Browsing by Subject "Navigation"
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Item Open Access The aid of colour on spatial navigation: A study in a virtual hospital environment(ACM, 2016) Kumaoğlu, Özge; Olguntürk, NilgünThe aim of this study is to explore the effects of colour as visuo-spatial cue on spatial navigation and developing a cognitive map in elderly in a simulated virtual hospital environment. The study further purports to explore whether it is possible to improve elders' spatial navigation and cognitive mapping performances as well as younger-aged group, by the aid of coloured visuo-spatial cues. © 2016 ACM.Item Open Access Autonomous navigation of robotic units in mobile sensor network(2012) Nazlibilek, S.This work is motivated by the problem of detecting buried anti-tank and anti-personnel mines in roads or some border regions. The problem is tried to be solved by use of small mobile robotic sensors and their some abilities such as measurement of local fields, navigation around a region, communications with each other, and constituting team within a mission area. The aim of this work is to investigate the navigation problem for the team behavior of mobile sensors within a potential field available in a small-scale environment such as an indoor area or an outdoor region. The mobile sensor network here is a collection of robotic units with sensing capability of earth magnetic field anomalies. A new kind of positioning system is needed for their collective behavior. In this work, a new method of navigation is proposed as a local positioning system. It utilizes ultrasound and radio frequency information to determine the coordinates of the points inside the operational area. The method proposed here is compared with the ultra wideband ranging ping-pong method that is used widely in recent applications. A time division multiple access method is used for the communications among the mobile sensors. The results on the positioning methods together with several simulations and experimental works are given. It is shown that the positioning method utilizing ultrasound-radio frequency method can give fairly good results. © 2012 Elsevier Ltd. All rights reserved.Item Open Access Comparative analysis of different approaches to target differentiation and localization with sonar(Elsevier, 2003) Barshan, B.; Ayrulu, B.This study compares the performances of different methods for the differentiation and localization of commonly encountered features in indoor environments. Differentiation of such features is of interest for intelligent systems in a variety of applications such as system control based on acoustic signal detection and identification, map building, navigation, obstacle avoidance, and target tracking. Different representations of amplitude and time-of-2ight measurement patterns experimentally acquired from a real sonar system are processed. The approaches compared in this study include the target differentiation algorithm, Dempster-Shafer evidential reasoning, different kinds of voting schemes, statistical pattern recognition techniques (k-nearest neighbor classifier, kernel estimator, parameterized density estimator, linear discriminant analysis, and fuzzy c-means clustering algorithm), and artificial neural networks. The neural networks are trained with different input signal representations obtained usingpre-processing techniques such as discrete ordinary and fractional Fourier, Hartley and wavelet transforms, and Kohonen's self-organizing feature map. The use of neural networks trained with the back-propagation algorithm, usually with fractional Fourier transform or wavelet pre-processing results in near perfect differentiation, around 85% correct range estimation and around 95% correct azimuth estimation, which would be satisfactory in a wide range of applications. © 2002 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.Item Open Access Computer vision based forest fire detection(IEEE, 2008) Töreyin, B. Uğur; Çetin, A. EnisLookout posts are commonly installed in the forests all around Turkey and the world. Most of these posts have electricity. Surveillance cameras can be placed on to these surveillance towers to detect possible forest fires. Currently, average fire detection time is 5 minutes in manned lookout towers. The aim ofthe proposed computer vision based method is to reduce the average fire detection rate. The detection method is based on the wavelet based analysis of the background images at various update rates.Item Open Access Exploiting navigational queries for result presentation and caching in Web search engines(John Wiley & Sons, Inc., 2011) Ozcan, R.; Altingovde, I. S.; Ulusoy, O.Caching of query results is an important mechanism for efficiency and scalability of web search engines. Query results are cached and presented in terms of pages, which typically include 10 results each. In navigational queries, users seek a particular website, which would be typically listed at the top ranks (maybe, first or second) by the search engine, if found. For this type of query, caching and presenting results in the 10-per-page manner may waste cache space and network bandwidth. In this article, we propose nonuniform result page models with varying numbers of results for navigational queries. The experimental results show that our approach reduces the cache miss count by up to 9.17% (because of better utilization of cache space). Furthermore, bandwidth usage, which is measured in terms of number of snippets sent, is also reduced by 71% for navigational queries. This means a considerable reduction in the number of transmitted network packets, i.e., a crucial gain especially for mobile-search scenarios. A user study reveals that users easily adapt to the proposed result page model and that the efficiency gains observed in the experiments can be carried over to real-life situations. © 2011 ASIS&T.Item Open Access Identification of target primitives with multiple decision-making sonars using evidential reasoning(Sage Publications Ltd., 1998-06) Ayrulu, B.; Barshan, B.In