7,199 research outputs found
Map-aided navigation for emergency searches
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordReal-time positioning of emergency personnel has
been an active research topic for many years. However, studies on
how to improve navigation accuracy by using prior information
on the idiosyncratic motion characteristics of firefighters are
scarce. This paper presents an algorithm for generating pseudo
observations of position and orientation based on standard search
patterns used by firefighters. The iterative closest point algorithm
is used to compare walking trajectories estimated from inertial
odometry with search patterns generated from digital maps. The
resulting fitting errors are then used to integrate the pseudo
observations into a map-aided navigation filter. Specifically, we
present a sequential Monte Carlo solution where the pattern
comparison is used to both update particle weights and create
new particle samples. Experimental results involving professional
firefighters demonstrate that the proposed pseudo observations
can achieve a stable localization error of about one meter, and
offer increased robustness in the presence of map errors
Security of GPS/INS based On-road Location Tracking Systems
Location information is critical to a wide-variety of navigation and tracking
applications. Today, GPS is the de-facto outdoor localization system but has
been shown to be vulnerable to signal spoofing attacks. Inertial Navigation
Systems (INS) are emerging as a popular complementary system, especially in
road transportation systems as they enable improved navigation and tracking as
well as offer resilience to wireless signals spoofing, and jamming attacks. In
this paper, we evaluate the security guarantees of INS-aided GPS tracking and
navigation for road transportation systems. We consider an adversary required
to travel from a source location to a destination, and monitored by a INS-aided
GPS system. The goal of the adversary is to travel to alternate locations
without being detected. We developed and evaluated algorithms that achieve such
goal, providing the adversary significant latitude. Our algorithms build a
graph model for a given road network and enable us to derive potential
destinations an attacker can reach without raising alarms even with the
INS-aided GPS tracking and navigation system. The algorithms render the
gyroscope and accelerometer sensors useless as they generate road trajectories
indistinguishable from plausible paths (both in terms of turn angles and roads
curvature). We also designed, built, and demonstrated that the magnetometer can
be actively spoofed using a combination of carefully controlled coils. We
implemented and evaluated the impact of the attack using both real-world and
simulated driving traces in more than 10 cities located around the world. Our
evaluations show that it is possible for an attacker to reach destinations that
are as far as 30 km away from the true destination without being detected. We
also show that it is possible for the adversary to reach almost 60-80% of
possible points within the target region in some cities
FootSLAM meets adaptive thresholding
The is the author accepted manuscript. The final version is available from IEEE via the DOI in this recordCalibration of the zero-velocity detection threshold is an essential prerequisite for zero-velocity-aided inertial navigation. However, the literature is lacking a self-contained calibration method, suitable for large-scale use in unprepared environments without map information or pre-deployed infrastructure. In this paper, the calibration of the zero-velocity detection threshold is formulated as a maximum likelihood problem. The likelihood function is approximated using estimation quantities readily available from the FootSLAM algorithm. Thus, we obtain a method for adaptive thresholding that does not require map information, measurements from supplementary sensors, or user input. Experimental evaluations are conducted using data with different gait speeds, sensor placements, and walking trajectories. The proposed calibration method is shown to outperform fixed-threshold zero-velocity detectors and a benchmark using a speed-based threshold classifier.National Institute of Standards and Technology (NIST
Three levels of metric for evaluating wayfinding
Three levels of virtual environment (VE) metric are proposed, based on: (1) usersâ task performance (time taken, distance traveled and number of errors made), (2) physical behavior (locomotion, looking around, and time and error classification), and (3) decision making (i.e., cognitive) rationale (think aloud, interview and questionnaire). Examples of the use of these metrics are drawn from a detailed review of research into VE wayfinding. A case study from research into the fidelity that is required for efficient VE wayfinding is presented, showing the unsuitability in some circumstances of common metrics of task performance such as time and distance, and the benefits to be gained by making fine-grained analyses of usersâ behavior. Taken as a whole, the article highlights the range of techniques that have been successfully used to evaluate wayfinding and explains in detail how some of these techniques may be applied
Legal Challenges and Market Rewards to the Use and Acceptance of Remote Sensing and Digital Information as Evidence
Bakgrund I den nutida forskningen Ă€r det essentiellt att företag tar hĂ€nsyn till medarbetarnas motivation sĂ„ att de gynnas av det arbetssĂ€tt som tillĂ€mpas. En arbetsmetod som blivit allt vanligare Ă€r konceptet Lean som ursprungligen kommer frĂ„n den japanska bilindustrin. Lean har idag utvecklats till ett allmĂ€ngiltigt koncept som tillĂ€mpas i flertalet branscher vĂ€rlden över. Trots att konceptet innebĂ€r flertalet positiva aspekter har det fĂ„tt utstĂ„ stark kritik nĂ€r det kommer till de mĂ€nskliga aspekterna och forskare har stĂ€llt sig frĂ„gan om Lean Ă€r "Mean". Kritiken hĂ€rleds frĂ€mst till medarbetares arbetsmiljö i form av stress och brist pĂ„ variation, sjĂ€lvbestĂ€mmande, hĂ€lsa och vĂ€lmĂ„ende. FĂ„ empiriska studier har dĂ€remot genomförts som undersöker konsekvenserna som Lean fĂ„r pĂ„ medarbetares upplevda motivation. Syfte VĂ„rt syfte Ă€r att undersöka och öka förstĂ„elsen för medarbetares upplevelser av motivationen i företag som tillĂ€mpar Lean. Vidare har studien