Asynchronous Ultrasonic Trilateration for Indoor Positioning of Mobile Phones

Spatial awareness is fast becoming the key feature on today‟s mobile devices. While accurate outdoor navigation has been widely available for some time through Global Positioning Systems (GPS), accurate indoor positioning is still largely an unsolved problem. One major reason for this is that GPS and other Global Navigation Satellite Systems (GNSS) systems offer accuracy of a scale far different to that required for effective indoor navigation. Indoor positioning is also hindered by poor GPS signal quality, a major issue when developing dedicated indoor locationing systems. In addition, many indoor systems use specialized hardware to calculate accurate device position, as readily available wireless protocols have so far not delivered sufficient levels of accuracy. This research aims to investigate how the mobile phone‟s innate ability to produce sound (notably ultrasound) can be utilised to deliver more accurate indoor positioning than current methods. Experimental work covers limitations of mobile phone speakers in regard to generation of high frequencies, propagation patternsof ultrasound and their impact on maximum range, and asynchronous trilateration. This is followed by accuracy and reliability tests of an ultrasound positioning system prototype.This thesis proposes a new method of positioning a mobile phone indoors with accuracy substantially better than other contemporary positioning systems available on off-theshelf mobile devices. Given that smartphones can be programmed to correctly estimate direction, this research outlines a potentially significant advance towards a practical platform for indoor Location Based Services. Also a novel asynchronous trilateration algorithm is proposed that eliminates the need for synchronisation between the mobile device and the positioning infrastructure

Ultrasonic Trilateration Methods for Low-Cost Indoor Positioning

Trilateration is a process where distances to known control points or beacons can be used as inputs to algorithms to calculate an object’s position. Most of the common trilateration methods known are fast and reliable, and based on estimating one or more location-dependent signal parameters like Times-of-arrival (TOA), Angle of Arrival (AOA) or Received Signal Strength (RSS). However, costly hardware is needed for such approaches to run reliably, and are too computationally complex both in speed and memory for low-cost hardware.  The demand for low-cost hardware has greatly increased in recent years mostly due to the rapid emergence of internet of things, that promises to bring connectivity to just about everything. As such, leveraging on cheap hardware is an important step to take to achieve accurate indoor positioning.  Because of convenience in generation and transmission, ultrasound is widely and commonly used electronically for distance measurement. The use of ultrasound with cheap hardware for accurate indoor positioning is discussed in this paper. Three localization methods that are reliable and fast enough for cheap hardware are analyzed with emphasis on the speed and memory demands. Experimental results show that the Maximum Likelihood estimation approach is the most accurate. Keywords: Time of arrival; Trilateration; Ultrasound; Localization; Indoor positioning. DOI: 10.7176/ISDE/10-5-04 Publication date:June 30th 2019

LOCATE-US: Indoor Positioning for Mobile Devices Using Encoded Ultrasonic Signals, Inertial Sensors and Graph- Matching

Indoor positioning remains a challenge and, despite much research and development carried out in the last decade, there is still no standard as with the Global Navigation Satellite Systems (GNSS) outdoors. This paper presents an indoor positioning system called LOCATE-US with adjustable granularity for use with commercial mobile devices, such as smartphones or tablets. LOCATE-US is privacy-oriented and allows every device to compute its own position by fusing ultrasonic, inertial sensor measurements and map information. Ultrasonic Local Positioning Systems (ULPS) based on encoded signals are placed in critical zones that require an accuracy below a few decimeters to correct the accumulated drift errors of the inertial measurements. These systems are well suited to work at room level as walls confine acoustic waves inside. To avoid audible artifacts, the U-LPS emission is set at 41.67 kHz, and an ultrasonic acquisition module with reduced dimensions is attached to the mobile device through the USB port to capture signals. Processing in the mobile device involves an improved Time Differences of Arrival (TDOA) estimation that is fused with the measurements from an external inertial sensor to obtain real-time location and trajectory display at a 10 Hz rate. Graph-matching has also been included, considering available prior knowledge about the navigation scenario. This kind of device is an adequate platform for Location-Based Services (LBS), enabling applications such as augmented reality, guiding applications, or people monitoring and assistance. The system architecture can easily incorporate new sensors in the future, such as UWB, RFiD or others.Universidad de AlcaláJunta de Comunidades de Castilla-La ManchaAgencia Estatal de Investigació

A Meta-Review of Indoor Positioning Systems

An accurate and reliable Indoor Positioning System (IPS) applicable to most indoor scenarios has been sought for many years. The number of technologies, techniques, and approaches in general used in IPS proposals is remarkable. Such diversity, coupled with the lack of strict and verifiable evaluations, leads to difficulties for appreciating the true value of most proposals. This paper provides a meta-review that performed a comprehensive compilation of 62 survey papers in the area of indoor positioning. The paper provides the reader with an introduction to IPS and the different technologies, techniques, and some methods commonly employed. The introduction is supported by consensus found in the selected surveys and referenced using them. Thus, the meta-review allows the reader to inspect the IPS current state at a glance and serve as a guide for the reader to easily find further details on each technology used in IPS. The analyses of the meta-review contributed with insights on the abundance and academic significance of published IPS proposals using the criterion of the number of citations. Moreover, 75 works are identified as relevant works in the research topic from a selection of about 4000 works cited in the analyzed surveys

A two phase framework for visible light-based positioning in an indoor environment: performance, latency, and illumination

