191 research outputs found

    Category Theory for Autonomous Robots: The Marathon 2 Use Case

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    Model-based systems engineering (MBSE) is a methodology that exploits system representation during the entire system life-cycle. The use of formal models has gained momentum in robotics engineering over the past few years. Models play a crucial role in robot design; they serve as the basis for achieving holistic properties, such as functional reliability or adaptive resilience, and facilitate the automated production of modules. We propose the use of formal conceptualizations beyond the engineering phase, providing accurate models that can be leveraged at runtime. This paper explores the use of Category Theory, a mathematical framework for describing abstractions, as a formal language to produce such robot models. To showcase its practical application, we present a concrete example based on the Marathon 2 experiment. Here, we illustrate the potential of formalizing systems -- including their recovery mechanisms -- which allows engineers to design more trustworthy autonomous robots. This, in turn, enhances their dependability and performance

    Which attacks lead to hazards? Combining safety and security analysis for cyber-physical systems

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    Cyber-Physical Systems (CPS) are exposed to a plethora of attacks and their attack surface is only increasing. However, whilst many attack paths are possible, only some can threaten the system's safety and potentially lead to loss of life. Identifying them is of essence. We propose a methodology and develop a tool-chain to systematically analyse and enumerate the attacks leading to safety violations. This is achieved by lazily combining threat modelling and safety analysis with formal verification and with attack graph analysis. We also identify the minimum sets of privileges that must be protected to preserve safety. We demonstrate the effectiveness of our methodology to discover threat scenarios by applying it to a Communication Based Train Control System. Our design choices emphasise compatibility with existing safety and security frameworks, whilst remaining agnostic to specific tools or attack graphs representations

    Synthesizing FDIR Recovery Strategies for Space Systems

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    Dynamic Fault Trees (DFTs) are powerful tools to drive the design of fault tolerant systems. However, semantic pitfalls limit their practical utility for interconnected systems that require complex recovery strategies to maximize their reliability. This thesis discusses the shortcomings of DFTs in the context of analyzing Fault Detection, Isolation and Recovery (FDIR) concepts with a particular focus on the needs of space systems. To tackle these shortcomings, we introduce an inherently non-deterministic model for DFTs. Deterministic recovery strategies are synthesized by transforming these non-deterministic DFTs into Markov automata that represent all possible choices between recovery actions. From the corresponding scheduler, optimized to maximize a given RAMS (Reliability, Availability, Maintainability and Safety) metric, an optimal recovery strategy can then be derived and represented by a model we call recovery automaton. We discuss dedicated techniques for reducing the state space of this recovery automaton and analyze their soundness and completeness. Moreover, modularized approaches to handle the complexity added by the state-based transformation approach are discussed. Furthermore, we consider the non-deterministic approach in a partially observable setting and propose an approach to lift the model for the fully observable case. We give an implementation of our approach within the Model-Based Systems Engineering (MBSE) framework Virtual Satellite. Finally, the implementation is evaluated based on the FFORT benchmark. The results show that basic non-deterministic DFTs generally scale well. However, we also found that semantically enriched non-deterministic DFTs employing repair or delayed observability mechanisms pose a challenge

    Verification of RoboChart Models with Neural Network Components

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    Current software engineering frameworks for robotics treat artificial neural networks (ANNs) components as black boxes, and existing white-box techniques consider either component-level properties, or properties involving a specific case study. A method to establish properties that may depend on all components in such a system is, as yet, undefined. Our work consists of defining such a method. First, we developed a component whose behaviour is defined by an ANN and acts as a robotic controller. Considering our application to robotics, we focus on pre-trained ANNs used for control. We define our component in the context of RoboChart, where we define modelling notation involving a meta-model and well-formedness conditions, and a process-algebraic semantics. To further support our framework, we defined an implementation of these semantics in Java and CSPM, to enable validation and discretised verification. Given these components, we then developed an approach to verify software systems involving our ANN components. This approach involves replacing existing memoryless, cyclic, controller components with ANN components, and proving that the new system does not deviate in behaviour by more than a constant ε from the original system. Moreover, we describe a strategy for automating these proofs based on Isabelle and Marabou, combining ANN-specific verification tools with general verification tools. We demonstrate our framework using a case study involving a Segway robot where we replace a PID controller with an ANN component. Our contributions can be summarised as follows: we have generated a framework that enables the modelling, validation, and verification of robotic software involving neural network components. Finally, this work represents progress towards establishing the safety and reliability of autonomous robotics

