Browsing by Subject "Sensors"

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3D Printed Functional Materials and Devices and Applications in AI-powered 3D Printing on Moving Freeform Surfaces
(2020-08) Zhu, Zhijie
The capability of 3D printing a diverse palette of functional inks will enable the mass democratization of manufactured patient-specific wearable devices and smart biomedical implants for applications such as health monitoring and regenerative biomedicines. These personalized wearables could be fabricated via in situ printing --- direct printing of 3D constructs on the target surfaces --- at ease of the conventional fabricate-then-transfer procedure. This new 3D printing technology requires functional (e.g., conductive and viscoelastic) inks and devices (e.g., wearable and implantable sensors) that are compatible with in situ printing, as well as the assistance of artificial intelligence (AI) to sense, adapt, and predict the state of the printing environment, such as a moving hand and a dynamically morphing organ. To advance this in situ printing technology, this thesis work is focused on (1) the development of functional materials and devices for 3D printing, and (2) the AI-assisted 3D printing system. To extend the palette of 3D printable materials and devices, on-skin printable silver conductive inks, hydrogel-based deformable sensors, and transparent electrocorticography sensors were developed. As with the AI for in situ 3D printing, solutions for four types of scenarios were studied (with complexity from low to high): (1) printing on static, planar substrates without AI intervention, with a demonstration of fully printed electrocorticography sensors for implantation in mice; (2) printing on static, non-planar parts with open-loop AI, with a demonstration of printing viscoelastic dampers on hard drives to eliminate specific modes of vibration; (3) printing on moving targets with closed-loop and predictive AI, with demonstrations of printing wearable electronics on a human hand and depositing cell-laden bio-inks on live mice; (4) printing on deformable targets with closed-loop and predictive AI, with demonstrations of printing a hydrogel sensor on a breathing lung and multi-material printing on a phantom face. We anticipate that this convergence of AI, 3D printing, functional materials, and personalized biomedical devices will lead to a compelling future for on-the-scene autonomous medical care and smart manufacturing.
Analysis of Single Frequency, Carrier Phase Based GPS Positioning Performance and Sensor Aiding Requirements
(Intelligent Transportation Systems Institute, Center for Transportation Studies, University of Minnesota, 2013-01) Gebre-Egziabher, Demoz; Mokhtarzadeh, Hamid
The work described in this report outlines the design and testing of a low-cost, single frequency, carrier phase positioning system. Furthermore, aiding sensor accuracy requirements are analyzed to improve the robustness of the carrier phase system after emerging from signal outages. The applications of interest are ones with safety-of-life implications such as driver assist systems.
Bridge Health Monitoring and Inspections – A Survey of Methods
(Minnesota Department of Transportation, 2009-09) Gastineau, Andrew; Johnson, Tyler; Schultz, Arturo
Since the collapse of the I-35W bridge in August 2007, bridge health monitoring has become an area of intense interest. This report defines terminology related to bridge health monitoring and provides a general glossary of available monitoring systems. The glossary is meant to help readers make an informed decision by understanding how different systems function and their strengths and weakness. The authors developed a questionnaire to send to commercial companies offering monitoring systems. Of the 72 questionnaires that were sent to commercial companies, 38 companies responded and are included in this report. From information provided with these questionnaires, available commercial systems are briefly summarized. Criteria for system evaluation were developed to help the bridge owner narrow down company choices for bridge application. After the owner answers a set of questions pertaining to a particular bridge, a program developed in Microsoft EXCEL helps the bridge owner decide the best system for a particular situation. An example is provided for program clarity. Once company choice is narrowed down, additional criteria were developed to aid in final product choice.
Carbon nanotube based carbon dioxide gas sensors for respiratory monitoring.
