Browse Topic: Weather and climate
ABSTRACT To advance development of the off-road autonomous vehicle technology, software simulations are often used as virtual testbeds for vehicle operation. However, this approach requires realistic simulations of natural conditions, which is quite challenging. Specifically, adverse driving conditions, such as snow and ice, are notoriously difficult to simulate realistically. The snow simulations are important for two reasons. One is mechanical properties of snow, which are important for vehicle-snow interactions and estimation of route drivability. The second one is simulation of sensor responses from a snow surface, which plays a major role in terrain classification and depends on snow texture. The presented work describes an overview of several approaches for realistic simulation of snow surface texture. The results indicate that the overall best approach is the one based on the Wiener–Khinchin theorem, while an alternative approach based on the Cholesky decomposition is the second
ABSTRACT Autonomous driving is emerging as the future of transportation recently. For autonomous driving to be safe and reliable the perception sensors need sufficient vision in sometimes challenging operating conditions including dust, dirt, and moisture or during inclement weather. LiDAR perception sensors used in certain autonomous driving solutions require both a clean and dry sensor screen to effectively operate in a safe manner. In this paper, UV durable Hydrophobic (UVH) coatings were developed to improve LiDAR sensing performance. A lab testbed was successfully constructed to evaluate UVH coatings and uncoated control samples for LiDAR sensor under the simulated weathering conditions, including fog, rain, mud, and bug. In addition, a mobile testbed was developed in partnership with North Dakota State University (NDSU) to evaluate the UVH coatings in an autonomous moving vehicle under different weathering conditions. These UV-durable easy-to-clean coatings with high optical
ABSTRACT Cold regions are becoming increasingly more important for off-road vehicle mobility, including autonomous navigation. Most of the time, these regions are covered by snow, and vehicles are forced to operate under active snowfall conditions. In such scenarios, realistic and effective models to predict performance of on-board sensors during snowfalls become of paramount importance. This paper describes a stochastic approach for two-dimensional numerical simulation of dynamic snow scenes that eventually will be used for driving condition visualization and vehicle sensor performance predictions. The model captures realistic snow particle size distribution, terminal near-surface particle speeds, and adequately describes interactions with wind. Citation: S. N. Vecherin, M. E. Tedesche, M. W. Parker, “Dynamic Snowfall Scene Simulations for Autonomous Vehicle Sensor Performance”, In Proceedings of the Ground Vehicle Systems Engineering and Technology Symposium (GVSETS), NDIA, Novi, MI
ABSTRACT Evolving requirements for combat vehicles to provide increased mission capability and/or crew safety necessitate the addition of components and add-on armor to currently-fielded vehicles. These new requirements result in increased weight and increased electrical needs, which result in reduced mobility. The APD is built from the ground up to optimize a powertrain solution using cutting-edge technology specifically designed for harsh military environments, for use in both vehicle retrofits and new vehicle designs. The APD combines an efficient 1000 hp engine, transmission, integrated starter generator, thermal management system, and lithium-ion batteries to maximize powerpack power density. The APD was designed for a 45-60 ton combat vehicle, but designing for scalability, reconfigurability, and using modern techniques and technology has allowed the APD to greatly improve the capability and flexibility of the powerpack and the technology can be applied to heavier or lighter
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
ABSTRACT As a continuation of previous collaborative efforts between several US Army organizations and industry leaders which led to the procurement of a National Stock Number (NSN) for a near commercial-off-the-shelf winter tire/wheel assembly for the High Mobility Multipurpose Wheeled Vehicle (HMMWV), this study investigates a low-cost, postproduction modification known as ‘siping’ which may incrementally improve standard tires deployed on the Joint Light Tactical Vehicle (JLTV) in cold regions. Data from engineering tests will quantify performance differences as well as driver feedback from the 11th Airborne Division Soldiers in Alaska show moderate improvement from cutting razor-thin grooves known as ‘sipes’ on conventional winter tire sets. However, Army winter performance specifications developed in 2021 from HMMWV testing quantify greater available improvement to traction available, necessitating further development for winter traction in the JLTV family of tire sets as well as
Abstract The paper will provide representative simulations of particle transport around a vehicle in order to investigate some of the issues related to the accurate prediction of emission and transport of particles induced by a moving vehicle with a transverse blowing wind. Special treatments in boundary conditions and wall law function are discussed and applied to maintain the shape of atmospheric boundary layer wind velocity profile. For the vehicle, we adopt the geometry of a Nissan Pathfinder SUV to study the effects of vehicle emission and transport around a moving vehicle. We perform a set of simulations to better understand the modeling requirements for dust emissions including a sensitivity study to determine the modeling parameters that are most important for accurate modeling of dust generation and transport. In particular, we study the effects of location, size distribution, and initial velocity distributions of the modeled dust emissions on predicted downwind atmospheric
