Towards Building iBeacon-basedSmart Indoor Environments forVisually Impaired Users

Jashmi LagisettyArizona State UniversityIra A. Fulton Schools ofEngineering, AZ 85281, USAjlagiset@asu.edu

Devi Archana PaladuguArizona State UniversityIra A. Fulton Schools ofEngineering, AZ 85281, USAapaladug@asu.edu

Dr. Baoxin LiArizona State UniversityIra A. Fulton Schools ofEngineering, AZ 85281, USAbaoxin.li@asu.edu

HCIxB 2017, May 6-11, 2017 , Denver, Colorado , USA.

AbstractA smart environment may help a new person quickly getacquainted about the environment. Such features can bemore critical for cases of making an indoor environmentmore accessible to people with visual impairment. Withthe intention to promote the integration of visually impairedpeople in society, this paper reports efforts on methodolo-gies for building smart and accessible indoor office envi-ronments with the help of Apple’s Bluetooth Low Energy(BLE) technology called iBeacon to provide location aware-ness and enable easy access to information about the en-vironment to people with visual impairment. We presentour preliminary work on developing an iterative based ap-proach in improving the configuration of given number ofiBeacons to gain optimal signal coverage in a given officespace environment and enabling smart features such astagging points of interest and push notifications.

Author KeywordsBluetooth Technology, iBeacon, Indoor Localization, Prox-imity, Bluetooth Low Energy

ACM Classification KeywordsH.5.2 [User Interfaces]: Methodology

IntroductionImproving accessibility to public buildings by people withspecial needs has been an important societal commitmentthat is mandated by federal laws [1]. In the information age,accessibility can mean more than simply providing physicalaccommodations like ramps for wheel-chairs. For example,a building can be truly accessible to people with visual im-pairment if localization within the building is provided to auser somehow. Better yet, accessibility will be fundamen-tally improved, if a user can be made aware of importantlocation-specific information like functions of offices nearthe user within a building. Such a broadened sense of ac-cessibility is critically related to indoor localization.

GPS-based devices, in general, do not provide high-precisionlocalization in an indoor setting, and thus researchers aretrying to discover alternate ways to gather accurate location-based information for indoor environments. Significantamount of work is being done in the field of indoor navi-gation and positioning using Apple’s BLE technology baseddevice called iBeacon [2].

There have been previous works to help users in the as-pect of navigation by using a small volume based deviceswhich are of low cost and have easy integration with blue-tooth technology based mobile devices [6] [15]. One of thenotable bluetooth based technology is Apple’s implemen-tation of BLE technology called iBeacon. Work has beendone to help navigate patients to their ward [14] or give aninteractive historical experience to visitors of a museum [8].Although localization and navigation of people with visualimpairments are described in [7] [5] [12], these works donot consider in providing high localization accuracy tailor-made to a specific environment. The novelty of the pro-posed approach therefore lies in the fact that it addressesthe question on how to practically prepare the environment

for maximum signal coverage and how it can be expandedto more complex requirements such as access and gaininformation about a given indoor environment to visuallyimpaired users.

We work with iBeacon technology by using small cost-effective coin sized devices called Estimote Beacons(iBeacon).This may be used to estimate the proximity of another bluetooth-enabled device. With multiple iBeacons deployed in an en-vironment, we may able to achieve localization of a usercarrying a bluetooth-enabled device.

For a given environment, with the above technology, wemay be able to make an environment more accessible byproviding a user with localization information. Further, ad-ditional location-specific information can be provided to auser. This idea has been proposed to make, for example, amarket smarter so that functions like pushing relevant ad-vertisements may be supported when a user walks by anaisle [10]. In practice, if a finite number of iBeacons needto be deployed for an environment, there may be optimalpositioning of the iBeacons (for achieving best localization)that cannot be purely determined by the geometry of theenvironment, since there are other factors like interferenceof walls or other radio wave-emitting devices.

In this paper, we develop an approach for iteratively discov-ering such an optimal configuration of a given number ofiBeacons for more accurate localization. The main objectiveof the proposed system is to enhance smart functions likepushing notifications, tagging a point of interest, providinglocation-specific information to everyone, especially userswith visual impairment.

As iPhones are popular among visually impaired people[11] and eliminate the cost of acquisition and learning touse a new device, we design an iOS-based app to assist a

user in positioning the iBeacons for making an environmentaccessible.

