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At least 55 records · Page 3

Automated Classification of Vehicle Movements at Signalized Intersections Using Vehicle Trajectories

Accurate vehicle movement classification through signalized intersections is of paramount importance to the analysis of intersection performance and the optimization of traffic control strategies. Conventional techniques for tracking vehicle turning movements depend on infrastructure-based strategies like human counts, loop detectors, and video analytics, all of which are costly, prone to errors, and spatially constrained. High-frequency trajectory data can be utilized to determine vehicle movement patterns in a scalable and infrastructure-independent method due to the adoption of connected vehicles (CVs). In recent years, several studies have utilized connected vehicle data to generate performance measures. Most of the trajectory-based performance measures approaches, however, require map matching-i.e., extracting geospatial references from maps to identify the movements that individual vehicles make at a signalized intersection. These approaches are often time-consuming and hinder scalability since geographic features need to be provided for an analysis to be conducted. Map matching methods are prone to errors as different map versions change these geographic features. This research presents a novel automatic classification pipeline that uses CV trajectory data to classify vehicle movements at signalized crossings, specifically pass-through left-turn and right-turn maneuvers. The process starts by filtering trips that cross a spatial bounding box that has been defined at the target intersection. Approach and departure headings for each trajectory crossing the boundary are computed and are clustered together to identify dominant movements. The proposed algorithm is used to classify the movement of vehicles at 10 intersections in the state of California, and the results indicate that the algorithm can classify movements at these intersections with varying traffic volumes and road network configurations, all in a map-less framework with no need for conflation of vehicle trajectories to a digital base map.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Effect of Angle of Attack on Slope Climbing Performance

Ascending steep slopes is often a very difficult challenge for off-road vehicles, whether on Earth or on extraterrestrial bodies. This challenge is even greater if the surface consists of loose granular soil that does not provide much shear strength. This study investigated how the path at which a vehicle traverses a slope, specifically the angle that it is commanded to drive relative to the base of the hill (the angle of attack), can affect its performance. A vehicle was driven in loose sand at slope angles up to 15 degrees and angles of attack ranging from 10 to 90 degrees. A novel photogrammetry technique was implemented to both track vehicle motion and create a three-dimensional profile of the terrain. This allowed for true wheel sinkage measurements. The study showed that though low angles of attack result in lower wheel slip and sinkage, the efficiency of the vehicles uphill motion increased at higher angles of attack. For slopes up to 15 degrees, a 90 degree angle of attack provided the greatest likelihood of successful ascent.

wheel↗

Excavation on the Moon: Regolith Collection for Oxygen Production and Outpost Site Preparation

The development of a robust regolith moving system for lunar and planetary processing and construction is critical to the NASA mission to the Moon and Mars. Oxygen production may require up to 200 metric tons of regolith collection per year; outpost site development may require several times this amount. This paper describes progress in the small vehicle implement development and small excavation system development. Cratos was developed as a platform for the ISRU project to evaluate the performance characteristics of a low center of gravity, small (0.75m x 0.75m x 0.3m), low-power, tracked vehicle performing excavation, load, haul, and dump operations required for lunar ISRU. It was tested on loose sand in a facility capable of producing level and inclined surfaces, and demonstrated the capability to pick up, carry, and dump sand, allowing it to accomplish the delivery of material to a site. Cratos has demonstrated the capability to pick up and deliver simulant to a bury an inflatable habitat, to supply an oxygen production plant, and to build a ramp.

Caruso, John J.↗

Lunar construction utility vehicle

The lunar construction utility vehicle (LCUV) is an all-purpose construction vehicle which will aid in the robotic assembly of a lunar outpost. The LCUV will have the following capabilities: (1) must be self supporting including repairs; (2) must offload itself from a lunar lander; (3) must be telerobotic and semi-autonomous; (4) must be able to transport one space station common module; (5) must allow for man-rated operation; and (6) must be able to move lunar regolith for site preparation. This study recommends the use of an elastic tracked vehicle. Detailed material analyses of most of the LCUV components were accomplished. The body frame, made of pinned truss elements, was stress analyzed using NASTRAN. A track connection system was developed; however, kinematic and stress analyses are still required. This design recommends the use of hydrogen-oxygen fuel cells for power. Thermal control has proven to be a problem which may be the most challenging technically. A tentative solution has been proposed which utilizes an onboard and towable radiator. Detailed study of the heat dissipation requirements is needed to finalize radiator sizing. Preliminary work on a man-rated cabin has begun; however, this is not required during the first mission phase of the LCUV. Finally, still in the conceptual phases, are the communication, navigation and mechanical arm systems.

Source record↗

More Durable Tracks for Heavy Vehicles

Tie bars instead of threaded fasteners make track throwing less likely. Proposed undercarriage for tank or bulldozer has flanged edges to prevent rocks and other road debris from getting caught in track drive and damaging or casting off track. Improved track has no threaded fasteners to be loosened by road shock and vibration. Continuous chain of floating guide bars articulated at web junctions. Pins replace bolted connections. Guide bars and flanges on vehicle keep out stones.

