Browsing by Author "Cheng, Pi-Ming"

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    Advanced BRT Volume I: Innovative Technologies for Dedicated Roadways
    (University of Minnesota Center for Transportation Studies, 2008-06) Alexander, Lee; Cheng, Pi-Ming; Gorjestani, Alec; Menon, Arvind; Newstrom, Bryan; Shankwitz, Craig
    Presented herein is a novel approach to vehicle positioning using RFID technology (Vehicle Positioning System, or VPS). By installing in the road RFID tags encoded with road name or other designation, the specific lane, the direction of travel, and the longitudinal distance from a known reference, a vehicle outfitted with an RFID tag reader can determine its position each time it passes over and reads a tag, thus, providing precisely the information needed for many ITS applications - the longitudinal position of a vehicle in a particular lane on a particular road of the transportation network. Knowledge of lane of travel and distance from a known reference provided by VPS enables many transit applications, including headway control of bus platoons, merge/lane change assistance, rear-end collision avoidance, and bay mark-up applications. For lane assist systems, VPS and a lateral positioning system can augment DGSP in urban areas, providing seamless operation where DGPS accuracy is insufficient for lane keeping. This research focused on designing and building a prototype VPS using existing third party RFID hardware. The hardware was evaluated and characterized to determine if it could be used to create a viable, robust VPS. After the development and characterization of the positioning system, an implementation of a rear-end collision avoidance system was built to demonstrate the use of VPS. Finally, a more sophisticated rear-end collision avoidance system was designed and simulated, after which its implications to the accuracy specifications for VPS were analyzed.
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    Advanced BRT Volume II: Innovative Technologies for Dedicated Roadways
    (University of Minnesota Center for Transportation Studies, 2008-06) Cheng, Pi-Ming; Donath, Max; Gorjestani, Alec; Menon, Arvind; Newstrom, Bryan; Shankwitz, Craig
    Presented herein is a novel approach to vehicle positioning using RFID technology (Vehicle Positioning System, or VPS). By installing in the road RFID tags encoded with road name or other designation, the specific lane, the direction of travel, and the longitudinal distance from a known reference, a vehicle outfitted with an RFID tag reader can determine its position each time it passes over and reads a tag, thus, providing precisely the information needed for many ITS applications – the longitudinal position of a vehicle in a particular lane on a particular road of the transportation network. Knowledge of lane of travel and distance from a known reference provided by VPS enables many transit applications, including headway control of bus platoons, merge/lane change assistance, rear-end collision avoidance, and bay mark-up applications. For lane assist systems, VPS and a lateral positioning system can augment DGSP in urban areas, providing seamless operation where DGPS accuracy is insufficient for lane keeping. This research focused on designing and building a prototype VPS using existing third party RFID hardware. The hardware was evaluated and characterized to determine if it could be used to create a viable, robust VPS. After the development and characterization of the positioning system, an implementation of a rear-end collision avoidance system was built to demonstrate the use of VPS. Finally, a more sophisticated rear-end collision avoidance system was designed and simulated, after which its implications to the accuracy specifications for VPS were analyzed.
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    Bus Rapid Transit Technologies: Assisting Drivers Operating Buses on Road Shoulders: Volume 1
    (2003-12) Alexander, Lee; Cheng, Pi-Ming; Donath, Max; Gorjestani, Alec; Newstrom, Bryan; Shankwitz, Craig; Trach, Walter
    The FTA has identified the concept of Bus Rapid Transit as a means to increase the efficiency of transit operations while maintaining transit's proven safety record. According to the FTA website www.fta.dot.gov, "BRT combines the quality of rail transit and the flexibility of buses. It can operate on exclusive transitways, HOV lanes, expressways, or ordinary streets. A BRT system combines intelligent transportation systems technology, priority for transit, cleaner and quieter vehicles, rapid and convenient fare collection, and integration with land use policy." Because of the limited right-of-way available to build new (and possibly dedicated) lanes for BRT operations, the FTA has identified lane assist as an emerging technology, which will enable deployment of BRT systems. The premise behind lane assist technology is to increase the safety of BRT vehicles as they operate in the more unique environments, such as narrow lanes. Lane assist technology will allow BRT vehicles to operate at the desired higher operating speeds while maintaining the safety of the passengers, BRT vehicle and the motoring public.