Figure 1: Floor Plan of OfficeSpace

Such a technology would be very useful for making the en-vironment most accessible to people with visual impair-ment as they can familiarize with the environment withoutdepending on anybody. The current stage our focus is onalgorithmic aspects of the proposed framework and theexperiments have been focused on testing the easinessof use of the app and effectiveness of the methodology inhelping the configuration of the iBeacons and providing aninteractive based experience of getting to know informationabout the environment.

Supporting iBeacon ConfigurationEffect of Received Signal Strength(RSSI): The informa-tion obtained from a smart environment depends on thecoverage of the signal across the office space. iBeaconsuse BLE technology which works on the principle of Re-ceived Signal Strength (RSSI). In an ideal obstacle-freeenvironment, the signal strength of the bluetooth devicesremains constant and strong. The distance of the object’sestimated position from its real position is termed as lo-cation accuracy. Several localization techniques such astrilateration, multilateration, proximity technique and otherlocalizations algorithms [9] [13] are used to give an esti-mate of the position of interest. These methods work onthe concept of estimating distinct location coordinates ofthe object by knowing the position coordinates of the signalemitting sources and the distances of the object from thesesources.

Figure 2: Tagging of a place ofinterest

Ideal and Real world: In an ideal/theoretical scenario, wecan estimate distinct location coordinates of the objectby knowing the position coordinates of the signal emittingsources and the distances of the object from these sources

using the above mentioned methods. Although the range ofan iBeacon is 70 m, its full effect can we witnessed in theproximity of 4m. This is due to the real world environmen-tal factors such as carpeted floors, cubicles, printers andWiFi routers, metallic cabinets, wooden furniture, cables,servers, computers, mirrors, glass walls and people movingwithin the location space highly influence the signal prop-agation. This hampers the estimation of obtaining locationcoordinates and location accuracy. In order to get a bet-ter understanding of the relative distance between differentiBeacons, iBeacon technology defines four proximity zonesfor estimating distance to a iBeacon: immediate (very closeto the iBeacon), near (about 1-3 m from the iBeacon), far(further away or the signal is fluctuating too much to makea better estimate), unknown (proximity cannot be deter-mined) [4].

Generating Heat maps: This sub section describes thecore of our methodology. We obtain user generated locationpoints and their corresponding proximity zones (explainedin detail in “Testing the Environment" section). A mesh-based heat map is charted based on location accuracy bythe data points obtained. Each colour palette denotes therange of location accuracy recorded at that instance of thegrid. Ideal heat map is charted purely on distance betweenthe signal source and user location coordinates. Heat mapgenerated from the user movement(practical heat map) iscompared to the ideal heat map. Location accuracies at ev-ery point are compared. Ideally, the practical map and theideal map should be similar unless there is a presence ofsignificant signal distorting agents. A distortion is said tooccur if there is a decrease in reported location accuracy inthe practical heat map. Areas where the practical heat mapperforms worse, i.e., shows a lower range on the accuracyscale, denote possibility of distortion in the environment. Allsuch distortions are identified.

Iterative based iBeacon Movement Suggestion:

Figure 3: Launch Page

Figure 4: Iteration 1

The idea is to reduce areas showing distortions and sug-gest iBeacon placement where information passage ismaximized. This is achieved by arranging iBeacons to giveexcellent/good location accuracy zones. The parametersfor iBeacon movement depend on its proximity to the clos-est iBeacon, number, extent and priority of each distortion.Hence, a look-up table is generated based on this derivedinformation. Also, signal coverage at original position ofiBeacon and the suggestive new position is constantly com-pared to make sure the original iBeacon signal is not beingjeopardized due to the new suggestion. An optimum posi-tion is suggested so a significant amount of original area isstill under coverage and a good amount of distorted regionis bought under coverage. This process is done 2-3 timesto get an accessible location map which emulates the idealheat map or has maximum amount of excellent/good accu-racy zones.

Enabling Smart FeaturesFeatures to facilities the flow on easy access to informationand spreading location awareness are vital for designing asmart environment. These smart features can be useful formaking an indoor environment more accessible to peoplewith visual impairment.

1. Tagging: The point of interest can be tagged by giv-ing the coordinates and name of the tagged point.A example of such feature is as shown in Figure 2.Whenever a tagged point of interest appears whilewalk through the indoor space, information about thelocation can be provided to the user.

2. Push Notification: Irrespective of the app runningin foreground or background, a push notification can

be released to give information about the locationthe user is at. This experience facilitates a sense offamiliarity and location awareness.