(2009-12) Sivaramakrishnan, Shyam
The objective of this work is to create a new sensor for monitoring the concentration of exhaled CO2 gas in human breath. Limitations such as high power, large size, lack of portability and undesirable use of sampling tubes are experienced currently during respiratory CO2 monitoring. CO2 being a very important biomarker, it is desirable to extend the scope of CO2 monitoring beyond clinical use to home and ambulatory monitoring. Due to the vast amount of prior research effort put into currently used non-dispersive infra red (NDIR) CO2 sensors, it was deemed unnecessary to further investigate this technique. The sensor development approach in this thesis has been creation of a solid-state CO2 sensor through merging of state-of-the-art research in different disciplines - namely materials science, nanotechnology, chemistry, mechanical engineering and electrical engineering. Early promise for development of such a sensor is shown by use of functionalized carbon nanotube (CNT) materials. Single-walled carbon nanotubes (SWNTs) functionalized with polyethylene imine (PEI) is used as the CO2 sensitive material. A conductivity measurement technique using surface acoustic wave (SAW) sensors enables measurement of SWNT conductivity with very high resolution. While sensitive to CO2, this embodiment is several times more sensitive to humidity in the environment. Since humidity variation happens simultaneously with CO2 variation in exhaled breath, this is found not to be a viable technique for respiratory CO2 measurement. This early failure suggested a need for a sensor that was equally or more sensitive to CO2 than to other environmental analytes. In looking for such an alternative sensor, a CO2 sensor based on stiffness measurement of bare SWNTs was reported to be sensitive and selective to CO2. However, current techniques used for film-stiffness measurement are too bulky, unreliable or expensive. Hence, a new stiffness sensing transducer is developed using an electret microphone. This stiffness measurement technique is based on the extreme sensitivity of an electret microphone's capacitance to the stiffness of its membrane. A CO2 sensor is obtained by coating such a microphone with SWNTs. This embodiment shows good sensitivity to CO2 but unpredictable response to humidity changes. While some microphones show excellent humidity resistance, others show large response to humidity. This behavior is traced to the fabrication of the microphones. Since commercial microphones are used in this work, it is not possible to control manufacturing specifications. Thus, practical difficulties with obtaining a reliable microphone are a major impediment. It was also judged that the sensitivity of stiffness changes to CO2 might be insufficient for respiratory monitoring. The above two sensor embodiments suggest the difficulty in obtaining a selective yet sensitive solid-state CO2 sensor using carbon nanotubes. Hence, an alternative approach is tested using sensitive, selective but slow commercial CO2 sensors. CO2 sensors made using an electrolytic sensing technique are commercially sold for indoor air-quality monitoring. While reliable, such sensors are too slow for respiratory monitoring. But, development of a (second order) mathematical model for the sensor's slow response enables detection of fast CO2 changes during breathing. This is achieved by inverting the mathematical model to predict the fast CO2 input based on the sensor's slow output. The resulting embodiment is the first reliable respiratory CO2 sensor developed in this work. Though better than NDIR sensors, the power requirements and size of electrolytic CO2 sensors are still unacceptable for portable and wireless respiratory CO2 monitoring. Finally, based on research into CNTs and electrolytic CO2 sensors, a new nanocomposite-material based CO2 sensor is fabricated. This sensor combines advantages of high sensitivity and fast response of CNTs with the selectivity of metal carbonates to CO2. The nanocomposite material is fabricated by attaching nanoparticles of calcium carbonate (CaCO3) to SWNTs. CO2 sensing is achieved by measuring the resistance of the SWNT film which changes due to the reaction between CaCO3 and CO2. Cross-sensitivity to humidity, while present, is small enough to be removed using a reference CNT sensor that does not respond to CO2 but responds to humidity. While reliable in operation, this sensor however suffers from slow response due to chemisorption of CO2 on some of the CNTs. Since resistance of the entire nanocomposite can be controlled by a few CNTs, such slow-responding CNTs cause very poor overall response times (>100s). Model inversion techniques developed earlier are not effective with such response times to predict breath-by-breath CO2 changes. In order to enhance the response time, a capacitance based sensor is developed using a similar nanocomposite (SWNT-BaCO3). This sensor's speed of response is found to be much better compared to the previous embodiment which results in the development of a low-power, small, fast and inexpensive CO2 sensor. However, the sensor's capacitance is still found to be sensitive to environmental humidity. Further, the developed nanocomposites are also found to require humidity in the environment for sensing CO2. Thus, the sensor needs constant humidity to respond to CO2 reliably during breath sensing. This is achieved by completely removing humidity from the exhaled breath (using a molecular sieve) before it reaches the sensor. Simultaneously, humid air sampled away from the face is supplied using a low-power pump to humidify the sensing chamber. Using these designs, a reliable respiratory CO2 sensor is fabricated that is compared with a NDIR CO2 analyzer. Results show that the sensor reliably monitors CO2 concentration in the breath. The developed embodiment could potentially be improved with drift-correcting techniques (hardware and software); but is currently unique in its ability to perform low-power, portable and low-cost respiratory CO2 sensing.