Recently with the advancement of solid state lighting and the application thereof to Visible Light Communications (VLC), the concept of Visible Light Positioning (VLP) has been targeted as a very attractive indoor positioning system (IPS) due to its ubiquity, directionality, spatial reuse, and relatively high modulation bandwidth. IPSs, in general, have 4 major components (1) a modulation, (2) a multiple access scheme, (3) a channel measurement, and (4) a positioning algorithm. A number of VLP approaches have been proposed in the literature and primarily focus on a fixed combination of these elements and moreover evaluate the quality of the contribution often by accuracy or precision alone. In this dissertation, we provide a novel two-phase indoor positioning algorithmic framework that is able to increase robustness when subject to insufficient anchor luminaries and also incorporate any combination of the four major IPS components. The first phase provides robust and timely albeit less accurate positioning proximity estimates without requiring more than a single luminary anchor using time division access to On Off Keying (OOK) modulated signals while the second phase provides a more accurate, conventional, positioning estimate approach using a novel geometric constrained triangulation algorithm based on angle of arrival (AoA) measurements. However, this approach is still an application of a specific combination of IPS components. To achieve a broader impact, the framework is employed on a collection of IPS component combinations ranging from (1) pulsed modulations to multicarrier modulations, (2) time, frequency, and code division multiple access, (3) received signal strength (RSS), time of flight (ToF), and AoA, as well as (4) trilateration and triangulation positioning algorithms. Results illustrate full room positioning coverage ranging with median accuracies ranging from 3.09 cm to 12.07 cm at 50% duty cycle illumination levels. The framework further allows for duty cycle variation to include dimming modulations and results range from 3.62 cm to 13.15 cm at 20% duty cycle while 2.06 cm to 8.44 cm at a 78% duty cycle. Testbed results reinforce this frameworks applicability. Lastly, a novel latency constrained optimization algorithm can be overlaid on the two phase framework to decide when to simply use the coarse estimate or when to expend more computational resources on a potentially more accurate fine estimate. The creation of the two phase framework enables robust, illumination, latency sensitive positioning with the ability to be applied within a vast array of system deployment constraints

Sisäpaikannus: Teknologiat ja käyttötapaukset vähittäiskaupan alalla

Indoor positioning systems (IPS) are required in buildings to offer the possibility to position people and assets indoors, as the widely utilized GPS signal cannot penetrate through walls. IPSs are already implemented in many indoor environments. Several indoor positioning technologies exist, but none of them is clearly a dominant technology over the others. Consequently, this study identifies the different kinds of indoor positioning technologies and methods as well as the use cases they are used in. For this purpose, six companies using or developing indoor positioning systems were interviewed. The interviews were held in person, and they were 60-minute long semi-structured interviews with a set of questions in Appendix 1. In addition, two companies interested in indoor positioning, and that are working with retail were interviewed in 30-minute semi-structured interviews with questions in Appendix 2. Indoor positioning is employed in the interviewed companies to help users to navigate in public spaces; raise employee satisfaction in an office; improve customer service and satisfaction in malls, stores, and restaurants and develop processes and safety in warehouses. These different use cases have distinctive specifications and needs for indoor positioning, and thus, there is not a simple solution as to which technology is the right choice for a particular use case. Nevertheless, three points affecting the choice of indoor positioning technology were concluded from the interviews: 1) the accuracy of a technology, 2) whether the positioning happens through a tag or a mobile device, and 3) if positioning infrastructure, such as anchor nodes, can be installed in the building. Finally, based on the interviews, a suggested model for an indoor positioning system for a retail company is presented in a form of a Value Network Configuration.Sisäpaikannusjärjestelmiä tarvitaan rakennuksissa, jotta ihmisiä ja tavaroita voidaan paikantaa sisätiloissa, sillä ulkona yleisesti käytetty GPS signaali ei pysty läpäisemään rakennusten seiniä. Vaikka sisäpaikannusta käytetäänkin jo useissa eri sisätiloissa ja useita eri sisäpaikannusteknologioita on olemassa, mikään niistä ei ole selvästi hallitseva teknologia. Tässä tutkimuksessa tunnistetaan eri sisäpaikannusteknologiat ja –tekniikat kuten myös niitä hyödyntävät käyttötapaukset. Tätä varten haastateltiin kuutta eri yritystä, jotka käyttävät tai tarjoavat sisäpaikannusjärjestelmiä. Haastattelut olivat puolistrukturoituja, kestivät 60 minuuttia ja ne pidettiin kasvotusten. Lisäksi haastateltiin 30 minuutin puolistrukturoiduissa haastatteluissa kahta kaupan alaan liittyvää yritystä, jotka ovat kiinnostuneita sisäpaikannuksesta. Haastattelukysymykset ovat liitteissä 1 ja 2. Sisäpaikannusta käytetään haastatelluissa yrityksissä käyttäjien navigoinnin helpottamiseksi julkisissa tiloissa, työntekijöiden tyytyväisyyden kasvattamiseen toimistossa, asiakaspalvelun ja asiakkaiden tyytyväisyyden parantamiseen ostoskeskuksissa, kaupoissa ja ravintoloissa sekä prosessien ja turvallisuuden kehittämiseen varastoissa. Näillä eri käyttötapauksilla on hyvin erilaiset vaatimukset ja tarpeet sisäpaikannukselle, joten ei ole olemassa vain yhtä hyvää teknologista ratkaisua tietylle käyttötapaukselle. Haastatteluista oli kuitenkin mahdollista muodostaa kolme sisäpaikannusteknologian valintaan vaikuttavaa asiaa: 1) sisäpaikannusteknologian tarkkuus, 2) tapahtuuko paikannus mobiililaitteen vai käyttäjän kantaman tunnisteen kautta ja 3) voiko paikannusjärjestelmän tukiasemia asentaa rakennukseen. Lopuksi esitellään ehdotelma sisäpaikannusmallista arvoverkkokonfiguraatiolla (Value Network Configuration) vähittäiskaupan alan yritykselle haastatteluiden perusteella