University of Tr´
as-os-Montes and Alto Douro
Wearable devices for blind orientation and
navigation
Lu´ıs Miguel Alves Fernandes
Supervisor: Professor Hugo Paredes
Co-supervisor: Professor Jo˜
ao Barroso
Wearable devices for blind orientation and
navigation
By
Lu´ıs Miguel Alves Fernandes
Supervisor: Professor Hugo Paredes
Co-supervisor: Professor Jo˜
ao Barroso
Thesis submitted to
UNIVERSITY OF TR ´AS-OS-MONTES AND ALTO DOURO in partial fulfilment of the requirements
for the degree of MASTER OF SCIENCE
in Software Engineering, accordingly with the provisions of DR – I A–series, n.o 74/2006, March 24th and accordingly with the
Regulation of the Postgraduate Studies of UTAD DR, 2nd series – Deliberation n.o 2391/2007
Supervisors:
Professor Hugo Paredes
Assistant Professor
Engineering Department, Science and Technology School University of Tr´as–os–Montes and Alto Douro
Professor Jo˜ao Barroso
Associate Professor with Habilitation
Engineering Department, Science and Technology School University of Tr´as–os–Montes and Alto Douro
I will treasure the knowledge like a squirrel treasures acorns. Unknown
To my parents, brother, grandparents, uncles and cousins
Wearable devices for blind orientation and navigation
Lu´ıs Miguel Alves FernandesSubmitted to the University of Tr´as–os–Montes and Alto Douro
in partial fulfilment of the requirements for the degree of Master of Science
Abstract – Over time, people in the face of vicissitudes and the concrete necessities of life were forced, in a natural and implicitly way, to create defence, protection and even survival mechanisms, having the need to adapt to the surroundings and to use the offered goods and information.
In the case of blind or partially sighted people, the surrounding environment de per si shows up as a challenge and natural barrier, limiting their action, movement and orientation. Despite the navigation and guidance systems being in constant evolution and development, there are still many gaps and constraints in the support and help of people with visual impairments, and thus, the research done in this specific field deserves all the credit and support at all levels, always having as a beacon the improvement the welfare of people with these difficulties.
The aim of the project on which this dissertation is part of (CE4Blind), is built upon the advantages of the latest technological developments to create innovative solutions that can strongly contribute to the support and inclusion of people with special needs, specifically the blind community and all people suffering from visual impairment.
Perfectly aware that the work presented herein tries to support and contribute to the inclusion of blind and partially sighted people - a problem affecting more and more the world’s population - in terms of their mobility, guidance and navigation, an architecture, that is governed by bases that the literature considers feasible and reliable, is specified, designed and implemented, also taking into account the importance of partnerships with various institutions, and even with the Governments and Countries themselves.
As personal motivation, new ideas and contributions have been brought, always keeping in mind a greater good, which is the quality of life of those in need, in particular, the visually impaired.
Keywords: Software Architectures, Architectural Styles, Blind Navigation, Navi-gation, Guidance, Blind, Visually Impaired.
Dispositivos port´
ateis para orienta¸c˜
ao e navega¸c˜
ao de cegos
Lu´ıs Miguel Alves FernandesSubmetida `a Universidade de Tr´as–os–Montes e Alto Douro
em cumprimento parcial dos requisitos para o grau de Mestre
Resumo – Ao longo do tempo, as pessoas perante as vicissitudes e as necessidades concretas da vida foram obrigadas, de forma natural e impl´ıcita a criar mecanismos de defesa, protec¸c˜ao e at´e de eventual sobrevivˆencia, tendo a necessidade de adaptar-se ao meio envolvente e a retirar dele os bens e informa¸c˜ao necess´arios.
No caso concreto de pessoas cegas ou ambl´ıopes, o ambiente envolvente de per si surge como um desafio e barreira naturais, limitando a sua ac¸c˜ao, locomo¸c˜ao e orienta¸c˜ao. Apesar dos sistemas de navega¸c˜ao e orienta¸c˜ao estarem em constante evolu¸c˜ao e desenvolvimento, ainda se registam muitas lacunas e restri¸c˜oes no apoio e ajuda a pessoas com deficiˆencias visuais, pelo que a investiga¸c˜ao feita na ´area merece todo o m´erito e apoio a todos os n´ıveis tendo sempre como farol a melhoria do bem estar das pessoas com estas dificuldades.
O objectivo do projecto em que a presente disserta¸c˜ao se insere (CE4Blind), pre-tende alavancar-se nas vantagens que as tecnologias emergentes proporcionam, para criar solu¸c˜oes inovadores que poder˜ao contribuir fortemente para suportar e incluir pessoas com necessidades especiais, mais concretamente a comunidade cega e todas as pessoas com dificuldades a n´ıvel da vis˜ao.
Consciente que o trabalho apresentado tenta suportar e contribuir para a inclus˜ao de pessoas cegas e ambl´ıopes - um problema que afecta cada vezes mais a pop-ula¸c˜ao mundial - a n´ıvel da sua locomo¸c˜ao, orienta¸c˜ao e navega¸c˜ao, especifica-se, desenha-se e implementa-se uma arquitectura que se rege por bases que a lit-eratura considera vi´aveis e fi´aveis, tendo sempre em considera¸c˜ao a importˆancia das parcerias com v´arias Institui¸c˜oes, e at´e dos pr´oprios Governos e Pa´ıses.
Por motiva¸c˜ao pessoal, tentaram-se ainda trazer novas ideias e contributos tendo sempre em mente um bem superior, que ´e a qualidade de vida daqueles que neces-sitam, mais concretamente os cegos e ambl´ıopes.
Palavras–chave: Arquitecturas de Software, Estilos Arquitecturais, Navega¸c˜ao para cegos, Navega¸c˜ao, Orienta¸c˜ao, Cegos, Ambl´ıopes.
Acknowledgments
“Fabricando fit faber ” – “Practice makes perfect.”
The incessant search for the best and for knowledge has always been latent in my mind.
When choosing the area of Computer Science, I was convinced that this would def-initely become part of my path.
This path was not easy, but with a permanent motivation of reaching up, step–by– step, with the goal set in my mind.
The research work presented in this dissertation turned out to be a confirmation of my initial will, even with the difficulties that have arisen in the context of the work accomplished.
At this point, I wish to thank all the people who accompanied me from the start -this will - with either support or encouragement and constant teachings.
Firstly, I would like to express my gratitude to my mentors, Professor Hugo Pare-des and Professor Jo˜ao Barroso, for their orientation and, in particular, for the permanent monitoring throughout this project, as well as the tremendous support provided, without which this process wouldn’t have been possible.
At this special time, I could never forget the colleagues and friends of the research
group at UTAD, namely Andr´e Sousa, Diogo Azevedo, Hugo Fernandes and Tˆania Rocha, who always stressed the availability, readiness and sense of support in all circumstances to which I shall be eternally grateful.
During this path already mentioned, I couldn’t also forget of some of the Profes-sors who also marked me on this journey, especially ProfesProfes-sors Ant´onio Gouveia, Benjamin Fonseca, Leonel Morgado, Lu´ıs Filipe Barbosa, Paulo Martins and V´ıtor Filipe.
I also wish at this time to say a word of special thanks to Professor Ramiro Gon¸calves, Director of this mui nobre curso, for the support and optimism always demonstrated. To the great institution - the University of Tras-os-Montes and Alto Douro (UTAD) - and the Department of Engineering of UTAD I would like to express my greatest thanks for welcoming me during these past years and allowing me to accomplish this goal.
I can not pass this stage without thanking, with affection, INESC TEC and the FCT. Thank you very much.