A Comprehensive System for Assessing Truck Parking Availability
(Center for Transportation Studies, University of Minnesota, 2017-01) Morris, Ted; Murray, Dan; Fender, Kate; Weber, Amanda; Morellas, Vassilios; Cook, Doug; Papanikolopoulos, Nikos
Commercial heavy vehicle (CHV) drivers are required under federal Hours of Services (HOS) rules to rest and take breaks to reduce driving while fatigued. CHV drivers and operators must balance compliance to the HOS rules against on-time delivery requirements as well as shorter lead times to plan their trips, thereby making location and parking availability of rest area facilities more critical. Without timely, accurate parking availability information, drivers are left with the dilemma of continuing to drive fatigued, drive beyond HOS CHV operation limits, or park illegally on highway shoulders or ramps—all potential safety hazards. In this study, a multi-view camera system was designed and evaluated to detect truck parking space occupancy in real-time through extensive field operational testing. A system architecture was then developed to disseminate up-to-the-minute truck parking information through three separate information delivery systems: 1) Roadside Changeable Message Signs (CMS), 2) Internet/Website information portal, and 3) an onboard geolocation application. The latter application informs the driver of parking availability of one or more parking facilities that are downstream from their current direction of travel. All three notification mechanisms were evaluated during the field test. Survey studies were conducted to provide feedback from commercial heavy vehicle drivers and operators to better understand their perceptions of parking shortages and utility of the parking information delivery mechanisms. Overall, the system has proven to provide 24/7 around-the-clock per-space parking status with no need for manual interventions to correct detection errors, with per parking space accuracy typically equal to or exceeding 95 percent. The concept of operations field tests demonstrated the feasibility of the technical approach and the potential to alter freight borne trip behaviors by allowing drivers and carriers to plan stops and improve trip efficiency.
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.
Detection of Water and Ice on Bridge Structures by AC Impedance and Dielectric Relaxation Spectroscopy Phase II
(Intelligent Transportation Systems Institute, Center for Transportation Studies, 2013-08) Evans, John F.
During Phase I of this project, we have carried out preliminary evaluation of a novel approach to low-cost sensing systems for monitoring ice, water and deicing solutions on road bridge deck surfaces. Our initial approaches included the techniques of alternating current impedance and dielectric relaxation spectroscopy of responses from simple passive metal sensors. These preliminary results indicated that the second approach of dielectric relaxation spectroscopy was far more promising. Furthermore, likely implementations would be significantly more economical using lower-cost electronics modules connected to passive sensors. Our choice for implementation of dielectric relaxation spectroscopy is based on the measurement of high-frequency components of pulse waveforms reflected from the sensor and using time domain reflectometry (TDR). The information content of these waveforms is strongly influenced by the dielectric properties of the media of interest (ice, water or aqueous solutions of deicing chemicals) in contact with or in close proximity (microns) with passive metal conductors, which comprise the sensor. These high-frequency dielectric relaxation measurements using TDR probe the physical state of precipitation and deicing chemicals on the deck or road surface by the detailed examination of the frequency response waveforms returned after the application of a fast rise-time excitation pulse. Signal processing of the acquired waveforms involves taking the derivative of the response followed by digital filtering and subsequent wavelet analysis to emphasize and distinguished low vs high frequency components of the waveforms reflected from the sensors. Determination of the state and nature of the precipitation, solutions or air in contact with a given sensor is made on a statistical basis via correlation of responses to calibration waveforms collected under known conditions for a given sensor. The software to carry out these signal processing tasks in implemented using LabVIEW.
