Technical Report on Formalisation of the Heart using Analysis of Conduction Time and Velocity of the Electrocardiography and Cellular-Automata

Formal methods based tools and techniques have been recognised to be a promising approach to support the process of verification and validation of a critical system in early stage of the development. Specially, medical devices are very prone to show an unexpected behavior of the system in operating due to stochastic nature of the system and when a system uses traditional methods for system testing. Device-related problems are responsible for a large number of serious injuries. FDA officials has found that many deaths and injuries related to the devices are caused by product design and engineering flaws. Cardiac pacemaker and implantable cardioverter-defibrillators (ICDs) are main critical medical devices, which require close-loop modeling (integration of system and environment modeling) for verification purpose to obtain a certificate from certification bodies. No any technique is available to provide an environment modeling to verify the developed system model. This report presents a methodology to model a biological system, like heart, for modeling a biological environment. The heart model is mainly based on electrocardiography analysis, which models the heart system at cellular level. Main objective of this methodology is to model the heart system and integrate with medical device model like cardiac pacemaker to specify a close-loop model. Close-loop model of an environment and a device is an open problem in real world. Industries are striving for such kind of approach from long time to validate a system model under a virtual biological environment. Our approach involves the pragmatic combination of formal specification of a system and a biological environment to model a close-loop system to verify the correctness of a system and helps in quality improvement of the system

Analyzing Requirements Using Environment Modelling

Analysing requirements is a major challenge in the area of safety-critical software, where requirements quality is an important issue to build a dependable critical system. Most of the time, any project fails due to lack of understanding of user needs, missing functional and non-functional system requirements, inadequate methods and tools, and inconsistent system specification. This often results from the poor quality of system requirements. Based on our experience and knowledge, an environment model has been recognized to be a promising approach to support requirements engineering to validate a system specification. It is crucial to get an approval and feedback in early stage of system development to ensure completeness and correctness of requirements specification. In this paper, we propose a method for analysing system requirements using a closed-loop modelling technique. A closed-loop model is an integration of system model and environment model, where both the system and environment models are formalized using formal techniques. Formal verification of the closed-loop model helps to identify missing system requirements or new emergent behaviours, which are not covered earlier during the requirements elicitation process. Moreover, an environment model assists in the construction, clarification, and validation of the given system requirements

From Verified Models to Verified Code for Safe Medical Devices

Medical devices play an essential role in the care of patients around the world, and can have a life-saving effect. An emerging category of autonomous medical devices like implantable pacemakers and implantable cardioverter defibrillators (ICD) diagnose conditions of the patient and autonomously deliver therapies. Without trained professionals in the loop, the software component of autonomous medical devices is responsible for making critical therapeutic decisions, which pose a new set of challenges to guarantee patient safety. As regulation effort to guarantee patient safety, device manufacturers are required to submit evidence for the safety and efficacy of the medical devices before they can be released to the market. Due to the closed-loop interaction between the device and the patient, the safety and efficacy of autonomous medical devices must ultimately be evaluated within their physiological context. Currently the primary closed-loop validation of medical devices is in form of clinical trials, in which the devices are evaluated on real patients. Clinical trials are expensive and expose the patients to risks associated with untested devices. Clinical trials are also conducted after device development, therefore issues found during clinical trials are expensive to fix. There is urgent need for closed-loop validation of autonomous medical devices before the devices are used in clinical trials. In this thesis, I used implantable cardiac devices to demonstrate the applications of model-based approaches during and after device development to provide confidence towards the safety and efficacy of the devices. A heart model structure is developed to mimic the electrical behaviors of the heart in various heart conditions. The heart models created with the model structure are capable of interacting with implantable cardiac devices in closed-loop and can provide physiological interpretations for a large variety of heart conditions. With the heart models, I demonstrated that closed-loop model checking is capable of identifying known and unknown safety violations within the pacemaker design. More importantly, I developed a framework to choose the most appropriate heart models to cover physiological conditions that the pacemaker may encounter, and provide physiological context to counter-examples returned by the model checker. A model translation tool UPP2SF is then developed to translate the pacemaker design in UPPAAL to Stateflow, and automatically generated to C code. The automated and rigorous translation ensures that the properties verified during model checking still hold in the implementation, which justifies the model checking effort. Finally, the devices are evaluated with a virtual patient cohort consists of a large number of heart models before evaluated in clinical trials. These in-silico pre-clinical trials provide useful insights which can be used to increase the success rate of a clinical trial. The work in this dissertation demonstrated the importance and challenges to represent physiological behaviors during closed-loop validation of autonomous medical devices, and demonstrated the capability of model-based approaches to provide safety and efficacy evidence during and after device development

Modelling bio-compatible and bio-integrative medical devices

International audienceDeveloping and producing medical devices and healthcare systems is a crucial issue, both for the economy and for providing safe advances in healthcare delivery. We propose a taxonomy of medical human machine systems and we define classes of healthcare applications for identifying a number of approaches and to overcome difficulties of bio-compatibility and bio-integration. Our aim is to demonstrate how medical devices design, and more generally human-machine system concepts and epistemology, depend on our skills to think and conceptualize generally human system integration. We claim that it is necessary to reclaim these concepts for ensuring correct by construction medical devices bio-compatibility and biointegrative properties from the early stage of the design process