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    The Design of a Minimal Sensor Configuration for a Cooperative Intersection Collision Avoidance System - Stop Sign Assist: CICAS-SSA Report #2
    (2010-08) Gorjestani, Alec; Menon, Arvind; Cheng, Pi-Ming; Shankwitz, Craig; Donath, Max
    The deployment of a Cooperative Intersection Collision Avoidance System – Stop Sign Assist (CICAS-SSA) can save lives by addressing the causal factor of crashes at rural thru-Stop intersection: drivers who stop on the minor leg of the intersection, improperly assess the gaps in the traffic on the major leg, proceed, and are then hit. The prototype CICAS-SSA system consisted of a network of sensors covering both the minor and the major legs of the intersection. Sensors on the minor road monitored the approach of vehicles and classified them based on their length and height. Sensors along the major road were arrayed to track vehicles (and the gaps between them) approaching the crossroads from 2000 feet away as a means to ensure that the tracking algorithm had sufficient time to “lock on” and track all approaching vehicles. Because cost is a primary concern for any highway safety application, the development of a “minimal sensor set” which would provide adequate safety performance for minimum cost was paramount to the success of the CICAS-SSA program. This report documents the development of this minimal sensor configuration.
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    Determination of the Alert and Warning Timing for the Cooperative Intersection Collision Avoidance System-Stop Sign Assist Using Macroscopic and Microscopic Data: CICAS-SSA Report #1
    (2010-08) Gorjestani, Alec; Menon, Arvind; Cheng, Pi-Ming; Shankwitz, Craig; Donath, Max
    Crashes at rural thru-stop intersections arise primarily from a driver attempting to cross or enter the mainline traffic stream after failing to recognize an unsafe gap condition. Because the primary cause of these crashes is not failure to stop, but failure to recognize an unsafe condition, the US DOT FHWA, MnDOT, and the University of Minnesota ITS Institute undertook the Cooperative Intersection Collision Avoidance System – Stop Sign Assist (CICAS-SSA) program. CICAS-SSA uses roadside radar sensors, a computer processor and algorithms to determine unsafe conditions, and an active LED icon based sign to provide timely alerts and warnings which are designed to reduce the frequency of crashes at rural expressway intersections. The focus of this report is the alert and warning timing used to provide a driver with assistance in recognizing and taking appropriate action when presented a gap which could be considered unsafe. The work presented herein uses both macroscopic data collected by roadside sensors and data acquisition equipment in Minnesota, Wisconsin, and North Carolina, and microscopic data collected using an instrumented vehicle and test subjects at the Minnesota Research Intersection, located at the intersection of US Hwy 52 and Goodhue County Road 9. Three tenets that are particularly germane to the determination of alert and warning timing for the CICAS-SSA system are: (1) the system does not help a driver choose a safe gap; it is designed to assist a driver with unsafe gap rejection, (2) it indicates when it is unsafe to proceed, not when it is safe to proceed, and (3) it must complement good decision making, and address those instances where poor decision making could lead to a crash.
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    Driver Assistive Systems for Rural Applications: A Path to Deployment, Volume 1
    (2005-08-01) Cheng, Pi-Ming; Gorjestani, Alec; Newstrom, Bryan; Shankwitz, Craig; Trach, Walter
    Deployment of any system is driven by market demand and system cost. Initial deployment of the Intelligent Vehicle Lab Snowplow Driver Assistive System (DAS) was limited to a 45 mile section of Minnesota Trunk Highway 7 west of I-494 and east of Hutchinson MN. To better gage demand and functionality, St. Louis and Polk Counties in Minnesota operationally tested the system during the winter of 2003-2004; Polk County also tested during the winter of 2004-2005. Operational benefits were found to be drastically different in the two counties. Low visibility was not an issue with the St. Louis County snowplow routes, so the system offered few benefits. In contrast the topology of Polk county is flat, with almost no trees. High winds combined with few visual cues create significant low visibility conditions. Polk County was pleased with their original system, and obtained a second system and tested it operationally during the 2004-2005 winter. The experience of these two counties is documented in this volume, Volume One. A key component of the DAS is a high accuracy digital map. With the exception of the mapping process, the present cost of the DAS is well documented. Volume Two describes a system designed to collect and process geospatial data to be used by driver assitive system, and the costs and time associated with collecting map data, and creating a map from that data. With cost data complete, counties can determine whether to acquire these systems.