Detection of Water and Ice on Bridge Structures by AC Impedance and Dielectric Relaxation Spectroscopy, Phases III and IV: Continued Field Testing and Refinement of Novel Water and Ice Sensor Systems on Bridge Decks
(Intelligent Transportation Systems Institute, Center for Transportation Studies, 2013-08) Evans, John F.
During Phases III and IV of this project it was determined that the physical attributes of the prototypes developed during the earlier work was inappropriate for bridge deck installations. Mn/DOT engineers required that they be planar and not require drainage through the deck. As RWIS platforms had been widely deployed on decks throughout the state, we decided to adhere to the RWIS geometric format. This necessitated a significant re-engineering of the sensor hardware before installation and testing at remote bridge sites could proceed. To that end extensive development of a robust sensor meeting these requirements was developed and tested without compromise to the earlier performance results. In large part the maintenance of performance was achieved through a significant modification of the software to include Wavelet analysis of the raw data in the determination of surface state of the sensor platform (ice vs air vs water vs electrolyte present on the sensing electrode structure). The combined regression results for raw TDR responses treated by three analysis procedures are shown to give rise to very reliable results. Unfortunately, remote field testing of sensors installed on bridge decks was not accomplished.
Electrochemical Deposition of Magnetics Based Sensors
(2019-12) Hein, Matthew
Within the context of this thesis, advancements in sensor technology are driven in three separate applications. In each application electrochemistry is used as one of the primary fabrication steps, and magnetic phenomena are sensed in order to convey information about the different systems. The medical device industry is an area where various sensors are seeing increased use. Electromagnetic catheter tracking is an application that depends on high-quality magnetic sensors. The size of the sensor is a significant design constraint in catheters. Investigation of a microfabricated inductive sensor is pursued in chapter 4 of this thesis. High shape anisotropy inductive structures utilizing etched aluminum oxide as electroplating templates are investigated through first-order modeling and fabrication process development. Results show that the AAO is capable of producing high aspect ratio inductive structures though further development would be needed to achieve the consistency in etching required for large scale device fabrication. Biomimetic devices are another area of scientific interest where magnetics can play a role. Electroplated magnetic nanowires can act like large arrays of cilia. In chapter 5, biomimetic nanowire arrays are fabricated into microfluidic channels, and their movement sensed via a magnetic sensor. The nanowires provide a magnetic field that bends as fluid flows through the channel which enables a simple flow measurement through microfluidic channels. Similarly, a low frequency (>10Hz) vibration sensor is demonstrated utilizing a nanowire array above a magnetic sensor. Vibration of the sensor imparts momentum on the nanowires, which bend and leads to a time-varying field. In chapter 6, electrodeposition of Galfenol on a cylindrical surface is demonstrated for the first time. Galfenol has a large magnetostriction constant up to ~400 ppm. Utilizing a rotating cylinder electrode, the parameters to deposit Fe1-xGax films in the x = 15 to 35 range were found. The film's magnetostriction was then demonstrated as part of a torque sensor where magnetic anisotropy was controlled through texturing of the cylinder surface. The effect of magnetic shape anisotropy can be seen to play a significant role in the sensor's output by increasing the sensitivity of the sensor nearly 6x that of the non-textured film.
Enhancement and Field Test Evaluation of New Battery-Less Wireless Traffic Sensors
(Center for Transportation Studies, 2011-10) Pruden, Sean; Vijayaraghavan, Krishna; Rajamani, Rajesh
This project focused on the enhancement of a previous battery-less wireless traffic flow sensor so as to enable it to provide weigh-in-motion (WIM) measurements and provide enhanced telemetry distance. The sensor consists of a 6-feet-long device which is embedded in a slot in the road flush with the pavement. As a vehicle travels over the sensor, vibrations are induced in the sensor. Using piezoelectric elements, energy is harvested from the vibrations and used to power the electronics in the sensor for signal measurements and wireless transmission. The sensor’s performance was evaluated by embedding it in a slot in concrete pavement and driving various vehicles of known weight over it at a number of different speeds on different days. The sensor was found to meet the specification of 500 feet telemetry distance. It was able to provide WIM measurements with an accuracy of better than ±15% in the absence of vehicle suspension vibrations. However, much of the WIM data during the latter period of sensor testing was obtained in the presence of significant suspension vibrations. The project also evaluated the use of 4 consecutive WIM sensors in the road to remove the influence of suspension vibrations.