Formalizing the Cardiac Pacemaker Resynchronization Therapy

For many years, formal methods have been used to design and develop critical systems in order to guarantee safety and security and the correctness of desired behaviours, through formal verification and validation techniques and tools. The development of high confidence medical devices such as the cardiac pacemaker, is one of the grand challenges in the area of verified software that need formal reasoning and proof-based development. This paper presents an example of how we used previous experience in developing a cardiac pacemaker using Event-B, to build an incremental proof-based development of a new pacemaker that uses Cardiac Resynchronization Therapy (CRT), also known as biventricular pacing or multisite pacing. In this work, we formalized the required behaviours of CRT including timing constraints and safety properties. We formalized the system using Event-B, and made use of the included Rodin tools to check the internal consistency with respect to safety properties, invariants and events. The system behaviours of the proven model were validated through the use of the ProB model checker

Considerations in designing a cybernetic simple 'learning' model; and an overview of the problem of modelling learning

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Learning is viewed as a central feature of living systems and must be manifested in any artifact that claims to exhibit general intelligence. The central aims of the thesis are twofold: (1) - To review and critically assess the empirical and theoretical aspects of learning as have been addressed in a multitude of disciplines, with the aim of extracting fundamental features and elements. (2) - To develop a more systematic approach to the cybernetic modelling of learning than has been achieved hitherto. In pursuit of aim (1) above the following discussions are included: Historical and Philosophical backgrounds; Natural learning, both physiological and psychological aspects; Hierarchies of learning identified in the evolutionary, functional and developmental senses; An extensive section on the general problem of modelling of learning and the formal tools, is included as a link between aims (1) and (2). Following this a systematic and historically oriented study of cybernetic and other related approaches to the problem of modelling of learning is presented. This then leads to the development of a state-of-the-art general purpose experimental cybernetic learning model. The programming and use of this model is also fully described, including an elaborate scheme for the manifestation of simple learning

Aerospace medicine and biology: A cumulative index to the continuing bibliography of the 1973 issues

A cumulative index to the abstracts contained in Supplements 112 through 123 of Aerospace Medicine and Biology A Continuing Bibliography is presented. It includes three indexes: subject, personal author, and corporate source

Computations and Computers in the Sciences of Mind and Brain

Computationalism says that brains are computing mechanisms, that is, mechanisms that perform computations. At present, there is no consensus on how to formulate computationalism precisely or adjudicate the dispute between computationalism and its foes, or between different versions of computationalism. An important reason for the current impasse is the lack of a satisfactory philosophical account of computing mechanisms. The main goal of this dissertation is to offer such an account. I also believe that the history of computationalism sheds light on the current debate. By tracing different versions of computationalism to their common historical origin, we can see how the current divisions originated and understand their motivation. Reconstructing debates over computationalism in the context of their own intellectual history can contribute to philosophical progress on the relation between brains and computing mechanisms and help determine how brains and computing mechanisms are alike, and how they differ. Accordingly, my dissertation is divided into a historical part, which traces the early history of computationalism up to 1946, and a philosophical part, which offers an account of computing mechanisms. The two main ideas developed in this dissertation are that (1) computational states are to be identified functionally not semantically, and (2) computing mechanisms are to be studied by functional analysis. The resulting account of computing mechanism, which I call the functional account of computing mechanisms, can be used to identify computing mechanisms and the functions they compute. I use the functional account of computing mechanisms to taxonomize computing mechanisms based on their different computing power, and I use this taxonomy of computing mechanisms to taxonomize different versions of computationalism based on the functional properties that they ascribe to brains. By doing so, I begin to tease out empirically testable statements about the functional organization of the brain that different versions of computationalism are committed to. I submit that when computationalism is reformulated in the more explicit and precise way I propose, the disputes about computationalism can be adjudicated on the grounds of empirical evidence from neuroscience

Aerospace Medicine and Biology: A cumulative index to the 1974 issues of a continuing bibliography

This publication is a cumulative index to the abstracts contained in supplements 125 through 136 of Aerospace Medicine and Biology: A Continuing Bibliography. It includes three indexes--subject, personal author, and corporate source

Wired Bodies. New Perspectives on the Machine-Organism Analogy

The machine-organism analogy has played a pivotal role in the history of Western philosophy and science. Notwithstanding its apparent simplicity, it hides complex epistemological issues about the status of both organism and machine and the nature of their interaction. What is the real object of this analogy: organisms as a whole, their parts or, rather, bodily functions? How can the machine serve as a model for interpreting biological phenomena, cognitive processes, or more broadly the social and cultural transformations of the relations between individuals, and between individuals and the environments in which they live. Wired bodies. New perspectives on the machine-organism analogy provides the reader with some of the latest perspectives on this vast debate, addressing three major topics: 1) the development of a ‘mechanistic’ framework in medicine and biology; 2) the methodological issues underlying the use of ‘simulation’ in cognitive science; 3) the interaction between humans and machines according to 20th century epistemology