An infrastructure for experience centered agile prototyping of ambient intelligence

Ubiquitous computing poses new usability challenges that cut across design and development. We are particularly interested in "spaces" enhanced with sensors, public displays and personal devices. How can prototypes be used to explore the user's mobility and interaction, both explicitly and implicitly, to access services within these environments? Because of the potential cost of development and design failure, the characteristics of such systems must be explored using early versions of the system that could disrupt if used in the target environment. Being able to evaluate these systems early in the process is crucial to their successful development. This paper reports on an effort to develop a framework for the rapid prototyping and analysis of ambient intelligence systems

The APEX framework: prototyping of ubiquitous environments based on Petri Nets

The user experience of ubiquitous environments is a determining factor in their success. The characteristics of such systems must be explored as early as possible to anticipate potential user problems, and to reduce the cost of redesign. However, the development of early prototypes to be evaluated in the target environment can be disruptive to the ongoing system and therefore unacceptable. This paper reports on an ongoing effort to explore how model-based rapid prototyping of ubiquitous environments might be used to avoid actual deployment while still enabling users to interact with a representation of the system. The paper describes APEX, a framework that brings together an existing 3D Application Server with CPN Tools. APEX-based prototypes enable users to navigate a virtual world simulation of the envisaged ubiquitous environment. The APEX architecture and the proposed CPN-based modelling approach are described. An example illustrates their use.Fundação para a Ciência e a Tecnologia (FCT) - bolsa de doutoramento SFRH/BD/41179/200

Rapid prototyping of ubiquitous computing environments

Ubiquitous computing raises new usability challenges that cut across design and development. We are particularly interested in environments enhanced with sensors, public displays and personal devices. How can prototypes be used to explore the users' mobility and interaction, both explicitly and implicitly, to access services within these environments? Because of the potential cost of development and design failure, these systems must be explored using early assessment techniques and versions of the systems that could disrupt if deployed in the target environment. These techniques are required to evaluate alternative solutions before making the decision to deploy the system on location. This is crucial for a successful development, that anticipates potential user problems, and reduces the cost of redesign. This thesis reports on the development of a framework for the rapid prototyping and analysis of ubiquitous computing environments that facilitates the evaluation of design alternatives. It describes APEX, a framework that brings together an existing 3D Application Server with a modelling tool. APEX-based prototypes enable users to navigate a virtual world simulation of the envisaged ubiquitous environment. By this means users can experience many of the features of the proposed design. Prototypes and their simulations are generated in the framework to help the developer understand how the user might experience the system. These are supported through three different layers: a simulation layer (using a 3D Application Server); a modelling layer (using a modelling tool) and a physical layer (using external devices and real users). APEX allows the developer to move between these layers to evaluate different features. It supports exploration of user experience through observation of how users might behave with the system as well as enabling exhaustive analysis based on models. The models support checking of properties based on patterns. These patterns are based on ones that have been used successfully in interactive system analysis in other contexts. They help the analyst to generate and verify relevant properties. Where these properties fail then scenarios suggested by the failure provide an important aid to redesign.Fundação para a Ciência e Tecnologi

