@article {25, title = {LocateMe: Magnetic-fields-based Indoor Localization Using Smartphones}, journal = {ACM Trans. Intell. Syst. Technol.}, volume = {4}, year = {2013}, pages = {73:1{\textendash}73:27}, abstract = {

Fine-grained localization is extremely important to accurately locate a user indoors. Although innovative solutions have already been proposed, there is no solution that is universally accepted, easily implemented, user centric, and, most importantly, works in the absence of GSM coverage or WiFi availability. The advent of sensor rich smartphones has paved a way to develop a solution that can cater to these requirements.

By employing a smartphone{\textquoteright}s built-in magnetic field sensor, magnetic signatures were collected inside buildings. These signatures displayed a uniqueness in their patterns due to the presence of different kinds of pillars, doors, elevators, etc., that consist of ferromagnetic materials like steel or iron. We theoretically analyze the cause of this uniqueness and then present an indoor localization solution by classifying signatures based on their patterns. However, to account for user walking speed variations so as to provide an application usable to a variety of users, we follow a dynamic time-warping-based approach that is known to work on similar signals irrespective of their variations in the time axis.

Our approach resulted in localization distances of approximately 2m--6m with accuracies between 80--100\% implying that it is sufficient to walk short distances across hallways to be located by the smartphone. The implementation of the application on different smartphones yielded response times of less than five secs, thereby validating the feasibility of our approach and making it a viable solution.

}, keywords = {Indoor localization, Magnetic fields, smartphones, ubiquitous}, issn = {2157-6904}, doi = {10.1145/2508037.2508054}, url = {http://doi.acm.org/10.1145/2508037.2508054}, author = {Subbu, Kalyan and Gozick, Brandon and Ram Dantu} } @article {8, title = {Safe Driving Using Mobile Phones}, journal = {Trans. Intell. Transport. Sys.}, year = {2012}, abstract = {

As vehicle manufacturers continue to increase their emphasis on safety with advanced driver-assistance systems (ADASs), we propose a device that is not only already in abundance but portable enough as well to be one of the most effective multipurpose devices that are able to analyze and advise on safety conditions. Mobile smartphones today are equipped with numerous sensors that can help to aid in safety enhancements for drivers on the road. In this paper, we use the three-axis accelerometer of an Android-based smartphone to record and analyze various driver behaviors and external road conditions that could potentially be hazardous to the health of the driver, the neighboring public, and the automobile. Effective use of these data can educate a potentially dangerous driver on how to safely and efficiently operate a vehicle. With real-time analysis and auditory alerts of these factors, we can increase a driver{\textquoteright}s overall awareness to maximize safety.

}, keywords = {Accelerometer, mobile phone, road conditions, sensors, vehicle safety}, doi = {10.1109/TITS.2012.2187640}, url = {http://dx.doi.org/10.1109/TITS.2012.2187640}, author = {Fazeen, Mohamed and Gozick, Brandon and Ram Dantu and Bhukhiya, Moiz and Gonz{\'a}lez, Marta C.} } @conference {36, title = {Indoor localization through dynamic time warping}, booktitle = {2011 IEEE International Conference on Systems, Man, and Cybernetics}, year = {2011}, month = {10/2011}, address = {Anchorage, AK}, abstract = {

Identifying and locating oneself in different hallways of high rise buildings forms the classic indoor localization problem. GPS does not work indoors and WiFi may not be omnipresent. This paper presents a novel approach to ambient magnetic fields based indoor localization. We present a system that classifies magnetic signatures using dynamic time warping. Specifically, by aligning similar magnetic signatures that differ in magnitude or time, we classify the signatures and infer the location irrepective of the person and his/her mode of commuting. A Nexus One smartphone was employed, utilizing its builtin magnetic field sensor to create a user friendly localization application solely on the phone. By using a variety of subjects including sighted, blindfolded and people using wheelchairs to handle the human speed variation problem, we evaluated the system across 26 and 15 hallways of two different buildings and obtained accuracies of 92.6\%, and 91.1\% respectively. With these encouraging results, we believe our proposed solution is user independent and caters to a wide range of hallways.

}, keywords = {Accuracy, Buildings, Databases, Human, Humans, Legged locomotion, Localization, Magnetometers, mobile phones, sensors, Wheelchairs}, doi = {10.1109/ICSMC.2011.6083906}, author = {Subbu, Kalyan and Gozick, Brandon and Ram Dantu} } @article {9, title = {Magnetic Maps for Indoor Navigation}, journal = {IEEE Transactions on Instrumentation and Measurement}, volume = {60}, year = {2011}, pages = {3883 - 3891}, abstract = {

Magnetic field fluctuations and anomalies inside buildings tend to have a great effect on the compass, which is one of the simplest navigation devices. Alternative navigation requires landmark identification, so those landmarks can be used as guideposts in assisting individuals. By employing a mobile phone with built\_in magnetometer, an extensive data set of 2000 measurements was collected. Using these fields, we identify landmarks and guideposts and create magnetic maps for multiple corridors of a floor in a building. Different phones are used at different sensitivity rates, which effectively portray similar results. Magnetic signatures are used for identifying locations and rooms and are independent of the person, the phone, and the sensitivity of the sensor being used. Magnetic field behavior is demonstrated and compared with theoretical distributions of these fields. The developed magnetic maps can complement existing visual maps for location tracking and navigation of autonomous robots indoors. These maps are particularly useful during limited visual feedback in poor lighting conditions. Moreover, building designers could include this landmark and guidepost information when developing the architecture of a building, which could in turn help people or robots navigate during disasters and emergency evacuations.

}, keywords = {Buildings, Magnetic field measurement, Magnetic field measurements, Magnetic fields, Magnetometers, Mobile handsets, mobile phones, Navigation, sensors, Uncertainty}, doi = {10.1109/TIM.2011.2147690}, author = {Gozick, Brandon and Subbu, Kalyan and Ram Dantu and Maeshiro, Tomyo} }