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    Driver Assistive Systems for Snowplows
    (2003-03-01) Gorjestani, Alec; Alexander, Lee; Newstrom, Bryan; Cheng, Pi-Ming; Sergi, Mike; Shankwitz, Craig; Donath, Max
    A comprehensive driver assistive system which utilizes dual frequency, carrier phase real time kinematic (RTK) differential global positioning system (DGPS), high accuracy digital geospatial databases, advanced automotive radar, and a driver interface with visual, haptic, and audible components has been used to assist specialty vehicle operators perform their tasks under these low visibility conditions. The system is able to provide a driver with high fidelity representations of the local geospatial landscape through a custom designed Head Up Display (HUD). Lane boundaries, turn lanes, intersections, mailboxes, and other elements of the geospatial landscape, including those sensed by automotive radar, are projected onto the HUD in the proper perspective. This allows a driver to safely guide his or her vehicle in low to zero visibility conditions in a desired lane while avoiding collisions. Four areas of research, are described herein: driver assistive displays, the integration of a geospatial database for improved radar processing, snowplow dynamics for slippery conditions, and a virtual bumper based collision avoidance/gang plowing system. (Gang plowing is the flying in formation of snowplows as a means to rapidly clear multilane roads.) Results from this research have vastly improved the performance and reliability of the driver assistive system. Research on the use of a specialized driver assistance system to assist specialty vehicle operators in low visibility conditions, including the design of a custom Head Up Display (HUD) projecting elements of the landscape in proper perspective. Driver assistive displays, the integration of a geospatial database for improved radar processing, snowplow dynamics for slippery conditions, and a virtual bumper based on collision avoidance/gang plowing system are discussed.
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    Inexpensive 2D Optical Sensor for GPS Augmentation
    (Intelligent Transportation Systems Institute, Center for Transportation Studies, University of Minnesota, 2012-12) Cheng, Pi-Ming; Shankwitz, Craig; Arpin, Eddie
    Differential Global Positioning Systems (DGPS) are susceptible to outages due to blocked or missing satellite signals and/or blocked or missing DGPS correction messages. Outages arise primarily due to environmental reasons: passing under bridges, passing under overhead highway signs, adjacent foliage, etc. Generally, these outages are spatially deterministic, and can be accurately predicted. These outages distract drivers using DGPS-based driver assistive systems, and limit the system robustness. Inertial measurements have been proposed as an augmentation for DGPS. Tests have shown that error rates for even emerging technologies are still too high; a vehicle can maintain lane position for less than three to four seconds. Ring laser gyros can do the job, but $100K per axis is still too expensive for road-going vehicles. To provide robust vehicle positioning in the face of DGPS outages, the IV Lab has developed a technique by which a non-contact, 2D true ground velocity sensor is used to guide the vehicle. Although far from fully developed, the system can maintain vehicle position within a lane for GPS outages of up to 20 seconds. New dual frequency, carrier phase DGPS systems generally require less than 20 seconds to acquire a "fix" solution after a GPS outage, so the performance of this system should be adequate for augmentation. Proposed herein is basic research which may lead to the development of an inexpensive, 2D, non-contact velocity sensor optimized for vehicle guidance during periods of DGPS outages.
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    Integration of Infrared Imaging for a Head Up Display Lane Keeping and Collision Avoidance System
    (University of Minnesota Center for Transportation Studies, 2008-06) Cheng, Pi-Ming; Shankwitz, Craig
    A driver assistive system, which uses high accuracy, differentially corrected GPS (DGPS), high-accuracy geospatial databases, radar, computers, and driver interfaces (both a Head Up Display (HUD) and a tactile seat), has been developed to help a driver maintain lane position and avoid collisions during periods of low visibility. These systems have been tested and deployed both in Minnesota and in Alaska. Collision avoidance information is provided to a driver through the HUD. Objects located within the HUD field of view determined to be a threat to a driver are indicated as square boxes. White boxes represent an advisory, and if the detected object is fewer than fifty feet or three seconds from a collision, the box turns to red (a warning). Drivers who have used the system have speculated that a more accurate representation of the object projected on the HUD would make the driving task easier. Emerging Super and High Dynamic Range Cameras (SDRC and HDRC, respectively) appeared to be a feasible, inexpensive means with which to address drivers’ concerns. This report documents the research program. SDRC and HRDC technology failed to meet expectations, but infrared imagery was successfully integrated with the standard HUD.
