Browsing by Subject "GPS"
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Item Accuracy and location success of an ultralite GPS unit(University of Minnesota Duluth, 2014) Elfelt, Morgan; Moen, RonaldTechnological advances in GPS tracking units for wildlife have led to smaller and lighter devices. Increased battery life allows for collection of more locations. Before a new device is used in the field, it is important to evaluate its performance in order to more accurately interpret the raw data collected. Our objective was to determine the accuracy and location success of the G10 Ultralite GPS logger for potential use in a study of wood turtles (Glyptemys insculpta). We conducted stationary and moving tests under a variety of device settings and field conditions. For stationary tests, accuracy was measured by calculating the 50% and 95% circular error probable (CEP) at each test location. The CEP is the radius of a circle centered at the true location which contains either 50% or 90% of locations. We also calculated angular dispersion of each dataset, a measure of the direction and concentration of locations. Moving tests were conducted at two sites where wood turtles occur in order to evaluate the GPS unit performance under expected field conditions. Location success was ≥ 95% for all tests, including moving tests, indicating strong potential for consistent performance in the field. Location accuracy was not affected by snapshot size, location interval, or canopy cover. The angular dispersion values calculated indicated little bias in any compass direction, although smaller datasets had greater bias. The 95% CEP for most tests was < 40 m, demonstrating feasibility for assessment of wood turtle movements and habitat use. Integrating use of a temperature sensor would allow for better determination of aquatic vs. terrestrial behavior. To increase accuracy of GPS datasets, data should be screened to identify and remove outliers, using prior knowledge of animal movement characteristics. The high accuracy and location success documented in our tests combined with low power consumption and high storage capacity demonstrates the potential of the G10 Ultralite as an effective animal tracking device.Item The effect of road network structure on speeding using GPS data(2016-05) Yokoo, ToshihiroThis paper analyzes the relationship between road network structure and speeding using GPS data collected from 152 individuals over a 7 day period. To investigate the relationship, we develop an algorithm and process to match the GPS data and GIS data accurately. Comparing actual travel speed from GPS data with posted speed limits, we measure where and when speeding occurs, and by whom. We posit that road network structure shapes the decision to speed. Speeding is large in both high speed limit zones (e.g. 60 mph (97 km/h)) and low speed limit zones (less than 25 mph (40 km/h)); in contrast, speeding is much lower in the 30 - 35 mph (48-56 km/h) zones. The results suggest driving patterns depend on the road type. We also find that if there are many intersections on the road, the average link speed (and speeding) drops. Long links are conducive to speeding.Item Establishing The Feasibility Of Making Fine-Scale Measurements Of Habitat Use By White-Tailed Deer In Northern Minnesota(2020-01) Smith, BradleyAdvances in technology enhance our ability to understand wildlife-habitat relationships. The Minnesota Department of Natural Resources’ new statewide white-tailed deer (Odocoileus virginianus) management plan aims to enhance its ability to maintain regional deer numbers near population goals. Habitat management is acknowledged as a key component to achieving the plan’s objectives. Informed habitat management prescriptions, based on an improved understanding of optimal size, shape, and arrangement of forest stands and foraging sites, and edge relationships, will contribute to a more successful integration of long-term forest and deer habitat management strategies. The objectives of my study were to establish the feasibility of combining cutting-edge Global positioning system (GPS) collar, remote sensing, and Geographic Information System technologies to 1) classify and inventory available habitat on deer winter ranges and 2) characterize how deer use habitat at the stand level to facilitate an improved understanding of their habitat requirements in northern Minnesota. During winter 2017–2018, 20 adult female deer were captured and fitted with GPS collars on 2 study areas (10/site) in northcentral (Inguadona Lake [IN]) and northeastern (Elephant Lake [EL]) Minnesota, with an additional 40 collars (20/site) deployed during winter 2018–2019. Prior to the deployment of GPS collars on free-ranging deer, I conducted stationary tests to evaluate the location-fix-success and spatial accuracy of 48 collars placed in 4 different cover types. The overall mean location error of the GPS collars was 5.7 m (± 0.15, range = 0–189), with errors in dense conifer (10.3 ± 0.52, range = 0–189 m) being greater than in hardwood stands (6.2 ± 0.22, range = 0–91 m), browse patches (3.2 ± 0.08, range = 0–26 m), and openings (3.2 ± 0.08, range = 0–32 m). With