To all my friends, recalling Ricardo Rodrigues Nunes, Gon¸calo Matos, Daniel Pe-drosa, Wallace Ugulino, Wellisom Souza, Jo˜ao Alves, Ricardo Vilela, Tiago Ro-drigues, Guilhermino Morais, R´uben Monteiro, Ana Martins, M´arcia Guerra, Pe-dro Martins, Yasmim Yamaguchi, Alexander and Rolland Klaar, PePe-dro Gon¸calves, Miguel Melo, Telmo Ad˜ao, Filipe Marques and Rui Silva.
Forgive me all those which I may have forgotten to mention, that will always be in my heart.
Finally, to my family who supported me in every circumstance.
To all of you, a big thanks! Lu´ıs Miguel Alves Fernandes
June 2016
UTAD, Vila Real 29th of June, 2016
Agradecimentos
“Fabricando fit faber ” – “ ´E fazendo que se faz (que se aprende)”
A incessante busca pelo melhor e pelo conhecimento esteve sempre latente no meu pensamento.
Ao optar pela ´area de Engenharia Inform´atica, estava convicto de que esse seria o meu caminho.
Esse mesmo caminho n˜ao foi f´acil, mas com motiva¸c˜ao permanente foi-se alcan¸cando, passo-a-passo, o objectivo definido no meu esp´ırito.
O trabalho de investiga¸c˜ao ora apresentado nesta disserta¸c˜ao acabou por se revelar uma confirma¸c˜ao da minha vontade inicial, mesmo com as dificuldades que foram surgindo no ˆambito do trabalho levado a cabo.
Nesta altura, desejo agradecer a todas as pessoas que me acompanharam desde o in´ıcio – desta vontade -, quer com o seu apoio, quer com o est´ımulo e ensinamentos constantes.
Em primeiro lugar exprimo a minha gratid˜ao aos meus orientadores, Professor Doutor Hugo Paredes e Professor Doutor Jo˜ao Barroso, pela orienta¸c˜ao desta dis-serta¸c˜ao, nomeadamente pelo acompanhamento permanente ao longo de todo o tra-balho, bem como pelo enorme apoio prestado, sem os quais este processo n˜ao teria sido poss´ıvel.
N˜ao poderia deixar de lembrar, nesta altura especial, os colegas e amigos do grupo
de investiga¸c˜ao na UTAD, nomeadamente o Andr´e Sousa, o Diogo Azevedo, Hugo Fernandes e Tˆania Rocha, que sempre se salientaram pela disponibilidade, prontid˜ao e sentido de apoio em todas as circunstˆancias, aos quais ficarei eternamente grato. Ao longo deste caminho j´a referido, n˜ao poderei esquecer alguns dos professores que tamb´em me marcaram nesta caminhada, em especial os Professores Doutores Ant´onio Gouveia, Benjamim Fonseca, Leonel Morgado, Lu´ıs Filipe Barbosa, Paulo Martins e V´ıtor Filipe.
Tamb´em desejo nesta altura deixar uma palavra de agradecimento particular ao Sr. Professor Doutor e Director deste mui nobre curso Ramiro Gon¸calves, pelo apoio e optimismo sempre demonstrados em rela¸c˜ao `a minha pessoa.
`
A grande Institui¸c˜ao – Universidade de Tr´as-os-Montes e Alto Douro (UTAD) – e ao Departamento de Engenharias da UTAD deixo os meus maiores agradecimentos, porque me acolheu durante estes anos e permitiu que chegasse a esta concretiza¸c˜ao. N˜ao poderei deixar passar esta etapa sem agradecer, com carinho, ao INESC TEC, bem como `a FCT. Muito obrigado.
A todos os meus amigos, relembrando Ricardo Rodrigues Nunes, Gon¸calo Matos, Daniela Pedrosa, Wallace Ugulino, Wellisom Souza, Jo˜ao Alves, Ricardo Vilela, Tiago Rodrigues, Guilhermino Morais, R´uben Monteiro, Ana Martins, M´arcia Guerra, Pedro Martins, Yasmim Yamaguchi, Alexander, Rolland, Pedro Gon¸calves, Miguel Melo, Telmo Ad˜ao, Filipe Marques e Rui Silva.
Que me perdoem todos aqueles que eventualmente me tenha esquecido de referir, que estar˜ao sempre no meu cora¸c˜ao.
Finalmente, `a minha fam´ılia, que me apoiou em todas as circunstˆancias.
A todos, um muito obrigado! Lu´ıs Miguel Alves Fernandes
Junho 2016
UTAD, Vila Real 29 de Junho, 2016
General Index
Abstract ix
Resumo xi
Acknowledgments xiii
Agradecimentos xv
Table Index xxi
Figure Index xxiii
Glossary, acronyms and abbreviations xxv
1 Introduction 1
1.1 Context . . . 1
1.2 Motivations . . . 2
1.3 Main Contributions and Goals . . . 3
1.4 Document organisation . . . 5 2 Navigation Systems 7 2.1 Concept . . . 7 2.2 Introduction . . . 7 2.3 Blind Navigation . . . 9 xvii
2.3.1 Research Solutions . . . 10 2.3.2 Commercial Solutions . . . 16 2.3.3 Portuguese Solutions . . . 21 3 Software Architectures 27 3.1 Concept . . . 27 3.2 Introduction . . . 27 3.3 Design Principles . . . 30 3.4 Architectural Styles . . . 31
3.4.1 Benefits & Basic Properties . . . 31
3.4.2 Common Styles . . . 33
3.4.3 Enterprise . . . 39
3.4.4 Mobile Oriented . . . 39
4 Blind Guidance and Navigation Mobile App Specification 41 4.1 Introduction . . . 41
4.2 Travelogue . . . 42
4.3 The CE4Blind Project . . . 44
4.4 Requirements Analysis . . . 46 4.5 Architecture Design . . . 50 5 Architecture Implementation 55 5.1 Introduction . . . 55 5.2 Inception. . . 56 5.3 Design . . . 57 5.3.1 Data Module . . . 57 5.3.2 Interface Module . . . 59 5.3.3 Bluetooth Module. . . 60 5.3.4 Sensors Module . . . 60 5.3.5 Sensor Utilities . . . 61 5.3.6 Core Module . . . 61 5.4 Culmination . . . 63 5.4.1 Asynchronous Programming . . . 64 5.4.2 Communication . . . 65 5.4.3 Design Patterns . . . 65 6 Testing 71 6.1 Introduction . . . 71 6.2 Guidance . . . 72 6.2.1 Assignments . . . 73 xviii
6.3 Navigation . . . 74 6.3.1 Assignments . . . 75 6.4 Interaction . . . 77 6.4.1 Assignments . . . 77 6.5 Discussion . . . 81 7 Final Considerations 83 7.1 Future Work . . . 84 References 85 xix
Table Index
2.1 Overview of localisation techniques in different research solutions . . 15
2.2 Overview of the interaction input in different research solutions . . . 15
2.3 Overview of the feedback modality in different research solutions . . . 16
2.4 Overview of localisation techniques in different commercial solutions . 19 2.5 Overview of the interaction input in different commercial solutions . . 20
2.6 Overview of the feedback modality in different commercial solutions . 21 2.7 Overview of localisation techniques in different Portuguese projects . 24 2.8 Overview of the interaction input in different Portuguese projects . . 24
2.9 Overview of the feedback modality in different Portuguese projects. . 25
5.1 White Cane Menu code translation. . . 59
6.1 Guidance assignments results. . . 74
6.2 Navigation assignments results. . . 76
6.3 Interaction assignments results. . . 80
Figure Index
3.1 Layer architectural style example . . . 34
3.2 Client–Server architectural style example . . . 35
3.3 Blackboard architectural style example . . . 36
3.4 Publish–Subscribe architectural style example . . . 37
3.5 Event–based architectural style example . . . 38
3.6 Peer–to–Peer architectural style example . . . 38
4.1 Blavigator System Architecture . . . 43
4.2 Blavigator Mobile Application internal flow. . . 43
4.3 3D Model of a physical space . . . 45
4.4 Mesh network of points of interest . . . 47
4.5 Packages Architectural View . . . 50
4.6 Instrumented white cane. . . 51
5.1 Architecture Class Diagram . . . 58
5.2 Consumption Mode Class Diagram . . . 63
5.3 Bootstrap Example Class Diagram . . . 66
5.4 Menu Class Diagram . . . 67
5.5 Database Module in–depth Class Diagram . . . 69
6.1 Guidance Scan example . . . 74
6.2 Navigation routes example . . . 75
6.3 Virtual menu representation . . . 77
Glossary, acronyms and
abbreviations
Acronyms list
Acronym Expansion
UTAD University of Tr´as-os-Montes and Alto Douro
INESC TEC Institute for Systems and Computer Engineering, Technology and Science