Testing the EnvironmentInstallation of iBeacons : This section covers how theenvironment is set up to make it smart and accessible bythe visually impaired people. The setting up and installationof the iBeacons has to be done by people with normal vi-sion. We conduct experiments in a small 6mx8m section ofa large office space unit office as shown in Figure 1. EachLocation Proximity iBeacon is set to maximum Broadcast-ing Power (+4 dBm) and affixed one per wall at the centreof each wall of a rectangular shaped office space. The useris asked to hold the bluetooth-enabled mobile at chest-leveland walk around the location. The user is at liberty to walkanywhere inside the space based on the arrangement offurniture or cubicle walls or any other physical obstruction.Since finding the best configuration for iBeacon position-ing technique is an iterative process, we use a swift-basediOS app equipped with Estimote Indoor Location SDK [3] tomap user position in the considered office space. This SDKassigns an origin to the bottom left corner of the 6mx8mgrid. Due to human traffic and other external environmen-tal factors, the readings vary slightly every time the testingis performed. We performed the experiment over 50 timesand used our lab mates as test subjects.

Interface : As shown in Figure 3, “Start” option on the in-terface provides the estimated location coordinates and es-timated location accuracy at every step the user takes. Thelocation accuracy is the value that estimates the proximityzone of the iBeacon. This value tends to fluctuate based onthe obstacles in the environment. The location coordinatesand accuracy are recorded at every point. Every user traceresults in an iteration. “Plot” option envisions and displays

detailed heat maps showing the effect and extent of locationaccuracy in ideal and practical scenarios.

Figure 5: Iteration 2

Figure 6: Iteration 3

Iterative Suggestions : Figures 4, 5, 6 show the threeiterations: 1,2,3. We can see that the ideal and practicalheat maps for every iteration are compared based on levelof accuracy as indicated by definitive colour coded levels,i.e, excellent, good, medium and poor. At every iteration,the suggestion of the new iBeacon estimated position isgiven in the form of new coordinates and the direction fromits original placement. Iteration 1 Figure 4 shows there is apossible distortion in the top left corner, hence the method-ology suggests the direction of movement and new iBea-con placement coordinates of the closest iBeacon to bringthe given environment into optimal signal coverage. Thissuggestion is displayed at the bottom of the screen. Theoptimal signal coverage is a trade off between maximizinglocation accuracy and minimizing the distorted regions with-out jeopardizing the existing signal coverage area.

Based on the new coordinates of the iBeacon sugges-tion from the previous step, the position of iBeacons areupdated. The entire process of indoor movement is re-peated again as shown in Iterations 2 and 3 Figure 5, Fig-ure 6. There could be unseen parameters that would havechanged after the first iteration. Hence, we go for anotheriteration with the new iBeacon positions. The motive is toiteratively find the optimal iBeacon placement which is theresult of the suggestion derived by comparing re-calculatedideal heat map with the latest user movement based (practi-cal) heat map. The method tries to achieve this in 2-3 itera-tions and finalize the best of 3 iterations.

Interface for Visually Impaired User : When deployed, thevisually impaired user has an interface consists of only onescreen, Figure 3. Without any external help, he/she canreceive maximum information about the office room. This

can include position of the user in the given map, importanttagged points such as coffee table, printer, exit door, cubi-cle number, direction of movement, orientation on the userin the map. Another feature of the iBeacon set up is thatthe user can get notifications about any tagged point, forinstance, if the visually impaired user passes by the confer-ence room, the iBeacon based app lets him/her know aboutthe event currently happening in the hall. The app has con-trasting colours, big clear lettering and is easy-to-use. Theinterface is pretty intuitive and requires minimum effort touse it.

Across BordersLooking at visual impairment beyond the level of disabilitycan be looked at as an opportunity to bring about a changeof style of living. This gives us an opportunity to help visu-ally impaired people lead an independent life where theirsocial challenged are not limited. Designing assistive tech-nology to help them do basic activities like getting familiar-ized about an office environment without the need for ask-ing for assistance is what this paper wants to achieve. Thebeauty of making an environment easy accessible is that ithelps people from all walks of life. In order to improve thequality of life for visual impaired people, in this work we fo-cused on iBeacon technology to make an office room moreaccessible and help visually impaired people gain maximuminformation about the environment. The next step in ourwork is to conduct surveys by asking different age basedvisually impaired participants and see how they would re-spond to the smart environment and collect feedback to im-prove the experience. We want to improve the scalability ofthe map considered by expanding to a larger office space,the experience can be enhanced using voice-activated fea-tures to give such visually impaired users a walk-throughinteractive experience by enabling access to the local envi-ronment.

AcknowledgmentThe work was supported in part by National Science Foun-dation. Any views expressed in this work are solely of theauthors and do not necessarily reflect that of NSF.

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