incorporation into the collars of quick fix pseudoranging (QFP) programming, I recovered 100% of the location-fixes during the stationary tests and from 30 collars deployed on free-ranging deer. Spatially, dense conifer stands accounted for 21% and 9%, and moderately dense conifer stands for 4% and 10% of the EL and IN sites, respectively. The proportion of forage openings was 9% on both sites. The mean size (area) of available dense conifer stands was similar on both study sites (6.7, 95% CI = 4.94–8.54 ha vs 6.0, 95% CI = 4.68–7.23 ha). Available forest stands were generally circular, providing a larger core area and less edge, with a mean edge:area ratio <400 m/ha. Deer use of cover types was highly variable among individuals. Mean individual use of dense conifer stands was 23% (range = 0–79%) and 9% (range = 0–29%), and mean use of forage openings was 13% (range = 0–42%) and 24% (range = 0–70%) at the EL and IN sites, respectively. To better understand deer use at the stand level and the arrangement of cover types, I measured the distance from each location-fix to the nearest dense conifer stand and forage opening. While using forage openings, deer were a mean of 177 m (± 7, range = 0–833) and 195 m (± 4, range = 0–882) from dense conifer stands at EL and IN. Likewise, individuals using dense conifer stands were a mean of 241 m (± 6, range =0–777) and 147 m (± 8, range =0–1,030) from forage openings at the respective sites. The use of an integrated technological approach is essential to a more thorough understanding of seasonal habitat requirements of deer. The ability to retrieve 100% of location-fixes with high spatial accuracy will allow us to confidently assess winter habitat use by white-tailed deer as winter progresses and assist managers in formulating prescriptions that effectively integrate forest and habitat management strategies and activities.Item GPS FASER Flight 01(2014-09-04) Taylor, BrianItem GPS FASER Flight 03(2014-09-04) Taylor, BrianItem GPS FASER Ground 01(2012-05-31) Taylor, BrianItem GPS FASER Ground 02(2012-05-31) Taylor, BrianItem GPS FASER Ground 08(2012-10-30) Taylor, BrianItem Image Navigation UROP Research(2014-07-23) VandenAvond, SeanItem Individual differences in adolescent and young adult daily mobility patterns and their relationships to big five personality traits: a behavioral genetic analysis.(2022-05) Alexander, JordanYouth behavior changes and their relationships to personality have generally been investigated using self-report studies, which are subject to reporting biases and confounding variables. Supplementing these with objective measures, like GPS location data, and twin-based research designs, which help control for confounding genetic and environmental influences, may allow for more rigorous, causally informative research on adolescent behavior patterns. To investigate this possibility, this study aimed to (1) investigate whether behavior changes during the transition from adolescence to emerging adulthood are evident in changing mobility patterns, (2) estimate the influence of adolescent personality on mobility patterns, and (3) estimate genetic and environmental influences on mobility, personality, and the relationship between them. Twins aged Fourteen to twenty-two (N=709, 55% female) provided a baseline personality measure, the Big Five Inventory, and multiple years of smartphone GPS data from June 2016 - December 2019. Mobility, as measured by daily locations visited and distance travelled, was found via mixed effects models to increase during adolescence before declining slightly in emerging adulthood. Mobility was positively associated with Extraversion and Conscientiousness (r of 0.17 ̶ 0.25, r of 0.10 ̶ 0.16) and negatively with Openness (r of -0.11 ̶ -0.13). ACE models found large genetic (A = 0.56 ̶ 0.81) and small-moderate environmental (C of 0.12 ̶ 0.28, E of 0.07 ̶ 0.15) influences on mobility. A and E influences were highly shared across mobility measures (rg = 0.70, re= 0.58). Associations between mobility and personality were partially explained by mutual genetic influences (rg of -0.27 ̶ 0.53). Results show that as autonomy increases during adolescence and emerging adulthood, we see corresponding increases in youth mobility. Furthermore, the heritability of mobility patterns and their relationship to personality demonstrate that mobility patterns are informative, psychologically meaningful behaviors worthy of continued interest in psychology.Item Mapping Gps Satellite Signal Visibility, Specularity, And Multipath For Improved Urban Navigation(2023-07) Zeller, EmmaGPS has been a key positioning tool since it was first introduced, and improved space and control segments have led users to expect accurate positioning. However, there are still uncertainties and errors in the user segment that can’t be fully accounted for upfront due to challenges specific to each user. GPS positioning in urban environments is challenging as tall buildings often block, reflect, or diffract signals. When signals reflect off buildings or other surfaces they reach the receiver via a non-line-of-sight (NLOS) path. Multipath is a phenomenon that occurs when a signal from a single