FCT Foundation for Science and Technology GPS Global Positioning System
RFID Radio–Frequency Identification
CE4Blind Context Extraction for the Blind using computer vision QR code Quick Response code
NASA National Aeronautics and Space Administration USA United States of America
GNC Guidance, Navigation and Control system IMU Inertial Measurement Units
UAV Unmanned Aerial Vehicles
Acronym Expansion
MoBIC Mobility of Blind and Elderly people Interacting with Com-puters
MOPS MoBIC Pre–journey System GIS Geographical Information Systems MOODS MoBIC Outdoor System
MOTA MoBIC Travel Aid
UCSB University of California Santa Barbara CMU Carnegie–Mellon University
PGS Personal Guidance System
DGPS Differential Global Positioning System POI Point of Interest
OEM Original Equipment Manufacturers
3D Three–dimensional
VR Virtual Reality
AR Augmented Reality
MCU Microprocessor Unit
GPRS General Packet Radio Service
IoT Internet of Things
BLE Bluetooth Low Energy
IBIS Integrated Board Information System API Application Programming Interface NPO Non–Profit Organisation
RLSB Royal London Society for Blind People ATM Automated Teller Machine
ANSII American National Standards Institute
IEEE Institute of Electrical and Electronics Engineers ISO International Organisation for Standardisation
Acronym Expansion
IEC International Electrotechnical Commission
LoD Law of Demeter
DRY Don’t Repeat Yourself BDUF Big design upfront AI Artificial Intelligence
RPC Remote Procedure Call
P2P Peer–to–Peer
CPU Central Processing Unit
UI User Interface
UT Austin University of Texas in Austin
ACAPO Portuguese Association of Blind and Partially Sighted ORC Optical Character Recognition
LCD Liquid–Crystal–Display NFC Near field communication
TTS Text–to–Speech
GSM Global system for mobile communication GUI Graphical User Interface
CLR Common Language Runtime
ORM Object Relational Mapping JSON JavaScript Object Notation IoC Inversion of Control
CRUD Create, Read, Update and Delete I&T Integration Testing
Abbreviations List
Abbreviation Meaning(s)
e.g. from latin exempli gratia; for example et al. from latin et alii ; and others (co–authors) i.e. from latin id est ; that is
ca. from latin circa; approximately cf. from latin confer ; see also
1
Introduction
1.1
Context
Within the overall population with visual impairments, about 90% of the world’s visually impaired live in developing countries and 82% of people living with blind-ness are aged 50–years–old and above. Regrettably, this percentage is expected to increase in the coming decades. Visual impairment has a significant impact on individuals’ quality of life, including their ability to work and to develop personal relationships. Almost half (48%) of the visually impaired feel “moderately” or “com-pletely” cut off from people and things around them (Hakobyan et al.,2013). Human beings have the ability to acquire and use information obtained from the sur-rounding environment using their natural sensors. They have developed a number of evolutionary mechanisms that allow the distinction between different objects and the triggering of events and complex processes based on their perception of reality. However, physical environments are evolving faster and faster and this momentum introduces new obstacles and challenges in daily lives of the blind. Assistive tech-nology plays an important role in the life of people with disabilities to accomplish daily living tasks and assists them in communication, education, work and recre-ation activities, enhancing their autonomy. In spite of the help provided, traditional
2 CHAPTER 1. INTRODUCTION
assistive technology still has a long way to go: blind navigation systems are mostly based on Global Positioning System (GPS) which is restricted to outdoor usage; au-dio signage systems depend on the update and availability of the information and location accuracy; talking labelling systems require a specific device for locating objects and do not associate them with their locations or day-to-day activities.
To address the task of finding the user location in indoor environments several techniques and technologies have been used (e.g., sonar, radio signal triangulation, radio signal (beacon) emitters, or signal fingerprinting). All these technologies can be and have been used to develop systems that help to enhance the personal space range of blind or visually impaired users (Strumillo, 2010).
Some research teams (Willis and Helal,2005;D’Atri et al.,2007;Chumkamon et al.,
2008), have developed navigation systems based on this technology. In outdoor en-vironments, some hybrid systems using GPS as the main information source and Radio–Frequency Identification (RFID) for correction and location error minimisa-tion have been proposed. In the last few years, the research team at the University of Tr´as–os–Montes and Alto Douro (UTAD) has given major focus to visual impair-ment and on how existing technology may help in everyday life applications.
1.2
Motivations
In order to overcome or lessen the difficulties posed by visual impairment, extensive research has been dedicated to building assistive systems. The need for assistive technologies has long been constant in the daily lives of people with visual impair-ment, and will remain constant in future years. Traditional assistive technologies for the blind include white canes, guide dogs, screen readers, and so forth. Modern mo-bile assistive technologies are becoming more discrete and include (or are delivered via) a wide range of mobile computerised devices, including ubiquitous technologies like mobile phones. Such discrete technologies can help alleviate the cultural stigma associated with the more traditional (and noticeable) assistive devices (Trust,2003).
1.3. MAIN CONTRIBUTIONS AND GOALS 3
Nothing can ensure that a certain physical space surrounding a person is an absolute and constant reality. Either due to structural needs (e.g., projects, traffic) or by changes in nature that require the adequate adaptation to circumstances - sometimes urgently - can automatically imply the change of what are considered common paths, which for people with deficiencies will always be a greater limitation that can even endanger their locomotion.
In addition to natural limitations of a physically limited person (in this case, blind or partially sighted people), the itinerary they usually take can have the difficulties described above, and thus the need of taking advantage of these serious gaps to develop new assistive technologies and ongoing support to these people with greater difficulties.
Over the years, the navigation and guidance systems have shown a great evolu-tion in terms of traffic/transport (means itself) and for people without disabilities to help them find one or the other point of interest in their day–to–day. However, this trend is not yet reflected in the same level of expansion with regard to people with visual impairments, and as such, the research done in the area, although with already a great merit, deserves to be supported and encouraged in both a philan-thropic and state level, not only financially but also with the construction or reuse of facilities/buildings, scholarships and, above all, with a great sense of spirit, sup-port and permanent interest in the sense of a constant search to improve the quality of life of everyone.
