Discrete Event Command and Control for Formation Flying of Distributed Small Spacecraft Systems

A distributed, multi-vehicle concept for future space missions has been conceived as a solution to the problem of advancing space-based operations within budgetary constraints. Broadly named formation flying, this approach to designing distributed systems across multiple, spatially disbursed platforms is enabled by collectively coordinating a fleet of autonomous spacecraft to function as a unified system. Formation flying offers potential advantages of improved robustness, capability, and cost relative to complicated, single platform systems by using multiple, often small, spacecraft to perform complex multi-sensor tasks. A necessary element in the realization of formation flying systems is the development of methods and technologies that facilitate the transition from treating a distributed spacecraft system as individual elements, to viewing a formation as a coordinated system unified by common objectives. This paper describes the results of research performed to identify fundamental issues that affect the development of command and control (C2) methods applicable to coordinating distributed small spacecraft systems. A discrete event method of distributed command and control is described that is particularly well suited to small spacecraft formation flying. Utilized in many complex terrestrial systems, discrete event systems (DES) concepts facilitate coordination of distributed systems at multiple levels of resolution in an efficient manner. DES also provide a means to integrate intelligent planning and processing operations while interfacing with more traditional subsystem controllers. The basic principals and applicability of DES are described within the context of formation flying and example distributed spacecraft C2 operations are defined

Model-connected safety cases

Regulatory authorities require justification that safety-critical systems exhibit acceptable levels of safety. Safety cases are traditionally documents which allow the exchange of information between stakeholders and communicate the rationale of how safety is achieved via a clear, convincing and comprehensive argument and its supporting evidence. In the automotive and aviation industries, safety cases have a critical role in the certification process and their maintenance is required throughout a system’s lifecycle. Safety-case-based certification is typically handled manually and the increase in scale and complexity of modern systems renders it impractical and error prone.Several contemporary safety standards have adopted a safety-related framework that revolves around a concept of generic safety requirements, known as Safety Integrity Levels (SILs). Following these guidelines, safety can be justified through satisfaction of SILs. Careful examination of these standards suggests that despite the noticeable differences, there are converging aspects. This thesis elicits the common elements found in safety standards and defines a pattern for the development of safety cases for cross-sector application. It also establishes a metamodel that connects parts of the safety case with the target system architecture and model-based safety analysis methods. This enables the semi- automatic construction and maintenance of safety arguments that help mitigate problems related to manual approaches. Specifically, the proposed metamodel incorporates system modelling, failure information, model-based safety analysis and optimisation techniques to allocate requirements in the form of SILs. The system architecture and the allocated requirements along with a user-defined safety argument pattern, which describes the target argument structure, enable the instantiation algorithm to automatically generate the corresponding safety argument. The idea behind model-connected safety cases stemmed from a critical literature review on safety standards and practices related to safety cases. The thesis presents the method, and implemented framework, in detail and showcases the different phases and outcomes via a simple example. It then applies the method on a case study based on the Boeing 787’s brake system and evaluates the resulting argument against certain criteria, such as scalability. Finally, contributions compared to traditional approaches are laid out

Coordination Of Hierarchical Command And Control Services

The purpose of this program is to show emerging information technologies can significantly improve key areas of tactical operations, resulting in the conversion of software developed under the ATO to existing battlefield systems. One such key area is Information Dissemination and Management (ID&M). The key software that will be developed under the ID&M portion requires a collection of agent-based software services that will collaborate during tactical mission planning and execution

Methods and algorithms for integrated multi-scale optimisation of production planning and scheduling

Imperial Users onl

New Fundamental Technologies in Data Mining

The progress of data mining technology and large public popularity establish a need for a comprehensive text on the subject. The series of books entitled by "Data Mining" address the need by presenting in-depth description of novel mining algorithms and many useful applications. In addition to understanding each section deeply, the two books present useful hints and strategies to solving problems in the following chapters. The contributing authors have highlighted many future research directions that will foster multi-disciplinary collaborations and hence will lead to significant development in the field of data mining

Safety Analysis Concept and Methodology for EDDI development (Initial Version)

Executive Summary:This deliverable describes the proposed safety analysis concept and accompanying methodology to be defined in the SESAME project. Three overarching challenges to the development of safe and secure multi-robot systems are identified — complexity, intelligence, and autonomy — and in each case, we review state-of-the-art techniques that can be used to address them and explain how we intend to integrate them as part of the key SESAME safety and security concept, the EDDI.The challenge of complexity is largely addressed by means of compositional model-based safety analysis techniques that can break down the complexity into more manageable parts. This applies both to scale — modelling systems hierarchically and embedding local failure logic at the component-level — and to tasks, where different safety-related tasks (including not just analysis but also requirements allocation and assurance case generation) can be handled by the same set of models. All of this can be combined with the existing DDI concept to create models — EDDIs — that store all of the necessary information to support a gamut of design-time safety processes.Against the challenge of intelligence, we propose a trio of techniques: SafeML and Uncertainty Wrappers for estimating the confidence of a given classification, which can be used as a form of reliability measure, and SMILE for explainability purposes. By enabling us to measure and explain the reliability of ML decision making, we can integrate ML behaviour as part of a wider system safety model, e.g. as one input into a fault tree or Bayesian network. In addition to providing valuable feedback during training, testing, and verification, this allows the EDDI to perform runtime safety monitoring of ML components.The EDDI itself is therefore our primary solution to the twin challenges of autonomy and openness. Using the ConSert approach as a foundation, EDDIs can be made to operate cooperatively as part of a distributed system, issuing and receiving guarantees on the basis of their internal executable safety models to collectively achieve tasks in a safe and secure manner. Finally, a simple methodology is defined to show how the relevant techniques can be applied as part of the EDDI concept throughout the safety development lifecycle

PROCESS-ORIENTED KNOWLEDGE DISCOVERY TO SUPPORT PRODUCT DESIGN USING TEXT MINING

Ph.DDOCTOR OF PHILOSOPH