ABSTRACT Seasonality plays a key role in altering the terrain of many military operating environments. Since seasonality has such a large impact on the terrain, it needs to be properly accounted for in vehicle dynamics models. This work outlines a variety of static and dynamic seasonal terrain conditions and their impacts on vehicle mobility in an austere region of Europe. Overall the vehicles performed the best in the dry season condition. The thaw season condition had the most drastic impact on mobility with all but the heavy tracked vehicle being almost completely NOGO in the region. Overall, the heavy tracked vehicle had the best performance in all terrain conditions. These results highlight the importance of incorporating seasonal impacts on terrain into NRMM or any vehicle dynamics model. Future work will focus on collecting more data to improve the empirical relationships between vehicles and seasonal terrain conditions, thereby allowing for more accurate speed predictions
ABSTRACT This paper describes a simulation model for autonomous vehicles operating in highly uncertain environments. Two elements of uncertainty are studied – rain and pedestrian interaction – and their effects on autonomous mobility. The model itself consists of all the essential elements of an autonomous vehicle: Scene -roads, buildings, etc., Environment - sunlight, rain, snow, etc., Sensors - gps, camera, radar, lidar, etc., Algorithms - lane detection, pedestrian detection, etc., Control - lane keeping, obstacle avoidance, etc., Vehicle Dynamics – mass, drivetrain, tires, etc., and Actuation - throttle, braking, steering, etc. Using this model, the paper presents results that assess the autonomous mobility of a Polaris GEM E6 type of vehicle in varying amounts of rain, and when the vehicle encounters multiple pedestrians crossing in front. Rain has been chosen as it impacts both situational awareness and trafficability conditions. Mobility is measured by the average speed of the
ABSTRACT Application of human figure modeling tools and techniques has proven to be a valuable asset in the effort to examine man-machine interface problems through the evaluation of 3D CAD models of workspace designs. Digital human figure modeling has also become a key tool to help ensure that Human Systems Integration (HSI) requirements are met for US Army weapon systems and platforms. However, challenges still exist to the effective application of human figure modeling especially with regard to military platforms. For example, any accommodation analysis of these systems must not only account for the physical dimensions of the target Soldier population but also the specialized mission clothing and equipment such as body armor, hydration packs, extreme cold weather gear and chemical protective equipment to name just a few. Other design aspects such as seating, blast mitigation components, controls and communication equipment are often unique to military platforms and present special
ABSTRACT The department of defense currently uses a number of models of vehicle start batteries with the “6T” form factor. These batteries are typically found in almost every vehicle in the DOD fleet and other systems that require 28VDC power. The use of power and energy on the battlefield is significantly changing and the Warfighter now requires a “start” battery that is used for more than just starting, lighting and ignition (SLI) for the vehicle. Lithium ion battery technologies are showing great promise in addressing these challenges by providing higher power capability for extended silent watch, battery monitoring and extended cycle life. One concern, however, is their ability to operate at low temperatures. One of the most challenging aspects of battery use in military applications is their operation at extreme high and low temperatures. These wide temperature swings can potentially have a dramatic effect on cycle life and performance. One significant concern, especially for
It’s common knowledge that a major challenge for solar energy is how to store excess energy produced when conditions are right, like noon-time sun, so that it can be used later. The usual answer is batteries. But renewable energy resources are causing problems for the electricity grid in other ways as well. In a warm, sunny location like California, mid-afternoon had been a time of peak demand for the electric utility, but with solar it’s now a time of peak output
American drivers have long been accustomed to quickly filling up at a gas station with plenty of fuel available, and electric vehicle drivers want their pit stops to mimic this experience. Driver uncertainty about access to charging during long trips remains a barrier to broader EV adoption, even as the U.S. strives to combat climate change by converting more drivers
Mercedes-Benz has unveiled a pair of prototypes powered by hydrogen combustion engines that were created in collaboration with Mörtlbauer Baumaschinen Vertriebs. The prototypes are part of the “WaVe” development project to research hydrogen combustion engines for special-purpose vehicles. The WaVe project is a publicly funded program by Germany's Federal Ministry for Economic Affairs and Climate Action. It consists of 18 partners ranging from industry and science experts and began in July 2021. Development work on the prototypes began in mid-2022. The main objective of the WaVe project was to develop a hydrogen-based drive system for working machines that demonstrated the practicality of replacing diesel-fueled trucks