1.3
Main Contributions and Goals
This dissertation is part of CE4Blind project and aims to build upon the advan-tages of the latest technological developments to create innovative solutions that can strongly contribute to the support and inclusion of people with special needs, specif-ically the blind community and all people suffering from visual impairment. The dissertation focuses on the conceptualisation of a sufficiently robust architecture to support a digital mobile platform (CE4Blind) which consequently can contribute
4 CHAPTER 1. INTRODUCTION
to an increase in the autonomy and range of action of the visually impaired, al-lowing inclusion in a broader set of activities and enhancing the quality of life. Visually impaired people face great challenges in their day–to–day lives that often require the regular help and support of others. Whether in an indoor environment going about daily activities, or an outdoor environment moving from one location to another, challenges faced can lead to a deep sense of isolation and dependency. Using computer vision techniques and enabling technologies, it is possible to inte-grate knowledge and know–how from a variety of fields including Art (design and fabrication), Digital Media (information and platforms), mathematics (algorithms), Computer Science (hardware and software), and Engineering. Resulting integrated solutions could include automatic text reading, recognition of barcodes and quick response codes (QR code) (e.g., drugs or packaged foods), and the recognition of specific objects, enabling a significant increase in autonomy and allowing end users to better navigate in both indoor and outdoor environments. Feedback given to the blind pedestrians can also be much more humanised and thoughtful preventing their cognitive overload – phenomenon also known as masking (Ugulino and Fuks,2015). The University of Tr´as–os–Montes and Alto Douro has a well-known background on research in the assistive technologies domain. Blind users’ orientation and nav-igation have been a hot research topic and many projects have been conducted to explore technologies to enhance the autonomy of blind people. The CE4Blind project aims to enhance and reuse previous technologies, developing an innovative mobile application for blind users’ orientation and navigation. Since the final goal is to help blind pedestrians in their daily activities, taking coherent real-time decisions becomes the most important requisite and thus, the solution software architecture, which is the main focus of this dissertation, should start by allowing the ease inte-gration of new technologies and sensors such as GPS, RFID, computer vision and Bluetooth–enabled beacons and combining their data feed to make decisions in a more informed way and be able to achieve better results when using the system in a real context.
1.4. DOCUMENT ORGANISATION 5
1.4
Document organisation
Navigation and Guidance systems are on their own, and originally, considered com-plex. Likewise, their architectures require a large conceptualisation and study, and thus the present work is structured to present all this process the clearest and logi-cally possible, as further discriminated:
• Chapter 2 -Navigation Systems :
presentation of the general concept of navigation as well as its use and its historical foundations. Some of the relevant research projects in the area, some solutions already on the market (not necessarily commercial) and some national solutions (i.e., Portugal) are also described;
• Chapter 3 -Software Architectures :
presentation of the overall architectural concept and its adaptation to the area of computing, as well as the considered principles and requirements in the conceptualisation and design of a software architecture;
• Chapter 4 -Blind Guidance and Navigation Mobile App Specification : presentation of the work already done by the UTAD research group that are the building blocks of the new project (CE4Blind) requirements and consequently in the architecture design of the solution;
• Chapter 5 -Architecture Implementation :
presentation of implementation of a proof of concept based on the conceptu-alised architecture and technologies available for that purpose;
• Chapter 7 -Final Considerations :
presentation of the key points of this dissertation, as well as encouragement of future investments.
2
Navigation Systems
2.1
Concept
Etymologically (cf., Oxford English Dictionary1), navigation derives from the Latin
navigatio(n-), based on the verb navigare ‘navigate’ and defined as “the process or activity of accurately ascertaining one’s position and planning and following a route”. The verb navigate (navigare) can then be split into navis ‘ship’ and agere ‘drive’, and is defined as “plan and direct the course of a ship, aircraft, or other form of transport, especially by using instruments or maps”.
2.2
Introduction
Since ancient civilisations (e.g., from which Phoenice can be highlighted, who used the Mediterranean to leverage new potentials), who deeply influenced the known modern era, that navigation has been implicitly present. Whether due to surviv-ability, emergency or basic needs, Man has always embraced the strategy of using “what they have on hands”, using for that everything nature had to offer, namely
1 http://oxforddictionaries.com/
8 CHAPTER 2. NAVIGATION SYSTEMS
the Sun itself, the stars (e.g., Polar Star on the Northern Hemisphere and the South-ern Cross on the SouthSouth-ern Hemisphere), natural satellites (e.g., Moon), as well as in daily living, the trees, river orientation, location of animals nests – which were a sign of bad lashing/punishing weather, for better protection – the ocean tides and, in modern times, the geographic orientation provided by religious buildings (e.g., catholic churches with the altar facing east).
Portugal might be mentioned as an example of discovery and innovation in the guid-ance field, if we remember its role on Land and Maritime Discoveries (e.g., in Africa, Asia and America), starting on the XV Century, with astonishing commitments for that age regarding Nautical constructions, allied to the Navy techniques and tools such as the Astrolabe and Jacob’s Staff that were already in use, and later, even for remembering the great mathematician Pedro Nunes, also Portuguese, the Nonius, another noteworthy navigation tool.
History keeps showing that guidance and navigation are essential. At a closer look, one can notice, for example, that during World War II one of the first guidance systems was used – a German guided missile, known primarily as flying bomb, but also referred to as the V1, buzz-bomb, doodle-bug or robot bomb (Vanek,1999, p. 123), whose guidance system consisted of a gyroscope to maintain the direction, airspeed sensors, and an altimeter, considering the target’s characteristics (i.e., height, speed, etc.).
Later, on a report regarding the Apollo program taken by the National Aeronautics and Space Administration (NASA) of the United States of America (USA), prob-lems regarding the guidance, navigation and control of the Apollo manned lunar landing mission (Draper et al., 1965) are thoughtfully discussed. In the same re-port, guidance is described as “the process of collecting and applying information for the purpose of generating maneuver commands to control vehicle movements”. This process is implemented by the device(s) that constitute a guidance system, which in turn is usually part of a Guidance, Navigation and Control system (GNC), in order to control any vehicle or moving object (Grewal et al., 2007, p. 21). In the abbreviation GNC, navigation represents the systems required to calculate the cur-rent position and orientation based on sensors such as compasses, Global Positioning
2.3. BLIND NAVIGATION 9
Systems (GPS), inertial measurement units (IMU), etc., as the vehicle maneuvers along a trajectory (Farrell,2008, p. 5). Since then, GNC systems have been applied in the movement control of several means of transport (e.g., automobiles, planes).
Nowadays, new autonomous and semi-autonomous valences, where this type of sys-tems GNC are subjacent, are emerging, namely driverless cars (e.g., Google, Tesla) and drones (i.e., unmanned aerial vehicles – UAV) are used not only by several world intelligence agencies but also by civilians (e.g., for photography, topography).
More than ever, these concepts can and should be applied to serve the people, especially those with special cares. Why not use the techniques mentioned earlier to improve the life quality of the people that need special attention? This chapter begins by describing scientific projects that give a shape to some of the concepts addressed, with the primary aim of aiding in orientation and navigation of blind or visually impaired (Section 2.3.1) and subsequently present an overview of their characteristics (Section 2.3.1.9). Similarly, a few projects already in production (commercial or not) or in an experimental phase (Section 2.3.2) and their overview (Section 2.3.2.6) are presented, eventually closing the chapter by outlining some Portuguese solutions that have come to deserve emphasis (Section 2.3.3), as well as their characteristics summary (Section 2.3.3.5).
