used to improve weld life without affecting bracket robustness by using the Vertex Morphing
When measuring with light, the lateral extent of the structures that can be resolved by an optical imaging system is fundamentally diffraction limited. Overcoming this limitation is a topic of great interest in recent research, and several approaches have been published in this area. In a recent study published in the Journal of Optical Microsystems, a team of researchers from the University of Kassel in Germany presented an approach that uses microspheres placed directly on the surface of the object to extend the limits of interferometric topography measurements for optical resolution of small structures
In an increasingly solar world, the need is growing for economical, large-scale backup systems to provide power when the sun is down and the air is calm. Lithium-ion (Li-ion) batteries are too expensive, and other options — such as pumped hydro — require specific topography that’s not always available
An object hidden below ground has been located using quantum technology — a long-awaited milestone with profound implications for industry, human knowledge, and national security
An analysis of shoreline change, dune volume, beach volume, beach slope, and cumulative elevation change along the northern Outer Banks of North Carolina near the CHL Field Research Facility over a 6-year study period. Army Engineer Research and Development Center, Vicksburg, Mississippi The dynamic nature of the nation's coastlines necessitates frequent shoreline monitoring and mapping. The U.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory (CHL), Field Research Facility (FRF), has collected datasets on the nearshore zone's changing conditions for over 40 years. During the course of these efforts, CHL has continued to develop different technologies to refine shoreline monitoring techniques, with a particular focus on the application of remote sensing technology to coastal monitoring. Light detection and ranging (lidar) scanners have proven useful for the CHL coastal measurement efforts, providing highly detailed data of coastal change and
The dynamic nature of the nation’s coastlines necessitates frequent shoreline monitoring and mapping. The U.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory (CHL), Field Research Facility (FRF), has collected datasets on the nearshore zone’s changing conditions for over 40 years. During the course of these efforts, CHL has continued to develop different technologies to refine shoreline monitoring techniques, with a particular focus on the application of remote sensing technology to coastal monitoring. Light detection and ranging (lidar) scanners have proven useful for the CHL coastal measurement efforts, providing highly detailed data of coastal change and hydro-dynamic processes
Highly autonomous vehicles have drawn the interests of many researchers in recent years. For highly autonomous vehicles, a high-definition (HD) map is crucial since it provides accurate information for autonomous driving. However, due to the possible fast-changing environment, the performance of HD maps will deteriorate over time if timely updates are not ensured. Therefore, this paper studies the updating of lightweight HD maps in closed areas. Firstly, a novel two-layer map model called a lightweight HD map is introduced to support autonomous driving in a flexible and efficient way. Secondly, typical updating of scenarios in closed areas with non-paved roads is abstracted into operations including area border expansion, road addition, and road deletion. Meanwhile, a map updating framework is proposed to address the issue of map updating in closed areas. Finally, an experiment is conducted to demonstrate the feasibility and effectiveness of the proposed map updating approach
A wet clutch model is required in automotive propulsion system simulations for enabling robust design and control development. It commonly assumes Coulomb friction for simplicity, even though it does not represent the physics of hydrodynamic torque transfer. In practice, the Coulomb friction coefficient is treated as a tuning parameter in simulations to match vehicle data for targeted conditions. The simulations tend to deviate from actual behaviors for different drive conditions unless the friction coefficient is adjusted repeatedly. Alternatively, a complex hydrodynamic model, coupled with a surface contact model, is utilized to enhance the fidelity of system simulations for broader conditions. The theory of elastic asperity deformation is conventionally employed to model clutch surface contact. However, recent examination of friction material shows that the elastic modulus of surface fibers significantly exceeds the contact load, implying no deformation of fibers. This article
Sector mesh modeling is the dominant computational approach for combustion system design optimization. The aim of this work is to quantify the errors descending from the sector mesh approach through three geometric modeling approaches to an optical diesel engine. A full engine geometry mesh is created, including valves and intake and exhaust ports and runners, and a full-cycle flow simulation is performed until fired TDC. Next, an axisymmetric sector cylinder mesh is initialized with homogeneous bulk in-cylinder initial conditions initialized from the full-cycle simulation. Finally, a 360-degree azimuthal mesh of the cylinder is initialized with flow and thermodynamics fields at IVC mapped from the full engine geometry using a conservative interpolation approach. A study of the in-cylinder flow features until TDC showed that the geometric features on the cylinder head (valve tilt and protrusion into the combustion chamber, valve recesses) have a large impact on flow complexity. As a
Exposure to carbon monoxide (CO) gas can cause health risks for users of recreational boats and watercraft. Activities such as waterskiing, wakeboarding, tubing, and wakesurfing primarily utilize gasoline engine-driven vessels which produce CO as a combustion by-product. Recent watersports trends show an increase in popularity of activities which take place closer to the stern of the boat (such as wakesurfing) as compared to traditional waterskiing and wakeboarding. Advancements in gas emissions treatment in marine engine exhaust system designs have reduced risks for CO exposure in some boats. This article presents results from on-water testing of three recreational boats, reports average and maximum values of CO levels under various conditions, and exhibits mapping of the density of CO relative to the stern of the test vessels
In-wheel motors offer an optimized solution for novel drivetrain architectures of future electric vehicles that could penetrate into the mainstream automotive industry, moving the wheel actuation where it’s required, directly inside the wheels. Obtainable literature mainly deals with optimization of electromagnetically active parts, however, mechanical design of electromagnetically passive parts that indirectly influence motor performance also requires detailed analysis and extensive validation. To meet the optimal performance requirements (also durable) of an in-wheel traction motor, their mechanical design requires topology optimization of housing elements, thermal mapping, geometrical and dimensional tolerance checks and selection of proper hub bearings, in order to assure consistent electromagnetic behavior stability The following paper uniquely describes the review of loads acting on an in-wheel motor, the workflow of a typical mechanical design process, testing, and validation
Dirt entrance on internal combustion engine's air inlet systems are a common issue to fleet owners. Heavy-duty engines are more susceptible to this due its great air volume aspirated. Aiming to avoid it manufacturers employ increasingly resources to conduct research in the field and to develop more efficient air filtration systems to reduce the probability of this occurs. Anyway, the early diagnosis are the best way to avoid expensive damages to the engine. This study aims to explain how fail due dust aspiration occurs and how to interpret periodic oil analysis in order to preserve the power units and reduce the risk of incorrect diagnosis
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