this study, physical models are used to model reflections from target primitives commonly encountered in a mobile robot's environment. These targets are differentiated by employing a multitransducer pulse/echo system that relies on both time-of-flight data and amplitude in the feature-fusion process, allowing more robust differentiation. Target features are generated as being evidentially tied to degrees of belief, which are subsequently fused by employing multiple logical sonars at geographically distinct sites. Feature data from multiple logical sensors are fused with Dempster's rule of combination to improve the performance of classification by reducing perception uncertainty. Using three sensing nodes, improvement in differentiation is between 10% and 35% without false decision, at the cost of additional computation. The method is verified by experiments with a real sonar system. The evidential approach employed here helps to overcome the vulnerability of the echo amplitude to noise, and enables the modeling of nonparametric uncertainty in real time.Item Open Access Kinect based intelligent wheelchair navigation with potential fields(IEEE, 2014) Özçelikörs, M.; Çoşkun, A.; Say, M. Girayhan; Yazici, A.; Yayan, U.; Akçakoca, M.Increasing elderly people population and people with disabilities constitute a huge demand for wheelchairs. Wheelchairs have an important role on improving the lives and mobilization of people with disabilities. Moreover, autonomous wheelchairs constitute a suitable research platform for academic and industrial researchers. In this study, Finite state machine (FSM) based high-level controller and Kinect based navigation algorithm have been developed for ATEKS (Intelligent Wheelchair) which has high-tech control mechanisms, low-cost sensors and open source software (ROS, GAZEBO, ANDROID). © 2014 IEEE.Item Open Access Pedestrian dead reckoning employing simultaneous activity recognition cues(Institute of Physics Publishing, 2012-01-11) Altun, K.; Barshan, B.We consider the human localization problem using body-worn inertial/magnetic sensor units. Inertial sensors are characterized by a drift error caused by the integration of their rate output to obtain position information. Because of this drift, the position and orientation data obtained from inertial sensors are reliable over only short periods of time. Therefore, position updates from externally referenced sensors are essential. However, if the map of the environment is known, the activity context of the user can provide information about his position. In particular, the switches in the activity context correspond to discrete locations on the map. By performing localization simultaneously with activity recognition, we detect the activity context switches and use the corresponding position information as position updates in a localization filter. The localization filter also involves a smoother that combines the two estimates obtained by running the zero-velocity update algorithm both forward and backward in time. We performed experiments with eight subjects in indoor and outdoor environments involving walking, turning and standing activities. Using a spatial error criterion, we show that the position errors can be decreased by about 85% on the average. We also present the results of two 3D experiments performed in realistic indoor environments and demonstrate that it is possible to achieve over 90% error reduction in position by performing localization simultaneously with activity recognition.Item Open Access Personal navigation via high-resolution gait-corrected inertial measurement units(IEEE, 2010) Bebek O.; Suster, M.A.; Rajgopal, S.; Fu, M.J.; Huang X.; Çavuşoğlu, M. Cenk; Young, D.J.; Mehregany, M.; Van Den Bogert, A.J.; Mastrangelo, C.H.In this paper, a personal micronavigation system that uses high-resolution gait-corrected inertial measurement units is presented. The goal of this paper is to develop a navigation system that uses secondary inertial variables, such as velocity, to enable long-term precise navigation in the absence of Global Positioning System (GPS) and beacon signals. In this scheme, measured zero-velocity duration from the ground reaction sensors is used to reset the accumulated integration errors from accelerometers and gyroscopes in position calculation. With the described system, an average position error of 4 m is achieved at the end of half-hour walks. © 2010 IEEE.Item Open Access Remediating the data : a study on the interactive dimensions in new media(2005) Şenova, FundaThis thesis analyses the role of interface in altering perception and customizing interaction in new media. It comprehends the correlation of theory and practice while probing into the current debate by means of examples and case studies. The general structure of this research is based on the objectives of interactivity in cultural and social levels. In each level, interactivity is analyzed through function, operation oriented and design-wise aspects of new media. This study focuses on the interactive dimensions in new media and their affects on the user’s perception and engagement within a digitally framed work.Item Open Access The state of the art in mobile graphics research(Institute of Electrical and Electronics Engineers, 2008) Capin, T.; Pulli, K.; Akenine-Möller, T.High-quality computer graphics let mobile-device users access more compelling content. Still, the devices' limitations and requirements differ substantially from those of a PC. This survey of mobile graphics research describes current solutions in terms of specialized hardware (including 3D displays), rendering and transmission, visualization, and user interfaces. © 2008 IEEE.Item Open Access Utilization of navigational queries for result presentation and caching in search engines(ACM, 2008-10) Özcan, Rıfat; Altıngövde, İsmail Şengör; Ulusoy, ÖzgürWe propose result page models with varying granularities for navigational queries and show that this approach provides a better utilization of cache space and reduces bandwidth requirements.