Collins, Earl R., Jr.↗

A phased array tracking antenna for vehicles

An antenna system including antenna elements and a satellite tracking method is considered a key technology in implementing land mobile satellite communications. In the early stage of land mobile satellite communications, a mechanical tracking antenna system is considered the best candidate for vehicles, however, a phased array antenna will replace it in the near future, because it has many attractive advantages such as a low and compact profile, high speed tracking, and potential low cost. Communications Research Laboratory is now developing a new phased array antenna system for land vehicles based on research experiences of the airborne phased array antenna, which was developed and evaluated in satellite communication experiments using the ETS-V satellite. The basic characteristics of the phased array antenna for land vehicles are described.

Ohmori, Shingo↗

Tracking-station coordinates from Geos 1 and Geos 2 optical flash data.

Center-of-mass coordinates for 28 NASA MOTS and SAO Baker-Nunn camera sites have been obtained from optical flash data from Geos 1 (1965 89A) and Geos 2 (1968 002A). More than 25,000 observations in about 100 two-day arcs were used in dynamical solutions (SAO 1969 AGU gravity model). Comparison of results with local survey solutions and with solutions from deep-space vehicle tracking suggests accuracy of about 2 meters in longitude and height and 5 meters in latitude. The relatively larger error in latitude arose from propagation of gravity-model error largely along the track of these high-inclination satellites. The results have also been compared with the solutions of the SAO 1969 standard earth for station coordinates on the North American datum. The solution obtained in the present work is much closer to the survey results in chord length between stations.

Marsh, J. G.↗

Hyperspectral Imager-Tracker

The Hyperspectral Imager-Tracker (HIT) is a technique for visualization and tracking of low-contrast, fast-moving objects. The HIT architecture is based on an innovative and only recently developed concept in imaging optics. This innovative architecture will give the Light Prescriptions Innovators (LPI) HIT the possibility of simultaneously collecting the spectral band images (hyperspectral cube), IR images, and to operate with high-light-gathering power and high magnification for multiple fast- moving objects. Adaptive Spectral Filtering algorithms will efficiently increase the contrast of low-contrast scenes. The most hazardous parts of a space mission are the first stage of a launch and the last 10 kilometers of the landing trajectory. In general, a close watch on spacecraft operation is required at distances up to 70 km. Tracking at such distances is usually associated with the use of radar, but its milliradian angular resolution translates to 100- m spatial resolution at 70-km distance. With sufficient power, radar can track a spacecraft as a whole object, but will not provide detail in the case of an accident, particularly for small debris in the onemeter range, which can only be achieved optically. It will be important to track the debris, which could disintegrate further into more debris, all the way to the ground. Such fragmentation could cause ballistic predictions, based on observations using high-resolution but narrow-field optics for only the first few seconds of the event, to be inaccurate. No optical imager architecture exists to satisfy NASA requirements. The HIT was developed for space vehicle tracking, in-flight inspection, and in the case of an accident, a detailed recording of the event. The system is a combination of five subsystems: (1) a roving fovea telescope with a wide 30 field of regard; (2) narrow, high-resolution fovea field optics; (3) a Coude optics system for telescope output beam stabilization; (4) a hyperspectral-mutispectral imaging assembly; and (5) image analysis software with effective adaptive spectral filtering algorithm for real-time contrast enhancement.

Agurok, Llya↗

Teleoperated Marsupial Mobile Sensor Platform Pair for Telepresence Insertion Into Challenging Structures

A platform has been developed for two or more vehicles with one or more residing within the other (a marsupial pair). This configuration consists of a large, versatile robot that is carrying a smaller, more specialized autonomous operating robot(s) and/or mobile repeaters for extended transmission. The larger vehicle, which is equipped with a ramp and/or a robotic arm, is used to operate over a more challenging topography than the smaller one(s) that may have a more limited inspection area to traverse. The intended use of this concept is to facilitate the insertion of a small video camera and sensor platform into a difficult entry area. In a terrestrial application, this may be a bus or a subway car with narrow aisles or steep stairs. The first field-tested configuration is a tracked vehicle bearing a rigid ramp of fixed length and width. A smaller six-wheeled vehicle approximately 10 in. (25 cm) wide by 12 in. (30 cm) long resides at the end of the ramp within the larger vehicle. The ramp extends from the larger vehicle and is tipped up into the air. Using video feedback from a camera atop the larger robot, the operator at a remote location can steer the larger vehicle to the bus door. Once positioned at the door, the operator can switch video feedback to a camera at the end of the ramp to facilitate the mating of the end of the ramp to the top landing at the upper terminus of the steps. The ramp can be lowered by remote control until its end is in contact with the top landing. At the same time, the end of the ramp bearing the smaller vehicle is raised to minimize the angle of the slope the smaller vehicle has to climb, and further gives the operator a better view of the entry to the bus from the smaller vehicle. Control is passed over to the smaller vehicle and, using video feedback from the camera, it is driven up the ramp, turned oblique into the bus, and then sent down the aisle for surveillance. The demonstrated vehicle was used to scale the steps leading to the interior of a bus whose landing is 44 in. (.1.1 m) from the road surface. This vehicle can position the end of its ramp to a surface over 50 in. (.1.3 m) above ground level and can drive over rail heights exceeding 6 in. (.15 cm). Thus configured, this vehicle can conceivably deliver the smaller robot to the end platform of New York City subway cars from between the rails. This innovation is scalable to other formulations for size, mobility, and surveillance functions. Conceivably the larger vehicle can be configured to traverse unstable rubble and debris to transport a smaller search and rescue vehicle as close as possible to the scene of a disaster such as a collapsed building. The smaller vehicle, tethered or otherwise, and capable of penetrating and traversing within the confined spaces in the collapsed structure, can transport imaging and other sensors to look for victims or other targets.