för avsikt att utreda om det föreligger en paradox mellan Lean och vad som motiverar medarbetare pĂ„ en arbetsplats. Metod Studien har utgĂ„tt frĂ„n en kvalitativ metod via intervjuer. För att göra en djupare undersökning och analysera hur vĂ„rt fenomen, motivation, upplevs i en kontext med Lean tillĂ€mpade vi SmĂ„-N-studier. Vi har Ă€ven haft en iterativ forskningsansats som förenat den deduktiva och induktiva ansatsen dĂ€r studien pendlat mellan teorier och empiriska observationer fram tills det slutgiltiga resultatet. Slutsatser Utefter medarbetarnas upplevelser har vi identifierat att det inte föreligger nĂ„gon paradox mellan Lean och motivation eftersom övervĂ€gande antal medarbetare upplevde att de Ă€r motiverade Ă€ven om företaget tillĂ€mpar Lean. Dock har studien kunnat urskilja bĂ„de stödjande och motverkande faktorer nĂ€r det kommer till medarbetarnas upplevda arbetsförhĂ„llanden som i sin tur inverkar pĂ„ motivationen. De motverkande faktorerna menar vi frĂ€mst beror pĂ„ att arbetsförhĂ„llandena i somliga fall innehĂ„ller höga prestationskrav, mĂ„lstyrning samt standardiseringar. Vidare upplevs motivationen överlag som mer positiv nĂ€r företagen anvĂ€nder en mjukare form av Lean dĂ€r samtliga medlemmars intressen beaktas.Background In modern research, it is essential that companies consider employeesâ motivation so that they benefit from the applied practices. A working method that has become increasingly common is the concept Lean, which has its origin in the Japanese automotive industry. Today, Lean has evolved into a universal concept that is applied in many industries worldwide. Although the concept involves numerous positive aspects it has endured strong criticism when it comes to the human aspects and researchers have raised the question if Lean is "Mean". Criticism is derived primarily to employeesâ working conditions in terms of stress and lack, variation, autonomy, health and wellbeing. However, few empirical studies have been carried out that examines the impact that Lean has on employeesâ experienced motivation. Aim The aim is to increase the understanding of employeesâ experienced motivation in companies that practice Lean. Further on the study has the intention to investigate if there is a paradox between Lean and what motivates employees on work. Methodology The study has been conducted through a qualitative method by interviews and to be able to do a deeper examination and analyze how our phenomenon, motivation, is experienced in a Lean context we applied small-N-studies. Our strategy has been iterative, combining both a deductive and inductive approach, where the study has varied between theories and empirical observations until the final result. Conclusions We have identified that there is no paradox between Lean and motivation since the majority of employeesâ experienced that they are motivated even though the company practice Lean. Nevertheless the study shows that there are both supportive and counteractive factors when it comes to the employeesâ experienced working conditions. The counteractive factors consists foremost of high performance standards, goal steering and standardizations, and have in some cases a negative influence on the working conditions. Furthermore the experienced motivation is more positive overall when the companies use a softer form of Lean where all the membersâ interests are taken into account
Zero-Velocity Detection - A Bayesian Approach to Adaptive Thresholding
A Bayesian zero-velocity detector for foot-mounted inertial navigation
systems is presented. The detector extends existing zero-velocity detectors
based on the likelihood-ratio test, and allows, possibly time-dependent, prior
information about the two hypotheses - the sensors being stationary or in
motion - to be incorporated into the test. It is also possible to incorporate
information about the cost of a missed detection or a false alarm.
Specifically, we consider an hypothesis prior based on the velocity estimates
provided by the navigation system and an exponential model for how the cost of
a missed detection increases with the time since the last zero-velocity update.
Thereby, we obtain a detection threshold that adapts to the motion
characteristics of the user. Thus, the proposed detection framework efficiently
solves one of the key challenges in current zero-velocity-aided inertial
navigation systems: the tuning of the zero-velocity detection threshold. A
performance evaluation on data with normal and fast gait demonstrates that the
proposed detection framework outperforms any detector that chooses two separate
fixed thresholds for the two gait speeds
How much does a man cost? A dirty, dull, and dangerous application
Thesis (M.A.) University of Alaska Fairbanks, 2017This study illuminates the many abilities of Unmanned Aerial Vehicles (UAVs). One area of importance includes the UAV's capability to assist in the development, implementation, and execution of crisis management. This research focuses on UAV uses in pre and post crisis planning and accomplishments. The accompaniment of unmanned vehicles with base teams can make crisis management plans more reliable for the general public and teams faced with tasks such as search and rescue and firefighting. In the fight for mass acceptance of UAV integration, knowledge and attitude inventories were collected and analyzed. Methodology includes mixed method research collected by interviews and questionnaires available to experts and ground teams in the UAV fields, mining industry, firefighting and police force career field, and general city planning crisis management members. This information was compiled to assist professionals in creation of general guidelines and recommendations for how to utilize UAVs in crisis management planning and implementation as well as integration of UAVs into the educational system. The results from this study show the benefits and disadvantages of strategically giving UAVs a role in the construction and implementation of crisis management plans and other areas of interest. The results also show that the general public is lacking information and education on the abilities of UAVs. This education gap shows a correlation with negative attitudes towards UAVs. Educational programs to teach the public benefits of UAV integration should be implemented
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