2.3
Blind Navigation
Naturally, any scientific discovery will have as its ultimate goal not only the inven-tor’s personal and professional fulfilment but also his financial realisation. Ethically, the latter will always be of lower importance when compared to the other two, since the employment of one’s own discovery and consequent improve-ments in the living standards of the population, will always be a greater good to which any scientist cannot remain indifferent during his entire lifetime. The solu-tions presented in section2.3.1, have been created a few years ago and only recently have been given more objective focus, with the watchful eye of several companies who are now adopting these ideas (Section2.3.2), going towards a greater consensus,
10 CHAPTER 2. NAVIGATION SYSTEMS
impact and promising results for blind or partially sighted people.
2.3.1
Research Solutions
Never calling into question the worthiness of all researchers, philanthropy has ulti-mately always been an important aid that still motivates the pursuit of new solu-tions. One such example is the Champalimaud Foundation2, whose founder/mentor
Ant´onio Champalimaud, donated, in a detached way, huge bulks of money for re-search in health, particularly for diseases related to vision, oncology, etc. Today, the said foundation has also launched competitions/awards at the vision field.
In this subsection, the eight scientific solutions for guidance and navigation of blind or partially sighted people whose articles are the most cited are presented, opting for their indication and subsequent arrangement in a chronological way.
2.3.1.1 NavBelt
Shoval et al. (1994, 1998) present NavBelt system starting from the comparison between a mobile robot navigating and a blind traveller, arguing that even if both have locomotion capacity, they both need a sensorial system that can grant obstacle and other hazards detection timely in order to help them avoiding those. In this particular case, the system, which was designed for two operational modes, detects these obstacles using ultrasonic sensors placed within a belt in the form of warning sounds (Guidance Mode) or through the construction of acoustic images (Image Mode), a concept introduced by Loomis et al. (1990). In this latter concept, sound signals seem to sweep through the user’s head from the right ear to the left, where the direction is indicated by the perceived spatial direction of the signal, and the distance is represented by its volume.
2.3. BLIND NAVIGATION 11
2.3.1.2 MoBIC
Mobility of Blind and Elderly people Interacting with Computers, or MoBIC, is a travel aid system developed by Petrie et al. (1996) based on GPS with the objec-tive of increasing the blind and visually impaired mobility in outdoor environments. Before starting the navigation, the travel plan must be defined in a different com-ponent, MoBIC Pre–journey System (MOPS), which uses the Geographical Infor-mation Systems (GIS) as a base. This plan feeds another component, the MoBIC Outdoor System (MOODS), responsible for helping with the guidance and naviga-tion of the users during the already defined route through speech indicanaviga-tions. These two components are interrelated and form MoBIC Travel Aid (MOTA), which is described by the authors as a complementary to primary mobility aids such as the white cane or guide dog.
2.3.1.3 GuideCane
The GuideCane is yet another navigation system, proposed byBorenstein and Ulrich
(1997), designed to help blind or visually impaired travellers through the use of a long handle and a sensor unit attached at its distal end. Despite being heavier when compared to a regular white cane, it rolls on wheels that support that weight, while using ultrasonic sensors and a compass to navigate safely and rapidly among obstacles and other hazards. This system is purely an aid on the go, allowing the user to operate a small joystick with his thumb in order to specify the desired direction of motion; however, it could be further enhanced with GPS to calculate and follow said routes.
2.3.1.4 UCSB & CMU
In a collaboration between University of California Santa Barbara (UCSB) and Carnegie–Mellon University (CMU), (Golledge et al., 1998; Loomis et al., 1998) have built a Personal Guidance System (PGS) based on a Geographical Information System that can act as a database for use on the go by blind and vision–impaired
12 CHAPTER 2. NAVIGATION SYSTEMS
travellers (Golledge et al.,1991). The system consists of three interrelated modules, where the first gives use to, asCollins(1985);Loomis et al.(1994) suggest, a Differ-ential Global Positioning System (DGPS) and a compass in order to, respectively, determine the user location and head orientation. According to these studies, us-ing neither a DGPS nor a compass results in a slower navigation and in a bigger distance covered by the traveller. Based on a GIS and consequently on a digitised base map, the second module is responsible for tracking the navigation path, select routes, and tell the traveller about surrounding points of interest (POI). The third and last module is the interface between the system and the user, providing a two– way communication through a speaker or earphone, or a virtual acoustic display using binaural earphones which give a (better) spatial perception of the location of a specific POI (Loomis et al.,1990).
2.3.1.5 Drishti
Ran et al. (2004) developed a dynamic navigation system for the visually impaired people named Drishti. Unlike many other guidance systems, it doesn’t work only on indoor or outdoor; it’s a dynamic system that can adapt itself to the change between indoor and outdoor environments recurring to a simple voice command de-tected by IBM’s ViaVoice. The use of this system in both situations is due to the use of high precision tracking systems. While on outdoor, based on the ideas of
Loomis et al. (1994); Makino et al. (1996), it uses a Differential Global Position-ing System (DGPS) to keep the user the most closer he can get to the centre of the sidewalks, while inside buildings (indoor), it relies on a system of tracking of-fered by a Original Equipment Manufacturers company (OEM), Hexamite, based on ultrasound obtaining an accuracy of about 22cm. Having also as a base a Spa-tial Database, with Geographical Information Systems (GIS) datasets, the system accompanies the user, helping him with the route to follow and warning him of possible obstacles (present on this same database).
2.3. BLIND NAVIGATION 13
2.3.1.6 Hub
The system presented by (Hub et al.,2004) attempts to assist blind users in orienting themselves in indoor environments with the use of a sensor, which can be integrated with a common white cane to ensure the same feeling of safety, though it should be held and operated just like a flashlight.
The sensor consists of a stereo camera, which does the matching between the cap-tured information and pre–built three dimensional (3D) models of the environment available in a server, with a specific object, whereas a keyboard (the sensor’s han-dler) serves as the communication between the user and the device, which replies to the enquiries (i.e., pressed keys) through a loudspeaker or an earphone.
2.3.1.7 Virtual Leading Blocks
Amemiya et al. (2004) present a system based on Virtual Reality (VR) and Aug-mented Reality (AR) defending that these technologies have high potential to sup-port people with disabilities by augmenting their sensations. Specifically, this system consists of a Finger–Braille wearable interface designed in a previous work (Hirose and Amemiya,2003) which informs the users of their direction and position. Origi-nally, Finger–Braille was invented for Deaf–Blind people and is commonly used by them in Japan as a means to obtain textual information as if they were listening in real time.
This system is also based on a traditional game known as “Watermelon Splitting”, where a blindfolded person tries to hit and cut a watermelon using as a guide both verbal (e.g., “right”) and nonverbal (e.g., “right, right, right...”) instructions, depending on his orientation and position, given by the people surrounding him. Analogously, in the presented system, virtual navigators are used, namely a wearable computer and an ubiquitous environment, with the purpose of guiding the user from the location provided by Radio–frequency identification (RFID) tags placed on the floor and communicating it through verbal instructions then translated to Finger– Braille method.
14 CHAPTER 2. NAVIGATION SYSTEMS
2.3.1.8 Chumkamon
Despite the existence of various forms indoor location based on signal strength or triangulation (Bahl and Padmanabhan, 2000; Youssef et al., 2003), they are prone to space changes and reflection problems, especially when used outside controlled environments, while RFID tags are considered both technically and economically feasible (Willis and Helal,2005). With this in mind,Chumkamon et al.(2008) avoid inaccurate location techniques and present an indoor RFID–based system for blind or visually impaired people, relying on the communication between the navigation device, a Microprocessor Unit (MCU) and a RFID reader, and a navigation server through General Packet Radio Service (GPRS). The latter is fed with the location information provided by each detected tag embedded in the ground to calculate the shortest route to a chosen destination, communicating the result back to the navigation device which should then guide the user using voice through headphones.