Rapid prototyping of ubiquitous computing environments

Tese de doutoramento em InformáticaUbiquitous computing raises new usability challenges that cut across design and development. We are particularly interested in environments enhanced with sensors, public displays and personal devices. How can prototypes be used to explore the users' mobility and interaction, both explicitly and implicitly, to access services within these environments? Because of the potential cost of development and design failure, these systems must be explored using early assessment techniques and versions of the systems that could disrupt if deployed in the target environment. These techniques are required to evaluate alternative solutions before making the decision to deploy the system on location. This is crucial for a successful development, that anticipates potential user problems, and reduces the cost of redesign. This thesis reports on the development of a framework for the rapid prototyping and analysis of ubiquitous computing environments that facilitates the evaluation of design alternatives. It describes APEX, a framework that brings together an existing 3D Application Server with a modelling tool. APEX-based prototypes enable users to navigate a virtual world simulation of the envisaged ubiquitous environment. By this means users can experience many of the features of the proposed design. Prototypes and their simulations are generated in the framework to help the developer understand how the user might experience the system. These are supported through three different layers: a simulation layer (using a 3D Application Server); a modelling layer (using a modelling tool) and a physical layer (using external devices and real users). APEX allows the developer to move between these layers to evaluate different features. It supports exploration of user experience through observation of how users might behave with the system as well as enabling exhaustive analysis based on models. The models support checking of properties based on patterns. These patterns are based on ones that have been used successfully in interactive system analysis in other contexts. They help the analyst to generate and verify relevant properties. Where these properties fail then scenarios suggested by the failure provide an important aid to redesign.A computação ubíqua levanta novos desafios de usabilidade transversais ao seu desenvolvimento e design. Estamos particularmente interessados em ambientes enriquecidos com sensores, ecrãs públicos e dispositivos pessoais e em saber como podem ser utilizados protótipos na exploração da mobilidade e interação, implícita e explicita, dos utilizadores de forma a acederem a serviços desses ambientes. Devido às potenciais falhas do design proposto e aos elevados custos associados ao seu desenvolvimento, as características destes sistemas devem ser exploradas utilizando versões preliminares dos mesmos dado que estes podem vir a falhar quando implementados no destino, tornando a sua utilização inaceitável. Essas técnicas são necessárias por forma a avaliar soluções alternativas antes de decidir implementar o sistema fisicamente. Isto é crucial para um desenvolvimento com sucesso que antecipe potencias problemas do utilizador e reduza os custos de redesign. Esta tese descreve o desenvolvimento de uma ferramenta para a prototipagem rápida e análise de ambientes de computação ubíqua como suporte à avaliação de designs alternativos. É apresentado a APEX, uma plataforma que junta um servidor de aplicações 3D com uma ferramenta de modelação. Os protótipos baseados na APEX permitem aos seus utilizadores finais navegarem numa simulação 3D do ambiente ubíquo projetado. Desta forma muitas das características do design proposto podem ser experienciadas pelos utilizadores. Os protótipos e respetivas simulações são gerados na plataforma para ajudar os designers/developers a entender como é que os utilizadores podem experienciar o sistema. Os protótipos são suportadas através de três camadas: a camada de simulação (utilizando um servidor de aplicações 3D); a camada de modelação (utilizando uma ferramenta de modelação) e uma camada física (utilizando dispositivos externos e utilizadores reais). A plataforma possibilita aos designers/ developers moverem-se entre estas camadas de forma a avaliar diferentes características do sistema, desde a experiencia do utilizador até ao seu comportamento através de uma analise exaustiva do sistema ubíquo baseada em modelos. Os modelos suportam a verificação de propriedades baseadas em padrões. Estes padrões são baseados em padrões existentes e já utilizados com sucesso, noutros contextos, na análise de sistemas interativos. Eles auxiliam a geração e verificação de propriedades relevantes. O local onde estas propriedade falham sugere um cenário de falha que fornece uma ajuda importante no redesign do sistema.ERDF through the Programme COMPETE and by the Portuguese Government through FCT - Foundation for Science and Technology, project PTDC/EIA-EIA/116069/2009 and by FCT, under the grant SFRH/BD/41179/2007

Modeling and Analyzing Cyber-Physical Systems Using Hybrid Predicate Transition Nets

Cyber-Physical Systems (CPSs) are software controlled physical devices that are being used everywhere from utility features in household devices to safety-critical features in cars, trains, aircraft, robots, smart healthcare devices. CPSs have complex hybrid behaviors combining discrete states and continuous states capturing physical laws. Developing reliable CPSs are extremely difficult. Formal modeling methods are especially useful for abstracting and understanding complex systems and detecting and preventing early system design problems. To ensure the dependability of formal models, various analysis techniques, including simulation and reachability analysis, have been proposed in recent decades. This thesis aims to provide a unified formal modeling and analysis methodology for studying CPSs. Firstly, this thesis contributes to the modeling and analysis of discrete, continuous, and hybrid systems. This work enhances modeling of discrete systems using predicate transition nets (PrTNs) by fully realizing the underlying specification through incorporating the first-order logic with set theory, improving the type system, and providing incremental model composition. This work enhances the technique of analyzing discrete systems using PrTN by improving the simulation algorithm and its efficient implementation. This work also improves the analysis of discrete systems using SPIN by providing a more accurate and complete translation method. Secondly, this work contributes to the modeling and analysis of hybrid systems by proposing an extension of PrTNs, hybrid predicate transition nets (HPrTNs). The proposed method incorporates a novel concept of token evolution, which nicely addresses the continuous state evolution and the conflicts present in other related works. This work presents a powerful simulation capability that can handle linear, non-linear dynamics, transcendental functions through differential equations. This work also provides a complementary technique for reachability analysis through the translation of HPrTN models for analysis using SpaceEx

