Browsing by Author "Palmer, Matthew"

Now showing 1 - 6 of 6
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    4U Lighting – Cooperative Headlighting
    Palmer, Matthew; Tsuda, Hiroshi; Williams, Brian M.; Gibbons, Ronald B. (National Surface Transportation Safety Center for Excellence, 2019-10-31)
    The purpose of this project was to evaluate the effectiveness of an alternative cooperative headlighting method, dubbed 4U Lighting. A human-subjects study was conducted in which 12 participants 65 or older observed pedestrians under different lighting configurations and identified the moment when they were sure they could see a pedestrian. The participants drove a vehicle towards a static vehicle in the opposite lane around which the pedestrians were located. The distance at which participants could detect the pedestrian, termed the detection distance, was compared across lighting conditions and served as the measure of improvement in driver visual performance (visibility). Commercial connected vehicle hardware and protocols were used to communicate position between the two vehicles and to trigger the operation of the custom lighting control system. The system operated as expected and the data showed benefits to driver visual performance.
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    Connected Vehicle Applications for Adaptive Overhead Lighting (On-demand Lighting)
    Gibbons, Ronald B.; Palmer, Matthew; Jahangiri, Arash (Connected Vehicle/Infrastructure University Transportation Center (CVI-UTC), 2016-07-01)
    The Virginia Tech Transportation Institute (VTTI) has developed an on-demand roadway lighting system and has tested the system’s effect on driver visual performance. On-demand roadway lighting can dramatically reduce energy usage while maintaining or increasing vehicle and pedestrian safety. The system developed by VTTI uses connected vehicle technology (CVT), wireless lighting controls, LED luminaires, and a stand-alone processor on the Virginia Smart Road to sense vehicles and turn on roadway lighting only when needed. During this research project, the use of on-demand, or just-in-time, lighting was investigated with respect to assessing driver distraction, and to human factors, including a driver’s ability to visually detect and recognize on-road objects and pedestrians. The developed on-demand lighting system described above utilized dedicated short range communication (DSRC), connected vehicle infrastructure (CVI), and centralized wireless lighting controls, and was used with VTTI-developed in-vehicle instrumentation and custom software. The software allowed the study of forward preview time in terms of forward lighting distance needed for drivers to detect roadside pedestrians and hazards. Visual performance testing revealed a relationship between speed and the amount of forward lighting needed to detect pedestrians and hazards on the side of the roadway, and a small, but statistically insignificant, practical difference in visual performance between on-demand lighting and continuously-on lighting conditions. A survey of participant reactions indicated that the public generally accepts on-demand lighting and does not find it distracting as long as a minimum lighting condition is met. The survey also found that participants felt the system provided a safe driving environment. The main application for an on-demand lighting system would be on roadways with little traffic at night and higher accident rates, or higher conflict areas such as intersections, pedestrian crossings, and merge areas.
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    Crosswalk Lighting Using Narrow Beam Illuminator
    Palmer, Matthew; Bhagavathula, Rajaram; Kassing, Andrew (National Surface Transportation Safety Center for Excellence, 2022-12-09)
    This project’s main objective was to collect and analyze preliminary data regarding the safety benefits of additional narrow beam crosswalk lighting in a naturalistic environment. Experiment participants operated vehicles while confederate pedestrians (child-sized mannequins) were staged at various positions with or without overhead lighting and crosswalk lighting that used a commercially available narrow beam LED (light emitting diode) luminaire. Salex loaned the crosswalk lighting illuminator (CWI) luminaires to the Virginia Tech Transportation Institute for the experiment. When used with overhead lighting, the CWI increased the detection distance of the confederate pedestrians in the crosswalk to 297 m while only increasing the power consumption by 5%. This was nearly double the 160-m detection distance for the highest illuminance overhead only baseline condition. The experiment showed no benefit to using the CWI lighting alone. The results reaffirm that the direction of lighting is significant, but it is only one factor. Merely increasing light levels may not increase visual performance, just as changing the direction may not increase performance. The difference in the location of the illuminators and the overhead lights results in the light coming from different directions and illuminating the pedestrians and the background (roadway) differently than either alone. The effect on pedestrian contrast should be investigated further before setting illuminance levels for CWI lighting. Even with that caveat, the addition of a narrow beam CWI improves driver visual performance at detecting pedestrians in a midblock crosswalk by 88%. This is a powerful finding that should be considered as a safety treatment for midblock crosswalks.