2.3.1.9 Discussion
The tables herein, based onFallah et al.(2013), respectively summarise the location techniques (cf., Table 2.1), the interaction input types (cf., Table 2.2) and the feedback modalities (cf., Table2.3) of the guidance and navigation systems presented in the preceding subsections, stressing that the information from these tables meets what is disclosed by the authors own articles.
2.3. BLIND NAVIGATION 15
Solution Technique
GPS RFID Computer Vision Ultrasound
NavBelt X
MoBIC X
GuideCane X
UCSB & CMU X
Drishti X X
Hub X
Virtual Leading Blocks X
Chumkamon X
Table 2.1 – Overview of localisation techniques in different research solutions
The table above shows a higher incidence or trend before the year 2000 in the use of ultrasound for indoor and GPS for outdoor, whereas subsequently the use of RFID for closed environments (indoor) is favoured relatively to ultrasound.
With regards to the user interaction methods with the systems, the table below illustrates the ones which granted such interactions.
Solution Input Types
Keypad Speech Recognition
NavBelt
MoBIC X
GuideCane
UCSB & CMU X
Drishti X
Hub X
Virtual Leading Blocks Chumkamon
Table 2.2 – Overview of the interaction input in different research solutions
Among the various existing forms of feedback (e.g., visual, haptic, speech, audio cues), the systems presented favour (cf., Table 2.3, below), the use of haptic or speech.
16 CHAPTER 2. NAVIGATION SYSTEMS
Solution Modality of feedback Haptic Speech
NavBelt X
MoBIC X X
GuideCane
UCSB & CMU X
Drishti X
Hub X
Virtual Leading Blocks X
Chumkamon X
Table 2.3 – Overview of the feedback modality in different research solutions
2.3.2
Commercial Solutions
Apparently, and over the years, companies have come to believe in the research done in this area, naturally with all the resulting economic and financial involve-ment, knowing that any partnerships in an altruistic level, or other, will always tend to a profit. Yet, this kind of entrepreneurship should be praised, regardless of whether or not having a support from the State’s budget, or from philanthropy as the remarkable case of the Champalimaud Foundation, already mentioned before.
In this subsection, some projects considered relevant in the area which have been put to practice in real contexts, such as in the access and use of public transports (e.g., subways, buses) are presented.
2.3.2.1 BlindSquare
BlindSquare3 is an iOS only (i.e., iPhone and iPad devices) solution for the blind and visually impaired, which uses GPS location to describe the environment as the user travels past points of interest. The information look-up is performed through
2.3. BLIND NAVIGATION 17
open–source software (Fourquare4 and Open Street Map5) and is then voiced using a dedicated speech synthesiser. Typically paired with a headset or Bluetooth speaker, this app allows users to track their progress toward a destination through periodic announcements of distance and direction while travelling. The announcements are spaced out so the user does not get overwhelmed with more information than needed.
2.3.2.2 Ifinity
Established in 2015, Ifinity6 is a start–up company, active in the market of Internet of Things (IoT), which believes that “cities should be equally accessible to every-one”. The company was selected as the technology provider and mobile application designer for Virtual Warsaw, a project designed to facilitate mobility for the visu-ally impaired through the use of Bluetooth–equipped beacons. In a few years’ time, the goal is to supply the city’s population with contextual real-time information on public transport, indoor navigation, and tourist attractions. By creating an addi-tional layer to the city made purely of data - a digital grid, accessed with both base and third–party mobile applications through Bluetooth Low Energy (BLE) - the city will be available to the blind in a way it never has been before.
2.3.2.3 GeoMobile - Ivanto
GeoMobile7 is a service provider specialising in mobile accessible assistance systems. Founded in 2008, GeoMobile focuses on accessibility design and usability engineer-ing which has been gainengineer-ing attention and traction over the last few years. One of their solutions, Ivanto8, is a cost efficient system looking to improve and
rede-fine accessibility and inclusion in public transports by turning vehicles and station buildings into smart things – Internet of Things for urban mobility. A communi-cation and control unit, ivantoCore, is connected to the board computers of buses
4 https://foursquare.com/
5 https://www.openstreetmap.org/ 6 http://getifinity.com/
7 http://geomobile.de/home-en/ 8 http://ivanto.de/?l=en
18 CHAPTER 2. NAVIGATION SYSTEMS
and trams, decoding the Integrated Board Information System (IBIS) protocol mes-sages from the vehicle and broadcasting them via Bluetooth to passenger’s smart-phones (through ivanto Application or third–party solutions using their Application Programming Interface (API)), which allows them to send service requests back re-motely (e.g., stop trigger). Additionally, this system provides a Bluetooth beacon infrastructure within station buildings in order to further aid visually impaired and blind people mobility.
2.3.2.4 Wayfindr
Wayfindr9 is a non–profit organization (NPO) and joint venture between Royal Lon-don Society for Blind People10 (RLSB) and ustwo11 founded in 2014 with the goal
of empowering vision impaired people to overcome isolation through audio–based navigation. They started doing so in Pimlico Station, London, using Bluetooth Low Energy (BLE) beacons triangulation to locate a user’s smartphone through an installed application, and are now expanding to larger stations to help the blind navigate the Tube independently. In order to have a greater impact globally, how-ever, there is a pressing need of developing a consistent and inclusive standard to be implemented all around the world, leading to the creation of an Open Standard. Vision impaired people and blind people are no longer held back by their lack of sight as this standard provides tools to venue owners and digital navigation services to implement high quality wayfinding systems across the globe.
2.3.2.5 Cities Unlocked - 3D SoundScape
The Cities Unlocked12 project is a collaboration between GuideDogs13 and
Mi-crosoft14to develop a headset, known as 3D SoundScape, which enables blind people
9 https://wayfindr.net/ 10 http://rlsb.org.uk/tech-hub 11 http://ustwo.com/ 12 http://citiesunlocked.org.uk/ 13 http://guidedogs.org.uk/ 14 https://microsoft.com/
2.3. BLIND NAVIGATION 19
to navigate unaided. The headset contains a GPS, a gyroscope, compass and ac-celerometer sensors as well as bone conduction, which converts the sound waves into vibrations that go straight through the skull, skipping the eardrum to get in the in-ner ear. When connected via Bluetooth to the wearer’s smartphone application, the headset signals turn–to–turn directions in order to follow a route plotted on Bing Maps15 through voice commands, while also providing enhanced contextual
infor-mation (e.g., points of interest) and picking up real–time inforinfor-mation and cues from installed Bluetooth and Wi–Fi–enabled beacons dotted along the route.
2.3.2.6 Discussion
The tables in this subsection, based on Fallah et al. (2013), respectively summarise the location techniques (cf., Table 2.4), the interaction input types (cf. Table 2.5) and the feedback modalities (cf., Table 2.6) of the guidance and navigation systems commercial presented throughout the preceding subsections, stressing that the infor-mation from these tables meets what is exclusively published on the corresponding websites. In addition, it is necessary to safeguard the contribution in each season since, of course, over the years, new technologies and concepts have emerged, “which obviously did not exist before being created or thought” - you can not compare the incomparable because of being ungrateful doing so.