satellite reaches the receiver via both a direct-line-of-sight (DLOS) and NLOS path. When a strong reflected signal reaches the receiver at a delay less than ~300m relative to the direct path signal, the interference due to the combination of both signals causes errors in the computed position solution. Many techniques in conventional software defined radios (SDRs) equipped to detect multipath attempt to mitigate the resulting errors by removing the NLOS component or the entire signal. However, very few approaches attempt to utilize both the DLOS and NLOS signals as additional measurements to aid in positioning. The approach discussed in this work uses urban mapping to predict visibility and specularity at any location of interest within the mapped environment, as well as the Multipath Estimating Delay Lock Loop (MEDLL) to characterize multipath signals. These are then incorporated into Direct Position Estimation (DPE), an alternative positioning approach that directly computes a multi-dimensional spatial correlogram from the individual satellite correlations, rather than individually tracking each to get a navigation solution. Experimental data from both a stationary and driving experiment done in Denver, CO are used to test the different methods. When positioning results using DPE integrating visibility and specularity predictions from both urban mapping and MEDLL are compared to standard SDR positioning, improvements are seen.Item Merge Assist System Using GPS and DSRC Based Vehicle-to-Vehicle Communication(2019-01) Hussain, ShahOne potential area to improve driver safety and traffic mobility is around merge points of two roadways e.g., at a typical freeway entrance ramp. Due to poor visibility because of weather or complex road infrastructure, on many such entrance ramps, it may become difficult for the driver on the merging/entrance ramp to clearly see the vehicles travelling on the main freeway, making it difficult to merge. A fundamental requirement to facilitate many ADAS functions including a merge assist system is to accurately acquire vehicle positioning information. Accurate position information can be obtained using either sensor-based systems (camera-based, RADAR, LiDAR) or Global Navigation Satellite Systems (GPS, DGPS, RTK). For these systems to work well for practical road and weather conditions, advanced techniques and algorithms are needed which make the system complex and expensive to implement. In this report, the author proposes a merge assist system by acquiring the relative positioning of vehicles using standard GPS receivers and DSRC based V2V communication. The DSRC equipped vehicles travelling on the main freeway and on the entrance-ramp will periodically communicate their positioning information with each other. Using that information, the relative trajectories, relative lane and position of all DSRC equipped vehicles travelling on the main freeway, will be calculated and recorded in real time in the vehicle travelling on the entrance ramp. Finally, a merge time cushion will also be calculated which could potentially be used to assist the driver of the ramp vehicle to safely merge into the freeway.Item Reference Position and Attitude together with Raw Sensor Data from Seven Small UAV Flights during 2011-12(2014-09-09) Mokhtarzadeh, HamidReference trajectory (3D position and attitude) and raw sensor data (at 50 Hz) for seven small UAV flights are included. The flights can be used individually or collectively. Collectively they cover a 1 square kilometer area. The flights were collected over the span of 2011-2012 by the University of Minnesota UAV Research Group and were retrieved for research purposes in 2013-2014. All seven flights have been successfully used to study navigation system design. Through a simulated play-back of the data, both an attitude heading reference system (AHRS) and an airspeed-based dead reckoning navigation system were implemented on all seven flights and the results correspond well with the logged reference solutions. As part of testing new ideas for small UAVs or navigation in general, it is useful to have a data set which has been tried and tested. This subset of flights from the AEM UAV Flight repository is exactly that and is being shared with the hope of serving as a working data set for testing new concepts and ideas.Item Remote sensing using GPS bistatic radar with applications to low earth orbit nanosatellites.