The purpose of air conditioning (AC) duct packing is multifaceted, serving to prevent condensation, eliminate rattle noise, and provide thermal insulation. A critical aspect of duct packing is its adhesive quality, which is essential for maintaining the longevity and effectiveness of the packing's functions. Indeed, the challenge of achieving adequate adhesivity on AC ducting parts is significant due to the harsh operating conditions to which these components are subjected. The high temperatures and presence of condensation within the AC system can severely compromise the adhesive's ability to maintain a strong bond. Moreover, the materials used for these parts, such as HDPE, often have low surface energy, which further hinders the formation of a durable adhesive bond. The failure of the adhesive under these conditions can lead to delamination of the duct packing, which can result in customer inconvenience due to rattling noises, potential electrical failures if condensed water
Moisture adsorption and compression deformation behaviors of Semimet and Non-Asbestos Organic brake pads were studied and compared for the pads cured at 120, 180 and 240 0C. The 2 types of pads were very similar in moisture adsorption behavior despite significant differences in composition. After being subjected to humidity and repeated compression to 160 bars, they all deform via the poroviscoelastoplastic mechanism, become harder to compress, and do not fully recover the original thickness after the pressure is released for 24 hours. In the case of the Semimet pads, the highest deformation occurs with the 240 °C-cure pads. In the case of the NAO pads, the highest deformation occurs with the 120 0C-cure pads. In addition, the effect of pad cure temperatures and moisture adsorption on low-speed friction was investigated. As pad properties change all the time in storage and in service because of continuously changing humidity, brake temperature and pressure, one must question any
Sustainability remains a dominant trend in packaging and processing, continuing to attract the attention of the life sciences industry and inspire its new initiatives. Although pharmaceutical and medical device manufacturers must prioritize patient safety and product protection, concerns about climate change, greenhouse gas (GHG) emissions, plastic waste, and pressure to move toward a circular economy are prompting a greater focus on improving the sustainability of their products and packaging
Researchers at the Department of Energy’s Oak Ridge National Laboratory are developing battery technologies to fight climate change in two ways, by expanding the use of renewable energy and capturing airborne carbon dioxide
The ongoing transition from fossil fuels to renewable energy sources has never been more important as climate change and sustainability awareness continue to rise
A new report from Clarivate Plc, London, UK, offers a predictive analysis of high-growth medical technology markets poised to generate over $1 billion in value or achieve double-digit growth within the next five years. The report, “Medical Technologies to Watch in 2024” underscores critical areas of significant investment. Medtech analysts pinpoint five technologies driving substantial clinical and commercial value in devices and diagnostics this year. These innovations hold immense promise for patients, potentially complementing or even supplanting traditional medications and biochemical solutions. Analysts are optimistic that 2024 will bring a more favorable economic climate for medtech competitors, noting that the macro trends remain positive
The transportation sector has an enormous demand for resources and energy, is a major contributor of emissions (i.e., greenhouse gases in particular), and is defined largely by the kind of energy it uses—be it electric cars, biofuel trucks, or hydrogen aircraft. Given the size of this sector, it has a crucial role in combating climate change and securing sustainability in its three forms: environmental, societal, and economic. In this context, there are many questions concerning energy options on the path toward a more sustainable transportation sector. Is hydrogen the fuel of the future? Is there enough electricity to power a fully electric transportation sector? What happens when millions of electric vehicle batteries need to be decommissioned? Which regulatory measures are effective and appropriate for moving the sector in the right direction? What is the “right” direction? This chapter does not aim to answer all those questions. It does, however, highlight and discuss the most
Robots and autonomous vehicles can use 3D point clouds from LIDAR sensors and camera images to perform 3D object detection. However, current techniques that combine both types of data struggle to accurately detect small objects. Now, researchers from Japan have developed DPPFA–Net, an innovative network that overcomes challenges related to occlusion and noise introduced by adverse weather
NASA’s Johnson Space Center is offering an innovative freeze-resistant hydration system for licensing. The technology substantially improves on existing hydration systems because it prevents water from freezing in the tubing, container, and mouthpiece, even in the harshest conditions on Earth
On a cold, sunny day, you’re driving on a rural road, surrounded by snow-covered fields. In an instant, your eyes process the scene, picking out individual objects to focus on — a stop sign, a barn — while the rest of the scene blurs in the periphery. Your brain stores the focused and blurred images as a memory that can be pictured in your mind later, while sitting at your desk
Items per page:
50
1 – 50 of 4003