Improved Approach to Enforcement of Road Weight Restrictions
(Minnesota Department of Transportation, 2013-11) Alexander, Lee; Phanomchoeng, Gridsada; Rajamani, Rajesh
This project focused on the enhancement and evaluation of a battery-less wireless weigh-in-motion (WIM) sensor for improved enforcement of road weight restrictions. The WIM sensor is based on a previously developed vibration energy harvesting system, in which energy is harvested from the vibrations induced by each passing vehicle to power the sensor. The sensor was re-designed in this project so as to reduce its height, allow it to be installed and grouted in an asphalt pavement, and to protect the piezo stacks and other components from heavy shock loads. Two types of software interfaces were developed in the project: a) An interface from which the signals could be read on the MnDOT intranet b) An interface through a wireless handheld display Tests were conducted at MnRoad with a number of test vehicles, including a semi tractor-trailer at a number of speeds from 10 to 50 mph. The sensor had a monotonically increasing response with vehicle weight. There was significant variability in sensor response from one test to another, especially at the higher vehicle speeds. This variability could be attributed to truck suspension vibrations, since accelerometer measurements on the truck showed significant vibrations, especially at higher vehicle speeds. MnDOT decided that the final size of the sensor was too big and could pose a hazard to the traveling public if it got dislodged from the road. Hence the task on evaluation of the sensor at a real-world traffic location was abandoned and the budget for the project correspondingly reduced.
Improved Navigation for Social Robots Through OS and Sensor Augmentation
(2023-07) Bleth, Alexander
The rise in elderly populations requires new innovations to further help combatthe growing population. One innovation that is currently being used is mobile robots to navigate around nursing homes and other medical facilities to further help care workers. One such example of this is the robot Pepper, which is used in nursing homes to navigate to the residents and perform various exercises and therapies. However this model of robot lacks adequate tracking sensors to be able to navigate effectively(Ghit,˘a et al. 2020)(Wauters 2018). To help Pepper map the nursing home for navigation, Pepper was equipped with a LIDAR detector and an NVIDIA Nano(Khan, Zurales, and Kameli 2022). However, the Pepper robot and the Jetson Nano were unable to communicate gracefully due to issues with time synchronization and inaccurate navigation. As such we looked into two solutions to solve this issue. An early solution explored removing the Nvidia Jetson Nano, but due to constraints within Pepper’s OS, it was not accomplished.The second solution used Chrony and NTP to ensure that Pepper and Jetson synced to the same NTP servers and synced to each other. The Jetson changed its timestamp to match Pepper’s; this solution was successful. The navigation files were tuned to function appropriately in a nursing home environment.
Innovative Materials and Advanced Technologies for a Sustainable Pavement Infrastructure
(Minnesota Department of Transportation, 2021-06) Le, Jia-Liang; Marasteanu, Mihai; Zanko, Lawrence M.; Matias de Oliveira, Jhenyffer; Calhoon, Thomas; Turos, Mugurel; Stricherz, Tyler; Hopstock, David M.; Hegg, Vern
It is widely acknowledged that early detection of material damage and timely rehabilitation can lead to a significant reduction in the life-cycle cost of asphalt pavements. This research investigates the capabilities of damage detection and healing of graphite nanoplatelet (GNP)-taconite modified asphalt materials. The first part of the research is concerned with the application of GNP-taconite modified asphalt materials for damage detection using electrical conductivity. It is shown that, as compared to conventional asphalt materials, the GNP-taconite modified asphalt materials exhibit an improved electrical conductivity due to the electron hopping mechanism. Based on the mathematical analogy between the elastostatic field and the electrostatic field, a theoretical model is derived to relate the change of electrical conductivity to the damage extent of the material. Although, in principle, the material damage can be accessed using the electrical conductivity, the practical application of this method is complicated by the fact that the conductivity is influenced by the moisture content. The second part of the research investigates the damage healing capability of GNP-taconite modified asphalt materials heated by microwave. GNP-taconite modified asphalt materials can effectively absorb the heat generated by the microwave, and the rising temperature can effectively heal the microcracks in the binder. This damage-healing mechanism is verified by a set of semi-circular beam tests. Finally, microwave heating technology is applied to the tack coat system. It is shown that, with microwave heating, the GNP-taconite modified asphalt material can effectively improve the bond strength of the interface of the tack coat system.