Solution Technique
GPS RFID Computer Vision Ultrasound Beacons
BlindSquare X
Ifinity X
GeoMobile X
Wayfindr X
Cities Unlocked X X
Table 2.4 – Overview of localisation techniques in different commercial solutions
20 CHAPTER 2. NAVIGATION SYSTEMS
As shown in the table above (cf., Table 2.4), in contrast with the scientific projects presented throughout the sections 2.3.1 and 2.3.1.9, whose most used indoor lo-cation technique was ultrasound, the most recent systems prefer triangulation by Bluetooth–enabled Beacons, a technique which started to become more notice-able since 2010 - year of the merge of Bluetooth Smart, originally introduced in 2006 under the name Wibree16 by Nokia, into the main Bluetooth Standard with
the adoption of Bluetooth 4.0. With regards to outdoor systems, the trend contin-ues in the preferential use of GPS, although the (scientific) projectsUCSB & CMU
(Golledge et al., 1998; Loomis et al., 1998) and Drishti (Ran et al., 2004) utilised a specific variant of this technology: DGPS, an enhanced version that provides improved location accuracy.
Likewise, the evolution of technology has also influenced the interaction methods with these systems (cf., Table 2.5), as with the emergence of smartphones, which started to become prevalent in the XXI century, these have come to dictate the means of interaction.
Solution Input Types
Speech Recognition Bluetooth Speaker Smartphone
BlindSquare X X
Ifinity X
GeoMobile X
Wayfindr X
Cities Unlocked X X
Table 2.5 – Overview of the interaction input in different commercial solutions
2.3. BLIND NAVIGATION 21
With regard to the feedback modalities, which remain the same, there is still (cf., Table 2.6) a predominance in the use of speech.
Solution Modality of feedback Haptic Speech BlindSquare X Ifinity X GeoMobile X Wayfindr X Cities Unlocked X
Table 2.6 – Overview of the feedback modality in different commercial solutions
2.3.3
Portuguese Solutions
At the national level (i.e., in Portugal), projects with significant interest have been emerging, which will bring added value to the quality of life of blind and visually impaired citizens over time. In the following subsections, the usefulness of a few of these solutions is conferred.
2.3.3.1 Guio
Sonae Sierra17, the international shopping centre specialist, released in 2011 a patented
system Guio R Solid Step18in its Columbus and NorteShopping centres (Lisbon and
Porto respectively), a solution to guide and inform blind and partially sighted peo-ple during their visits. Guio was developed by Moniz Dias19 in collaboration with Sonae Sierra and consists of fixed units installed at strategic points throughout the mall providing information (e.g., store description, location of bathrooms, emer-gency number , etc.) in MP3 (MPEG–1 or MPEG–2 Audio Layer III) format via Bluetooth to small portable units called “BeepM´ovel” then made available via audio according to the user request, through a button interface, and location of users.
17 http://sonaesierra.com/corporate/en-gb 18 http://guio.pt/solidstep/solidstep.html 19 http://monizdias.pt/
22 CHAPTER 2. NAVIGATION SYSTEMS
2.3.3.2 NAVMETRO
NAVMETRO R (Ferreira, 2013), in force at Trindade’s subway station in Oporto since 2009, aims to help the blind and partially sighted users in their mobility and autonomy within this shuttle service. To use this system, the person must call a provided toll–free number and, through the use of voice, follow the directions given by the central automated attendant, namely to select the desired destination. Since the system also needs an initial reference point, one of the given instructions is to point out the closest - audible - speaker, already part of the subway infrastructure, from the user’s current location. The person then is guided by following the sound of birds coming from the existing speakers throughout the chosen route, and when crossing/arriving near one of them, the user needs to communicate it to the system using his voice (interpreted by the central using voice recognition), so that the central turns on the next route speaker and the user continues following the sound.
2.3.3.3 SmartGuia
SmartGuia is a system that aims to help the blind and partially sighted users in their visits to stores, shopping centres, etc., through a smartphone application that offers assistance in navigating in these locations (indoor), responding to questions asked (i.e., speech recognition) by users and providing, also through speech and from an information system, the essential information about the spaces, services and products available. Based on the location of the person, which is obtained from triangulations made with Bluetooth or Wi–Fi–enabled Beacons, it can also guide the user to the place where a particular product or service is.
2.3.3.4 SmartVision & Nav4B & Blavigator
In the last few years, the research team at the University of Tr´as–os–Montes and Alto Douro (UTAD) has given major focus to visual impairment and on how existing technology may help in everyday life applications. From an extensive review of the literature and its best practices, three main projects have been developed: the
2.3. BLIND NAVIGATION 23
SmartVision (Du Buf et al., 2011), Nav4B (Fernandes et al., 2011) and Blavigator (Adao et al., 2012) projects.
On the genesis of Blavigator is SmartVision, whose main goal was to aid blind and visual impaired people and improve their navigation autonomy through the development and integration of technology into a small, cheap and easy to assemble portable device – an extension of the white cane, not a replacement. Based on RFID, placed on the ground and used to create electronic trails and tags, and GPS, the device was designed to issue audio, warning signals when approaching an obstacle (e.g., chairs, tables) or hazard (e.g., stairs, elevators), a point of interest (e.g., cash machine - ATM) or when the heading direction should be adapted.
Nav4B extended SmartVision by proposing the integration between blind navigation and day–to–day life supporting information systems such as traffic lights and public transports (e.g., buses, taxis), not forgetting about the ubiquity and ergonomics of the solution which used typical blind aids such as white cane, smartphone and bone conduction headphones.
The Blavigator Project widened the main goals of SmartVision with the concept of Nav4B’s architecture, aiming to be an integrated navigation system which increased the navigation autonomy of those using it while being small, cheap, reliable and easy to use. Its prototype consisted on an instrumented white cane with a RFID reader which communicated, via Bluetooth, with the user’s smartphone which by itself provides a compass, GPS, Internet connection and Bluetooth for interfacing back with the white cane.
2.3.3.5 Discussion
The tables in this subsection, still based in Fallah et al. (2013), respectively sum-marise the location techniques (cf., Table2.7), the interaction input types (cf., Table
2.8) and the feedback modalities (cf., Table2.9) of the guidance and navigation Por-tuguese systems presented, stressing that the information from these tables meets what is exclusively published on the corresponding websites and/or articles. Invari-ably, it will always be necessary to safeguard the normal constraints due to times
24 CHAPTER 2. NAVIGATION SYSTEMS
and research facilities available then.
Solution Technique
GPS RFID Computer Vision Ultrasound Beacons
Guio NAVMETRO SmartVision X Nav4B X Blavigator X X X SmartGuia X
Table 2.7 – Overview of localisation techniques in different Portuguese projects
The research in this particular area is proving increasingly effective, with results in terms of its application in real contexts, trying to facilitate the mobility of blind or partially sighted people. Fortunately, the amount of this type of projects is diverse, which only brings benefits to the users. The location techniques (cf., Table 2.7) and input methods (cf., Table 2.8) used in these systems are varied, and sometimes intermittent, not only due to political/governmental or economic constraints but also due to the interregnum that the evolution of technology has been submitted to. As explained in general terms back in section 2.3.2.6, also at the level of Portugal one can infer that the evolution makes ungrateful comparisons.
Solution Input Types
Keypad Speech Recognition Smartphone
Guio X NAVMETRO X X SmartVision Nav4B Blavigator X X SmartGuia X
Table 2.8 – Overview of the interaction input in different Portuguese projects
With regard to the feedback modalities, it can be seen that despite the same focus on the use of speech (cf., Table 2.9), audio cues are also used, an alternative that is considered feasible since it is not language dependent (Fallah et al., 2013).
2.3. BLIND NAVIGATION 25
Solution Modality of feedback Haptic Speech Audio cues
Guio X NAVMETRO X X SmartVision X Nav4B X Blavigator X X X SmartGuia X
3
Software Architectures
3.1
Concept
Etymologically (cf., Oxford English Dictionary1), architecture derives from the
Latin architectura, from architectus ‘architect’ and is defined as “the complex or carefully designed structure of something”. Architect (architectus) derives from the Greek word arkhitekt˜on which can be split into arkhi- ‘chief’ and tekt˜on ‘builder’, and is defined as “a person who designs buildings and in many cases also supervises their construction”.
