Synthesizing SystemC Code from Delay Hybrid CSP

Delay is omnipresent in modern control systems, which can prompt oscillations and may cause deterioration of control performance, invalidate both stability and safety properties. This implies that safety or stability certificates obtained on idealized, delay-free models of systems prone to delayed coupling may be erratic, and further the incorrectness of the executable code generated from these models. However, automated methods for system verification and code generation that ought to address models of system dynamics reflecting delays have not been paid enough attention yet in the computer science community. In our previous work, on one hand, we investigated the verification of delay dynamical and hybrid systems; on the other hand, we also addressed how to synthesize SystemC code from a verified hybrid system modelled by Hybrid CSP (HCSP) without delay. In this paper, we give a first attempt to synthesize SystemC code from a verified delay hybrid system modelled by Delay HCSP (dHCSP), which is an extension of HCSP by replacing ordinary differential equations (ODEs) with delay differential equations (DDEs). We implement a tool to support the automatic translation from dHCSP to SystemC

A Refinement Strategy for Hybrid System Design with Safety Constraints

Whenever continuous dynamics and discrete control interact, hybrid systems arise. As hybrid systems become ubiquitous and more and more complex, analysis and synthesis techniques are in high demand to design safe hybrid systems. This is however challenging due to the nature of hybrid systems and their designs, and the question of how to formulate and reason their safety problems. Previous work has demonstrated how to extend discrete modelling language Event-B with continuous supports to integrate traditional refinement in hybrid system design. In the same spirit, we extend previous work by proposing a strategy that can coherently refine an abstract hybrid system design with safety constraints down to the concrete one with implementable discrete control that can behave safely. Our proposal is validated on the design of a smart heating system, and we share with our experience

Automated verification of reactive and concurrent programs by calculation

Reactive programs combine traditional sequential programming constructs with primitives to allow communication with other concurrent agents. They are ubiquitous in modern applications, ranging from components systems and web services, to cyber-physical systems and autonomous robots. In this paper, we present an algebraic verification strategy for concurrent reactive programs, with a large or infinite state space. We define novel operators to characterise interactions and state updates, and an associated equational theory. With this we can calculate a reactive program's denotational semantics, and thereby facilitate automated proof. Of note is our reasoning support for iterative programs with reactive invariants, based on Kleene algebra, and for parallel composition. We illustrate our strategy by verifying a reactive buffer. Our laws and strategy are mechanised in Isabelle/UTP, our implementation of Hoare and He's Unifying Theories of Programming (UTP) framework, to provide soundness guarantees and practical verification support

Model-based re-engineering of control application : Code generation and verification

This thesis introduces a way to transform from traditional software development to model-based design in the control application domain, specifically PLC-based control systems. Traditional software development refers to a process where code is written directly based on system and module design after system requirements are defined. Model-based re-engineering refers to a process where old software is converted to new implementation using a model-based design methodology. Model-based design is a mathematical and visual method to address complex control system problems and is focused on the design phase of the development process. There are multiple reasons why there is a rising interest to use model-based design instead of traditional development but changing to this development model is problematic. The old codebase is usually done by handwritten code and transforming to model-based and new platforms can be complex. This thesis answers the presented problem by developing a systematic way how this transformation can be done. This is achieved by combining re-engineering with V-model. Furthermore, a case study is performed which uses the introduced process for transforming the reference code into a new implementation using model-based design. This case study focuses on how the verification process evolves when re-engineering is part of the V-model. This case study is completed using proprietary software for the model-based design process known as MathWorks’ Simulink and Simulink PLC-coder. Case study showed that it was possible to create a redesigned software using introduced re-engineering model. As a result of this case study, problems in the re-engineering process and the case study itself are explored and an idea for further study is presented