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.
Low-Cost Portable Video-Based Queue Detection for Work- Zone Safety
(2011-01) Morris, Ted; Schwach, Jory A.; Michalopoulos, Panos G.
Highway work-zone safety is a major concern for government agencies, the legislature, and the traveling public. Several work zone intelligent transportation systems (WZITS) have been developed as a safety countermeasure to warn drivers of dangerous traffic conditions. Unfortunately, the effectiveness of a WZTIS is diminished if the actual traffic flow conditions do not correspond with the sensor information leading to false warnings; these confuse drivers and reduce the credibility of the system, which is often ignored. This can lead to situations where drivers crash into work-zone areas because they are unprepared to stop. The national cost of crashes due to this was estimated to be nearly $2.5 billion. Such “dangerous” traffic conditions are typically characterized by unpredictable queue formations that propagate rapidly into higher speed traffic immediately upstream from the active work zone. False positives or missed warnings could be reduced if the location of queue tails in addition to vehicle speeds in proximity to the active work zone can be accurately detected. In this study, a low-cost rapidly deployable and portable queue detection WZITS warning system is proposed. To demonstrate WZITS feasibility, a queue detection algorithm was designed and tested using widely available, field proven, machine vision hardware that can be integrated into the current portable system prototype, using video data collected in the field from the portable device. The warning trigger generated by the algorithm can then be transmitted to a remote upstream location for triggering roadside emergency warning devices (such as VMS, flashers, etc.).
The Minnesota Bicycle and Pedestrian Counting Initiative: Implementation Study
(Minnesota Department of Transportation, 2015-06) Lindsey, Greg; Petesch, Michael; Hankey, Steve
The Minnesota Bicycle and Pedestrian Counting Initiative: Implementation Study reports results from the second in a series of three MnDOT projects to foster non-motorized traffic monitoring. The objectives were to install and validate permanent automated sensors, use portable sensors for short duration counts, develop models for extrapolating counts, and integrate continuous counts into MnDOT traffic monitoring databases. Commercially available sensors, including inductive loops, integrated inductive loops and passive infrared, pneumatic tubes, and radio beams, were installed both as permanent monitor sites and used for short-duration counts at a variety of locations in cities, suburbs, and small towns across Minnesota. All sensors tested in the study produced reasonably accurate measures of bicycle and pedestrian traffic. Most sensors undercounted because of their inability to distinguish and count bicyclists or pedestrians passing simultaneously. Accuracy varied with technology, care and configuration of deployment, maintenance, and analytic methods. Bicycle and pedestrian traffic volumes varied greatly across locations, with highest volumes being on multiuse trails in urban areas. FHWA protocols were used to estimate annual average daily traffic and miles traveled on an 80-mile multiuse trail network in Minneapolis. Project findings were incorporated in a new MnDOT guidance document, “DRAFT Bicycle and Pedestrian Data Collection Manual” used in statewide training workshops. A major challenge in implementing bicycle and pedestrian traffic monitoring is data management. Years will be required to institutionalize bicycle and pedestrian traffic successfully.
Modelling of galfenol nanowires for sensor applications.
(2010-05) Narayan, Krishnan Shankar
Galfenol is a new magnetostrictive material with potential applications in sensors for acoustic waves. The purpose of the present investigation is to study the properties of galfenol nanowires of nanometer range diameter relevant to sensing of acoustic waves using the phenomenon of magnetostriction. In this endeavor we study first the basic energetics for this material. Then we investigate the macro-scale behaviour for galfenol using the theory of "Large body limits in Ferro-magnetism" of Desimone [DS93]. Subsequently we look at the existence and stability of single domain states in galfenol nanowires. The theoretical predictions are then verified by numerical methods.