Krasowski, Michael J.↗

The interplanetary Pioneers. Volume 2: System design and development

The Pioneer systems, subsystems, and ground support activities are described. Details are given on the launch trajectory and solar orbit plans, spacecraft design approach and evolution, scientific instrument, test and ground support equipment, Delta launch vehicle, tracking and communication, and data processing equipment. Pioneer specifications, and reliability and quality assurance are also included.

Corliss, W. R.↗

Surface soil variability and stratigraphy at the Apollo 16 site

The results of penetration tests, analyses of footprint and Lunar Roving Vehicle track depths, and core tube sample data have been used to deduce details of near-surface stratigraphy (to depths of several tens of cm) and lateral variability in soil conditions. Local variations (meter scale) in penetration resistance and porosity may be large, and soil stratigraphy may be complex. Since average properties are about the same at all sites, these variations probably reflect individual cratering and depositional events. These local variations cannot be anticipated on the basis of surface appearance or behavior.

Mitchell, J. K.↗

Automatic Collection of Rock and Soil Samples

Proposed machine would sample rock or soil automatically. Mounted on a wheeled or tracked vehicle, machine positions drill for cut at any angle from horizontal to vertical, moves power head to drive drill into cut, and stores drilled core in a container. New concept may also be useful in terrestrial agricultural and geologic surveys.

Kyrias, G. M.↗

Automatic Robot Safety Shutdown System

Robot turned off if acceleration exceeds preset value. Signals from accelerometer on robot arm pass through filter and amplifier, eliminating high-frequency noise and hydraulic-pump pulsations. Data digitized and processed in computer. Unit controls other machines that perform repetitive movements, including rotary tables, tracked vehicles, conveyor lines, and elevators.

Lirette, M.↗

Advanced symbology for general aviation approach to landing displays

A set of flight tests designed to evaluate the relative utility of candidate displays with advanced symbology for general aviation terminal area instrument flight rules operations are discussed. The symbology was previously evaluated as part of the NASA Langley Research Center's Terminal Configured Vehicle Program for use in commercial airlines. The advanced symbology included vehicle track angle, flight path angle and a perspective representation of the runway. These symbols were selectively drawn on a cathode ray tube (CRT) display along with the roll attitude, pitch attitude, localizer deviation and glideslope deviation. In addition to the CRT display, the instrument panel contained standard turn and bank, altimeter, rate of climb, airspeed, heading, and engine instruments. The symbology was evaluated using tracking performance and pilot subjective ratings for an instrument landing system capture and tracking task.

Bryant, W. H.↗

Analysis of flexible aircraft longitudinal dynamics and handling qualities. Volume 2: Data

Two analysis methods are applied to a family of flexible aircraft in order to investigate how and when structural (especially dynamic aeroelastic) effects affect the dynamic characteristics of aircraft. The first type of analysis is an open loop modal analysis technique. This method considers the effect of modal residue magnitudes on determining vehicle handling qualities. The second method is a pilot in the loop analysis procedure that considers several closed loop system characteristics. Both analyses indicated that dynamic aeroelastic effects caused a degradation in vehicle tracking performance, based on the evaluation of some simulation results. Volume 2 consists of the presentation of the state variable models of the flexible aircraft configurations used in the analysis applications mode shape plots for the structural modes, numerical results from the modal analysis frequency response plots from the pilot in the loop analysis and a listing of the modal analysis computer program.

Waszak, M. R.↗

Easy-to-Install Link for Track Treads

Link with integral tapered pins proposed as means of joining treads on tracked vehicles. Proposed link saves assembly and maintenance time. Dual pins on link fit into pair of holes on adjacent tread shells. Pins secured by locking clip pressed into grooves on pins.

Collins, Earl R., Jr.↗