Integrating behavioural design into the virtual environment development process

A number of specifications formalisms have been developed (or applied) to support the abstract design of the behavioural component of the virtual environment interface. These formalisms subscribe to the philosophy that virtual environments should be viewed as hybrid systems which combine discrete and continuous behaviour. A significant deficiency in designing behaviour in this way is that the designs cannot be directly executed and explored in the same manner as an implementation. This limitation makes it di#cult for a designer to evaluate the suitability of designs. The thesis presents the Marigold toolset which supports two approaches to evaluating behaviour described using the Flownet hybrid formalism

A multi-modelS based approach for the modelling and the analysis of usable and resilient partly autonomous interactive systems

La croissance prévisionnelle du trafic aérien est telle que les moyens de gestion actuels doivent évoluer et être améliorés et l'automatisation de certains aspects de cette gestion semble être un moyen pour gérer cet accroissement du trafic tout en gardant comme invariant un niveau de sécurité constant. Toutefois, cette augmentation du trafic pourrait entraîner un accroissement de la variabilité de la performance de l'ensemble des moyens de gestion du trafic aérien, en particulier dans le cas de dégradation de cette automatisation. Les systèmes de gestion du trafic aérien sont considérés comme complexes car ils impliquent de nombreuses interactions entre humains et systèmes, et peuvent être profondément influencés par les aspects environnementaux (météorologie, organisation, stress ...) et tombent, de fait, dans la catégorie des Systèmes Sociotechniques (STS) (Emery & Trist, 1960). A cause de leur complexité, les interactions entre les différents éléments (humains, systèmes et organisations) de ces STS peuvent être linéaires et partiellement non linéaires, ce qui rend l'évolution de leur performance difficilement prévisible. Au sein de ces STS, les systèmes interactifs doivent être utilisables, i.e. permettre à leurs utilisateurs d'accomplir leurs tâches de manière efficace et efficiente. Un STS doit aussi être résilient aux perturbations telles que les défaillances logicielles et matérielles, les potentielles dégradations de l'automatisation ou les problèmes d'interaction entre les systèmes et leurs opérateurs. Ces problèmes peuvent affecter plusieurs aspects des systèmes sociotechniques comme les ressources, le temps d'exécution d'une tâche, la capacité à d'adaptation à l'environnement... Afin de pouvoir analyser l'impact de ces perturbations et d'évaluer la variabilité de la performance d'un STS, des techniques et méthodes dédiées sont requises. Elles doivent fournir un support à la modélisation et à l'analyse systématique de l'utilisabilité et de la résilience de systèmes interactifs aux comportements partiellement autonomes. Elles doivent aussi permettre de décrire et de structurer un grand nombre d'informations, ainsi que de traiter la variabilité de chaque élément du STS et la variabilité liée à leurs interrelations. Les techniques et méthodes existantes ne permettent actuellement ni de modéliser un STS dans son ensemble, ni d'en analyser les propriétés d'utilisabilité et de résilience (ou alors se focalisent sur un sous-ensemble du STS perdant, de fait, la vision systémique). Enfin, elles ne fournissent pas les moyens d'analyser la migration de tâches suite à l'introduction d'une nouvelle technologie ou d'analyser la variabilité de la performance en cas de dégradation de fonctions récemment automatisées. Ces arguments sont développés dans la thèse et appuyés par une analyse détaillée des techniques de modélisation existantes et des méthodes qui leurs sont associées. La contribution présentée est basée sur l'identification d'un ensemble d'exigences requises pour pouvoir modéliser et analyser chacun des éléments d'un STS. Certaines de ces exigences ont été remplies grâce à l'utilisation de techniques de modélisation existantes, les autres grâce à l'extension et au raffinement d'autres techniques. Cette thèse propose une approche qui intègre 3 techniques en particulier : FRAM (centrée sur les fonctions organisationnelles), HAMSTERS (centrée les objectifs et activités humaines) et ICO (dédiée à la modélisation du comportement des systèmes interactifs). Cette approche est illustrée par un exemple mettant en œuvre les extensions proposées et l'intégration des modèles. Une étude de cas plus complexe sur la gestion du trafic aérien (changement de route d'un avion en cas de mauvaises conditions météorologiques) est ensuite présentée pour montrer le passage à l'échelle de l'approche. Elle met en avant les bénéfices de l'intégration des modèles pour la prise en compte de la variabilité de la performance des différents éléments d'un STSThe current European Air