Models for Predicting RWIS Sensor Misalignments and Their Causes
(University of Minnesota Center for Transportation Studies, 2010-01) Bhalekar, Prafulla; Crouch, Carolyn J.; Crouch, Donald B.; Maclin, Richard M.
The Minnesota Department of Transportation uses the Road Weather Information System (RWIS) for monitoring the current weather and surface conditions of its highways. The real-time data received from these sensors reduce the need for road patrolling in specific locations by providing information to those responsible for directing winter maintenance operations. Since most road maintenance decisions and weather forecasts are explicitly dependent on the reliability and accuracy of the RWIS sensor data, it is important for one to be able to determine the reliability of the sensor data, that is, to determine whether a sensor is malfunctioning. In a previous project we investigated the use of machine learning techniques to predict sensor malfunctions and thereby improve accuracy in forecasting weather-related conditions. In this project, we used our findings to automate the process of identifying malfunctioning weather sensors in real time. We analyze the weather data reported by various sensors to detect possible anomalies. Our interface system allows users to define decision- making rules based on their real-world experience in identifying malfunctions. Since decision rule parameters set by the user may result in a false indication of a sensor malfunction, the system analyzes all proposed rules based on historical data and recommends optimal rule parameters. If the user follows these automated suggestions, the accuracy of the software to detect a malfunctioning sensor increases significantly. This report provides an overview of the software tool developed to support detection of sensor malfunctions.
A Novel Collision Avoidance System for a Bicycle
(Center for Transportation Studies, University of Minnesota, 2018-04) Jeon, Woongsun; Rajamani, Rajesh
This project focuses on development of a sensing and estimation system for a bicycle to accurately detect and track vehicles for two types of car-bicycle collisions. The two types of collisions considered are collisions from rear vehicles and collisions from right-turning vehicles at a traffic intersection. The collision detection system on a bicycle is required to be inexpensive, small and lightweight. Sensors that meet these constraints are utilized.To monitor side vehicles and detect danger from a right-turning car, a custom sonar sensor is developed. It consists of one ultrasonic transmitter and two receivers from which both the lateral distance and the orientation of the car can be obtained. A Kalman Filter-based vehicle tracking system that utilizes this custom sonar sensor is developed and implemented. Experimental results show that it can reliably differentiate between straight driving and turning cars. A warning can be provided in time to prevent a collision. For tracking rear vehicles, an inexpensive single-beam laser sensor is mounted on a rotationally controlled platform. The rotational orientation of the laser sensor needs to be actively controlled in real-time in order to continue to focus on a rear vehicle, as the vehicle’s lateral and longitudinal distances change. This tracking problem requires controlling the real-time angular position of the laser sensor without knowing the future trajectory of the vehicle. The challenge is addressed using a novel receding horizon framework for active control and an interacting multiple model framework for estimation. The features and benefits of this active sensing system are illustrated first using simulation results. Then, extensive experimental results are presented using an instrumented bicycle to show the performance of the system in detecting and tracking rear vehicles during both straight and turning maneuvers.
The performance and efficiency of hydraulic pumps and motors.
(2010-01) Grandall, David Rossing
This research consists of predicting the performance and efficiency of hydraulic pumps and motors, both with experiments and modeling. A pump and motor test stand is constructed to measure the efficiency of an axial piston swashplate pump/motor unit. A regenerative loop hydraulic system is used to reduce the power requirements of the test stand. The test stand uses an xPC Target data acquisition system. Test conditions focused on low displacement and low speed regimes. Efficiency values ranged from less than 0% to 82%. An existing efficiency model in the literature is fit to the data. Several improvements to the model are suggested. The correlation was satisfactory, but room for improvement still exists. Displacement sensors are recommended in the pump/motor units being tested. This is to avoid the significant uncertainty associated with calculating the derived volume based on the data.

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