(2009-12) Pogemiller, James A.This thesis presents the results of analysis and experiments evaluating the potential for using reflected GPS signals as a remote sensing instrument. Using GPS signals in this manner is, in effect, a bistatic radar that utilizes one of the GPS bands (L1, 1575.42MHz) and has many advantages for small satellite applications because it pro- vides a sensor which is passive, has a small foot print and consumes very little power. The reflected GPS signals can provide information about ocean surface conditions and other information about terrestrial land mass. The GPS bistatic radar also has the potential for being a sensor for relative ranging and proximity sensing on orbit. This is particularly useful because it allows measuring ranges to objects or satellites that are not equipped with a GPS receiver (e.g, a dead satellite or passive target), for a variety of missions including satellite servicing and formation operations.Item Sensor Integration Software(2014-07-23) Murch, AustinItem Small UAV Position and Attitude, Raw Sensor, and Aerial Imagery Data Collected over Farm Field with Surveyed Markers(2015-02-25) Mokhtarzadeh, Hamid; Colten, Todd; mokh0006@umn.edu; Mokhtarzadeh, HamidImagery and sensor data from a commercial small Uninhabited Aerial Vehicle flown over an agriculture field on the morning of October 22, 2014 have been logged and documented. The field includes 16 surveyed ground control points laid out in a 4x4 square serving as known ground control points. This data set serves to study both challenges and opportunities of UAV-based remote sensing for precision agriculture applications. The raw sensor data can be used for navigation system design and analysis. The imagery and logged aircraft state can be used for image processing as well as remote sensing analysis. It is being shared to served as a documented data set for testing new concepts and ideas.Item SmarTrAC: A Smartphone Solution for Context-Aware Travel and Activity Capturing(2015-02) Fan, Yingling; Wolfson, Julian; Adomavicius, Gediminas; Vardhan Das, Kirti; Khandelwal, Yash; Kang, JieThe use of mobile phones in collecting travel behavior data has rapidly increased, especially after GPS tracking technology became widely available in commercial smartphones. Existing smartphone-based tools in the field have generally focused on capturing the “when”, “where”, and “how” of travel, i.e., using the smartphone’s automatic sensing functionality to detect travel mode and to collect position and route data. Although locations and modes of transportation derived from sensing data represent important travel behavior information, travel behavior has many other important dimensions—such as trip purpose, travel experience, and travel companionship (i.e., the “why”, “how”, and “who” of travel)—all of which are critical for understanding people’s travel choices. Some of these dimensions may be inferable from pure sensory data, but reliable inference will generally require long-term use data from a very large number of subjects. Other dimensions are simply inaccessible to passive sensing tools. In contrast, traditional travel diary methods and some first-generation smartphone-based travel survey tools enable the collection of multi-dimensional data through high-intensity sampling and qualitative survey techniques. However, these methods are often burdensome to study subjects and impractical for use in a diverse, mobile, and increasingly time-stressed population.Item Source, Fall 2008(University of Minnesota Extension, 2008) University of Minnesota ExtensionItem Techniques for improving routing by exploiting user input and behavior(2014-10) Torre, FernandoThis dissertation explores innovative techniques for improving the route finding process. Instead of focusing on improving the algorithm itself, I aim to improve the other factors that make the route finding experience better: personalization, map data, and presentation. I do so by making extensive use of user input (both explicit and implicit) and crowdsourcing strategies. This research uses Cyclopath, a geowiki for cyclists in the Twin Cities, MN, as a case study for the various techniques explored.The first challenge is the lack of personalization in route finding algorithms. Aside from start and end points, algorithms usually know very little about users. However, user preferences can greatly affect their ideal routes. I studied the use of community-shared tags that allow users to specify preferences for those tags instead of doing so for each individual road segment, allowing them to easily express preference for a large number of roads with little effort. Correlation between individual road segment ratings and ratings deduced from tag preferences was evidence of the utility of this technique for making personalization easier.The second challenge is missing data. The best routing algorithm is only as good as the map data underneath it. Unfortunately, maps are often incomplete. They might not have updates on the latest construction, might be missing roads in rural areas or might not include detailed information such as lanes, trails, and even shortcuts. I present an HMM-based map matching algorithm that uses GPS traces recorded by users to generate potential new road segments. Tests within Cyclopath confirmed the abundance of missing roads and the ability of this algorithm to detect them.Finally, I look at the issue of unnatural presentation of routes. The way computers relay route directions is very different from humans, who use landmarks most of the time. However, gathering useful landmarks can be difficult and is often limited to points of interest. In this research, I tested methods for crowdsourcing different types of landmarks. I show that POIs are not sufficient to represent landmarks and that there is no objective truth regarding which landmarks are more useful to users.Item Thor Ground 01(2012-05-31) Taylor, Brian