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    Intersection Decision Support Surveillance System: Design, Performance and Initial Driver Behavior Quantization
    (Minnesota Department of Transportation, 2007-08) Alexander, Lee; Cheng, Pi-Ming; Donath, Max; Gorjestani, Alec; Menon, Arvind; Shankwitz, Craig
    In rural Minnesota, approximately one-third of all crashes occur at intersections. Analysis of crash statistics and reports of crashes at rural expressway through-stop intersections shows that, for drivers who stop before entering the intersection, the majority of crashes involve an error in selecting a safe gap in traffic. The Intersection Decision Support system, developed at the University of Minnesota, is intended to reduce the number of driver errors by providing better information about oncoming traffic to drivers stopped at intersections. This report deals primarily with the surveillance technology which serves as the foundation upon which the IDS system will be built. Three components of the surveillance system are described in detail in the body of the report: 1) a Mainline Sensor subsystem; 2) a Minor Road Sensor subsystem; 3) a Median Sensor subsystem. These subsystems include radar units, laser-scanning sensors, and infrared cameras, integrated with a vehicle tracking and classification unit that estimates the states of all vehicles approaching the intersection. The design, installation, performance, and reliability of each of these three subsystems are documented in the report. The report concludes with an analysis of driver gap acceptance behavior at an instrumented intersection. Gap selection is examined as a function of time of day, traffic levels, weather conditions, maneuver, and other parameters. Log-normal distributions describe gaps acceptance behavior at rural, unsignalized expressway intersections.
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    Macroscopic Review of Driver Gap Acceptance and Rejection Behavior at Rural Thru-Stop Intersections in the US - Data Collection Results in Eight States: CICAS-SSA Report #3
    (2010-08) Gorjestani, Alec; Menon, Arvind; Cheng, Pi-Ming; Newstrom, Bryan; Shankwitz, Craig; Donath, Max
    Crashes at rural thru-stop intersections arise primarily from a driver attempting to cross or enter the mainline traffic stream after failing to recognize an unsafe gap condition. Because the primary cause of these crashes is not failure to stop, but failure to recognize an unsafe condition, the US DOT FHWA, MnDOT, and the University of Minnesota ITS Institute undertook the CICAS-SSA program. CICAS-SSA uses roadside radar sensors, a computer processor and algorithms to determine unsafe conditions, and an active LED icon based sign to provide timely alerts and warnings which are designed to reduce the frequency of crashes at rural expressway intersections. These rural, thru-stop crashes are problems in many states. In conjunction with the CICAS-SSA program, MnDOT and the University of Minnesota led a nine-state (CA, GA, IA, MI, MN, NC, NH, NV, and WI) pooledfund study whereby driver behavior data at rural thru-stop intersections was collected by the Minnesota Mobile Intersection Surveillance System (MMISS). The ultimate goal of the pooled fund study and the analysis of that data described here, was to identify whether drivers in different regions of the county exhibit different gap acceptance/rejection behavior, and if different driver behaviors are identified, determine whether they are different enough to inhibit the deployment of a common CICAS-SSA design throughout the US. The analysis of the data indicated that the system can indeed be deployed nationally.
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    A New Approach to Assessing Road User Charges: Evaluation of Core Technologies
    (2003-09-01) Donath, Max; Shekhar, Shashi; Cheng, Pi-Ming; Ma, Xiaobin
    The main goal of this research was to develop the system requirements for the GPS and the digital map components that make up the core of an in-vehicle road user charging system. The focus was to evaluate both GPS and digital maps in the most difficult of environments - where roads of different jurisdictions and possibly different fee structures are located in close proximity to each other (a highway and a frontage road, for instance). In order for the system to be effective it must be able place the vehicle on the correct road. GPS receivers that are commonly used by automotive navigation systems do not have sufficient accuracy for road user charging applications. However, the GPS-determined positions can be corrected, and thus made more accurate, using publicly and privately available wireless signals, namely, using differential GPS (DGPS). This experimental study, based on road testing, found that only certain DGPS receivers are capable of achieving the needed accuracy. Extensive testing of existing digital maps found that they are also not accurate enough to be used for road user charging. There are however, new, higher accuracy digital maps (not yet publicly available) that are already being used for vehicle safety applications. By combining DGPS and such high accuracy digital maps, the ability to design a road user charging system with high geographical resolution can become a reality.