Language evolution and healthiness for critical cyber‐physical systems

From Wiley via Jisc Publications RouterHistory: received 2020-04-13, rev-recd 2020-05-13, accepted 2020-06-25, pub-electronic 2020-09-16, pub-print 2021-09Article version: VoRPublication status: PublishedFunder: National Natural Science Foundation of China; Id: http://dx.doi.org/10.13039/501100001809; Grant(s): 61872145Funder: National Key Research and Development Program of China; Id: http://dx.doi.org/10.13039/501100012166; Grant(s): 2018YFB2101300Funder: Shanghai Collaborative Innovation Center of Trustworthy Software for Internet of Things; Grant(s): ZF1213Abstract: In the effort to develop critical cyber‐physical systems, it is tempting to extend existing computing formalisms to include continuous behaviour. This may happen in a way that neglects elements necessary for correctly expressing continuous properties of the mathematics and correct physical properties of the real‐world physical system. A simple language is taken to illustrate these possibilities. Issues and risks latent in this kind of approach are identified and discussed under the umbrella of ‘healthiness conditions’. Modifications to the language in the light of the conditions discussed are elaborated, resulting in the language Combined Discrete and Physical Programmes in Parallel (CDPPP). An example air conditioning system is used to illustrate the concepts presented, and it is developed both in the original ‘unhealthy’ language and in the modified ‘healthier’ CDPPP. The formal semantics of the improved language is explored

Formal verification of Simulink/Stateflow diagrams: a deductive approach

This book presents a state-of-the-art technique for formal verification of continuous-time Simulink/Stateflow diagrams, featuring an expressive hybrid system modelling language, a powerful specification logic and deduction-based verification approach, and some impressive, realistic case studies. Readers will learn the HCSP/HHL-based deductive method and the use of corresponding tools for formal verification of Simulink/Stateflow diagrams. They will also gain some basic ideas about fundamental elements of formal methods such as formal syntax and semantics, and especially the common techniques applied in formal modelling and verification of hybrid systems. By investigating the successful case studies, readers will realize how to apply the pure theory and techniques to real applications, and hopefully will be inspired to start to use the proposed approach, or even develop their own formal methods in their future work

Formal Verification of Simulink/Stateflow Diagrams [electronic resource] : A Deductive Approach /

This book presents a state-of-the-art technique for formal verification of continuous-time Simulink/Stateflow diagrams, featuring an expressive hybrid system modelling language, a powerful specification logic and deduction-based verification approach, and some impressive, realistic case studies. Readers will learn the HCSP/HHL-based deductive method and the use of corresponding tools for formal verification of Simulink/Stateflow diagrams. They will also gain some basic ideas about fundamental elements of formal methods such as formal syntax and semantics, and especially the common techniques applied in formal modelling and verification of hybrid systems. By investigating the successful case studies, readers will realize how to apply the pure theory and techniques to real applications, and hopefully will be inspired to start to use the proposed approach, or even develop their own formal methods in their future work.1 Introduction -- 2 Preliminaries -- 3 Unifying Theories of Programming -- 4 Simulink -- 5 Stateflow and Its Combination with Simulink -- 6 Hybrid CSP -- 7 Hybrid Hoare Logic -- 8 The HHL Prover -- 9 Invariant Generation -- 10 Translating Simulink Diagrams into HCSP -- 11 Translating Simulink/Stateflow Diagrams into HCSP -- 12 From HCSP to Simulink -- 13 MARS A Toolkit for Modelling, Analysis and Verification of Hybrid Systems -- 14 Case Studies.This book presents a state-of-the-art technique for formal verification of continuous-time Simulink/Stateflow diagrams, featuring an expressive hybrid system modelling language, a powerful specification logic and deduction-based verification approach, and some impressive, realistic case studies. Readers will learn the HCSP/HHL-based deductive method and the use of corresponding tools for formal verification of Simulink/Stateflow diagrams. They will also gain some basic ideas about fundamental elements of formal methods such as formal syntax and semantics, and especially the common techniques applied in formal modelling and verification of hybrid systems. By investigating the successful case studies, readers will realize how to apply the pure theory and techniques to real applications, and hopefully will be inspired to start to use the proposed approach, or even develop their own formal methods in their future work