    Simple Framework for Efficient Development of the Functional Requirement Verification-specific Language

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    Докторска теза анализира предлог за имплементацију верификације функционалних програмских захтева. Предмет истраживања је проналажење свих релевантних стандарда, препорука и најбољих пракси, а затим особина и функционалности прате дате стандарде и препоруке у области верификације. Истраживање потом проналази постојећа релевантна решења и њихову усклађеност са датим особинама и функционалностима. Резултат истраживања је развој доменски-специфичног језика за верификацију функсионалних програмских захтјева који имплементира све особине и функционалности чиме потврђује исправност концепта.Doktorska teza analizira predlog za implementaciju verifikacije funkcionalnih programskih zahteva. Predmet istraživanja je pronalaženje svih relevantnih standarda, preporuka i najboljih praksi, a zatim osobina i funkcionalnosti prate date standarde i preporuke u oblasti verifikacije. Istraživanje potom pronalazi postojeća relevantna rešenja i njihovu usklađenost sa datim osobinama i funkcionalnostima. Rezultat istraživanja je razvoj domenski-specifičnog jezika za verifikaciju funksionalnih programskih zahtjeva koji implementira sve osobine i funkcionalnosti čime potvrđuje ispravnost koncepta.The doctoral thesis analyzes the proposal for implementing the verification of functional software requirements. The subject of the research is to find all relevant standards, recommendations, and best practices, and then to examine the features and functionalities that follow the given standards and recommendations in the field of verification. The research then identifies existing relevant solutions and their compatibility with the given features and functionalities. The result of the research is the development of a domain-specific programming language for the verification of functional requitements that implements all the features and functionalities, thus confirming the correctness of the concept

    Volume II Acquisition Research Creating Synergy for Informed Change, Thursday 19th Annual Acquisition Research Proceedings

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    Delhi's Education Revolution

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    In 2015, the Aam Aadmi Party (AAP) was elected to govern Delhi promising to improve public services, including education through government schools that would be the equal of private-school provision. Media reports, along with the party’s re-election in 2020, suggest strong public confidence that AAP are delivering on that promise. But is this success reflected by experience in schools? Delhi’s Education Revolution offers a critical evaluation of the AAP’s education reforms by exploring policy and practice through the eyes of one key group: the government-school teachers tasked with making the AAP’s pledge a reality. Drawing on 110 research interviews conducted via Zoom during the Covid pandemic in the summer of 2020, teachers explain how the reforms have changed their profession and practice, and whether education really has improved for children of all backgrounds. Analysis of views about critical issues such as inclusion and the pressure of achievement targets in classrooms that often contain more than 50 students, informs their observations about the reform programme itself. The study paints a more qualified picture of success than suggested elsewhere and makes a valuable contribution to the understanding of education reforms in India, and most especially, in Delhi

    Delhi's Education Revolution: Teachers, agency & inclusion

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    In 2015, the Aam Aadmi Party (AAP) was elected to govern Delhi promising to improve public services, including education through government schools that would be the equal of private-school provision. Media reports, along with the party’s re-election in 2020, suggest strong public confidence that AAP are delivering on that promise. But is this success reflected by experience in schools? Delhi’s Education Revolution offers a critical evaluation of the AAP’s education reforms by exploring policy and practice through the eyes of one key group: the government-school teachers tasked with making the AAP’s pledge a reality. Drawing on 110 research interviews conducted via Zoom during the Covid pandemic in the summer of 2020, teachers explain how the reforms have changed their profession and practice, and whether education really has improved for children of all backgrounds. Analysis of views about critical issues such as inclusion and the pressure of achievement targets in classrooms that often contain more than 50 students, informs their observations about the reform programme itself. The study paints a more qualified picture of success than suggested elsewhere and makes a valuable contribution to the understanding of education reforms in India, and most especially, in Delhi
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