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    Kinematics of beam flexure four-bar linkages with applications in a compound bow
    Palmer, Matthew (Virginia Tech, 1996)
    This thesis is a study in the application of kinematics coupled with elastic body mechanics. Most studies in kinematics assume all mechanism links to be inelastic. Furthermore, the methods of kinematic synthesis have generally been developed to meet requirements of displacement, velocity and acceleration. The work presented in this thesis differs in two important aspects. First, one grounded link of a four-bar linkage is replaced by a cantilevered beam in flexure to produce a force generating mechanism. Second, the synthesis method presented here allows the generation of these mechanisms in closed form for prescribed force generation. A compound archery bow that incorporates four-bar linkages has been developed as an example. This design relies on the non-linear mechanical advantage of the four-bar linkage and the bow mechanics to provide a resistance curve that is more compatible with the human strength curve. In addition, by modifying the bow kinematics, more potential energy can be stored, and thus potentially more kinetic energy can be transferred to the arrow than with previous bows.
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    Traffic Sign Characteristics for Machine Vision Safety Benefits
    Kassing, Andrew; Gibbons, Ronald B.; Li, Eric; Palmer, Matthew; Hamen, Johann; Medina, Alejandra (National Surface Transportation Safety Center for Excellence, 2024-07-03)
    Machine vision has become a central technology for the development of automated driving systems and advanced driver assistance systems. To support safe navigation, machine vision must be able to read and interpret roadway signs, which provide regulatory, warning, and guidance information for all road users. Complicating this task, transportation agencies use a large variety of signs, which can have significantly different shapes, sizes, contents, installation methods, and retroreflectivity levels. Additionally, many environmental factors, such as precipitation, fog, dew, and lighting, also affect the visibility and legibility of roadway signs. Understanding how environmental factors and sign conditions affect machine vision performance will be important for transportation agencies to maximize the technology’s safety benefits. Research began by conducting a literature review cataloguing current research concerning roadway sign and visual performance, vehicle vision systems, and sign significance for automated driving. Information and insight gained during the literature review process informed the design and system development of data collection systems. Field data collection was then performed over the course of 3 months in late spring to early summer in 2021. Simultaneously, sign data were harvested using Google Street View and mapped using ArcGIS. Data collected during the experimental trips were then reduced and carefully prepared for analysis. Researchers conducted a thorough data analysis, particularly looking at sign location, viewing distance, sign color, font size, sun position, and illumination, to assess the impact of many environmental and infrastructure factors on the legibility of sign characters. Results showed that blue and brown signage with white legend text provided the best chance of sign character legibility during the daytime; sign characters were easy to read during the day at all three experimental distances (200, 400, and 500 ft), with small characters becoming less legible as view distance increased; daytime legibility decreased as light levels decreased; sign images captured at nighttime illumination levels had poor legibility results; sign characters on overhead signage were found to be more legible and are expected to be identified at a higher rate by vehicle vision systems; and vehicle vision systems should use a high-quality camera capable of taking pictures at night without motion blur.
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    Weather Camera
    Palmer, Matthew; Gibbons, Ronald B. (National Surface Transportation Safety Center for Excellence, 2019-11-18)
    Fog- and weather-related visibility reduction is a common cause of multiple-vehicle crashes. Large differential speeds and a tendency of vehicle operators to drive faster than is safe can lead to terrible crashes. Fog can usually be seen on traffic cameras, which are becoming more prevalent on Virginia highways as well as on highways in other states. This project studied the applicability of one approach to using machine vision to measure fog in a realistic environment simulated on the Virginia Smart Road. With the assistance of Dr. Eric Dumont, a leading visibility research from IFSTTAR in France, a machine vision algorithm was applied to video stills captured from a common traffic camera installed on the Smart Road. Machine vision algorithms were used to determine the average loss in visual detail in the scene viewed by the camera and this was used to generate an empirical model relating Meteorological Optical Range (MOR) and the camera images. The model was used to evaluate data captured on days close in time and days over the following year. Finally, the research investigated the approach’s sensitivity to preset positioning errors in the camera. The research shows that the approach has promise. However, further research and development are needed before the approach is ready for deployment.