Traffic Management (ATM) System needs to be improved for coping with the growth in air traffic forecasted for next years. It has been broadly recognised that the future ATM capacity and safety objectives can only be achieved by an intense enhancement of integrated automation support. However, increase of automation might come along with an increase of performance variability of the whole ATM System especially in case of automation degradation. ATM systems are considered complex as they encompass interactions involving humans and machines deeply influenced by environmental aspects (i.e. weather, organizational structure) making them belong to the class of Socio-Technical Systems (STS) (Emery & Trist, 1960). Due to this complexity, the interactions between the STS elements (human, system and organisational) can be partly linear and partly non-linear making its performance evolution complex and hardly predictable. Within such STS, interactive systems have to be usable i.e. enabling users to perform their tasks efficiently and effectively while ensuring a certain level of operator satisfaction. Besides, the STS has to be resilient to adverse events including potential automation degradation issues but also interaction problems between their interactive systems and the operators. These issues may affect several STS aspects such as resources, time in tasks performance, ability to adjust to environment, etc. In order to be able to analyse the impact of these perturbations and to assess the potential performance variability of a STS, dedicated techniques and methods are required. These techniques and methods have to provide support for modelling and analysing in a systematic way usability and resilience of interactive systems featuring partly autonomous behaviours. They also have to provide support for describing and structuring a large amount of information and to be able to address the variability of each of STS elements as well as the variability related to their interrelations. Current techniques, methods and processes do not enable to model a STS as a whole and to analyse both usability and resilience properties. Also, they do not embed all the elements that are required to describe and analyse each part of the STS (such as knowledge of different types which is needed by a user for accomplishing tasks or for interacting with dedicated technologies). Lastly, they do not provide means for analysing task migrations when a new technology is introduced or for analysing performance variability in case of degradation of the newly introduced automation. Such statements are argued in this thesis by a detailed analysis of existing modelling techniques and associated methods highlighting their advantages and limitations. This thesis proposes a multi-models based approach for the modelling and the analysis of partly-autonomous interactive systems for assessing their resilience and usability. The contribution is based on the identification of a set of requirements needed being able to model and analyse each of the STS elements. Some of these requirements were met by existing modelling techniques, others were reachable by extending and refining existing ones. This thesis proposes an approach which integrates 3 modelling techniques: FRAM (focused on organisational functions), HAMSTERS (centred on human goals and activities) and ICO (dedicated to the modelling of interactive systems). The principles of the multi-models approach is illustrated on an example for carefully showing the extensions proposed to the selected modelling techniques and how they integrate together. A more complex case study from the ATM World is then presented to demonstrate the scalability of the approach. This case study, dealing with aircraft route change due to bad weather conditions, highlights the ability of the integration of models to cope with performance variability of the various parts of the ST

Hybrid High-Level Nets

This paper presents a new methodology for modeling and simulation of hybrid systems which is called Hybrid High-level Nets (HYNETs). The new methodology integrates three established modeling approaches into one language. High-level Petri Nets represent the basic discrete framework, differential algebraic equations (DAEs) are used to describe continuous systems behavior and object-oriented concepts improve the expressiveness and compactness of models. The paper explains basic ideas of the language and illustrates its usefulness with a small example. 1 INTRODUCTION Modeling and simulation of hybrid systems, i. e. systems consisting of a mixture of discrete and continuous components, is a research area that becomes more and more interesting. This is due to the fact that most systems of real world applications are not purely discrete nor purely continuous and often both parts influence each other. Consider for instance the small example in Figure 1: A level of liquid in a tank changes co..