3.2
Introduction
In the previous chapter, the concepts of guidance and navigation were presented as well as their roots and evolution to the present day. What began as a basic need of survival and rudimentary, turned out to be something no one can alienate these days, integrating naturally into the society day–to–day. As it is to be expected, from any evolution comes always some complexity, which requires researchers / entrepreneurs
1 http://oxforddictionaries.com/
28 CHAPTER 3. SOFTWARE ARCHITECTURES
to reflect and test new concepts. The challenge begins with the idea of always looking for the best in every circumstance, taking the Humankind to this incessant / insatiable quest. It is possible to make an analogy with idealism advocated by philosophers such as Hegel and Ficht, while acknowledging some exaggeration, which at the level of science remains current in a way, because “dreams should always lead the life”, permanently taking regard to its efficacy and, preferably, its efficiency. The concrete case of guidance and navigation systems, as discussed in the previous chapter (cf., Chapter2-Navigation Systems), has always been a challenge for science and particularly for the technological field, which is, by nature, also very complex. The unveiling of complexity can be supported by the use of architectures, which show to be essential for in the analysis and description of these systems (Garlan and Shaw, 1993, pp. 1–2). The concept of architectures (software–wise) was first drawn in the late 1960s, starting with the comparison between software design and (civil) architecture in 1968 by Naur “software designers are in a similar position to architects and civil engineers” (Naur and Randell,1969), although the true embryo being the study of systems structures carried out by Dijkstra (Dijkstra, 1968) and then by David Parna (Parnas, 1978; Parnas et al., 1984). Thereafter, at the same time, architecture was referred by Brooks and Iverson that defined it as “conceptual structure of a computer (...) as seen by the programmer” (Brooks and Iverson,
1969). Later, Blaauw extends the concept, defining system architecture as “the functional appearance of the system to the user, its phenomenology” (Blaauw,1972), making an analogy with wristwatches and clock towers, whose architecture (i.e., the operation of the hours and minutes hands) is the same, despite its implementation and realisation not being the same: “where the architecture tells what happens, the implementation describes how it is made to happen” (Blaauw, 1972). This distinction is strengthened by Brooks, which in turn alerts the importance of doing a careful separation between architecture and its implementation, so that further additions to the system are aligned with the defined architecture, and thus preserving conceptual integrity (Brooks, 1975, pp. 44–45).
Only in the early 90s, the concept software architecture started to be taken into consideration (Shaw, 1990; Rechtin, 1991; Perry and Wolf, 1992), presenting itself as a way to oppose the new complexity of systems, something considered impossible
3.2. INTRODUCTION 29
with the use of techniques (i.e., data structures) known at the time. Shaw urges, with conviction, the need for new abstraction techniques to solve these problems, describing some of the most popular organisation systems (e.g., pipe and filter, layer, blackboard), and Perry and Wolf present a model of software architecture that consists of three elements: elements, form and rationale, resulting in the following definition: “set of architectural (or, if you will, design) elements that have a particular form” (Perry and Wolf, 1992), where elements can be subdivided in processing, data e connecting elements; form is defined in terms of their relationship and constraints; and the rationale “provides the base of the architecture in terms of the system constraints which most often derive from system requirements” (Perry and Wolf, 1992). Despite apparently using a different language, Perry and Wolf point of view is shared by Garlan and Shaw (Garlan and Shaw, 1993), where the latter reported that the components (elements in Perry and Wolf approach) along with descriptions of their relationships connectors in Perry and Wolf approach -establish an architecture, and that an architectural style “determines the vocabulary of components and connectors that can be used in instances of that style, together with a set of constraints on how they can be combined” – the concept of style was already used, even if still in an insipid manner with the expression “software architecture level of design” (Shaw, 1990).
It should thus be noted that, in a sense, ideas were converging naturally, and it was during that time (ca., 1995) that more attention started to be given to the true meaning of (software) architecture, trying to reach a consensus (Garlan and Perry, 1995), and, finally, in 1996 an increasingly universal vocabulary in this dis-cipline started to settle (Shaw and Garlan, 1996), even considering that architec-tural styles were “becoming the lingua franca of architecture–level design” (Shaw and Clements, 1997). The definition of architecture also gained more strength with the ANSI/IEEE Standard 1471–2000 (IAWGroup et al., 2000), superseded by ISO/IEC/IEEE 42010:2011 (ISO et al., 2011) which currently is fixed as fol-lows: “fundamental concepts or properties of the system in its environment embod-ied in its elements, relationships, and in the principles of its design and evolution”.
30 CHAPTER 3. SOFTWARE ARCHITECTURES
the most agree that software architectures are designed to abstract the complexity of a system, reducing it and enabling a better understanding and analysis of it, where the use of a particular style of architecture, or combination of styles into a single design (Garlan and Shaw, 1993), could lead to more powerful analyses than a general architecture would, because it is focused on techniques that are effective on a particular domain (Allen,1997).
Going from the design of an architecture to its engineering implementation and application is also a big step, that is, in addition to architectures’ design principles (cf., Section3.3) and existing styles (cf., Section 3.4), there are also challenges with regard to enterprise systems (cf., Section 3.4.3), especially when adapted to mobile environments (cf., Section 3.4.4).
3.3
Design Principles
An architecture design should take into consideration some principles in order to meet the “best practises, minimise costs and maintenance requirements, and pro-mote usability and extensibility” (Meier et al., 2008), namely:
• Separation of Concerns, whose objective is to separate the application in areas of responsibility / functionality such as the user interface from the data access. The main benefit of this approach is the potential that this entails, namely being able to correct or optimise the modules in an independent way, without affecting others, and being easier to understand and manage;
• Single Responsibility Principle, where each module or component should only have one responsibility as a single functionality or special feature and can, therefore, be modified or optimised more quickly;
• Principle of least knowledge or Law of Demeter (LoD), where each component or object should have limited knowledge in relation to other units or subcomponents;
3.4. ARCHITECTURAL STYLES 31
• Don’t Repeat Yourself (DRY), whose purpose is not duplicating the func-tionality that is already the responsibility of another component or module;
• Avoid doing a big design upfront (BDUF), if the application requirements are not fully clear or if there is a possibility that these will grow with time, implying going back and thus more labour and time;
• Prefer composition over inheritance, since the inheritance creates depen-dency among parents and children, thus limiting the use of the latter.
3.4
Architectural Styles
In the literature, various definitions of architectural styles are presented, including the identification of components and connectors that can be used to constitute a system according to a set of local or global constraints (Garlan and Shaw, 1993;
Shaw and Clements,1997). More recently, architectural styles are defined as a “col-lection of architectural design decisions” that can be applied in practice in certain contexts or problems (Taylor et al., 2009). The level of specification of this set of rules and decisions is also proportional to the diffusion and respective application of these architectures in real contexts. That is, the more general, the easier it is to adapt them to real scenarios, and vice versa, the more specific, the stricter is their application.
3.4.1
Benefits & Basic Properties
The importance of software architecture styles was noted some time ago by Perry and Wolf (Perry and Wolf,1992), who started comparisons with the building archi-tecture. They begin by stressing the importance of a (general) architectural style from both descriptive and prescriptive points of view. While the descriptive point of view, an architectural style specifies elements/components and their relationship, in a prescriptive point of view, the style constrains the type of elements/components and their relationship, and the same is considered true in software architecture.
