Formal Safety Assessment via Contract-Based Design

Bozzano, Marco; Cimatti, Alessandro; Mattarei, Cristian; Tonetta, Stefano

doi:10.1007/978-3-319-11936-6_7

Cited by 18 publications

(20 citation statements)

References 18 publications

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“…Various model-based dependability analysis methods have been developed, such as HiP-HOPS [26,29], AADL [13] and AltaRica [22], which use FTA as their primary means and automate the synthesis process to some degrees. More recently, the concept of contract-based design has also been used for automatic generation of hierarchical fault trees from formal models [3].…”

Section: Discussion and Related Workmentioning

confidence: 99%

Reasoning with failures

Jahanian,

McIver

2020

Preprint

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Safety Instrumented Systems (SIS) protect major hazard facilities, e.g. power plants, against catastrophic accidents. An SIS consists of hardware components and a controller software -the "program". Current safety analyses of SIS' include the construction of a fault tree, summarising potential faults of the components and how they can arise within an SIS. The exercise of identifying faults typically relies on the experience of the safety engineer. Unfortunately the program part is often too complicated to be analysed in such a "by hand" manner and so the impact it has on the resulting safety analysis is not accurately captured. In this paper we demonstrate how a formal model for faults and failure modes can be used to analyse the impact of an SIS program. We outline the underlying concepts of Failure Mode Reasoning and its application in safety analysis, and we illustrate the ideas on a practical example.

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Section: Discussion and Related Workmentioning

confidence: 99%

Reasoning with failures

Jahanian,

McIver

2020

Preprint

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“…We refer to [23] for a comparison with Altarica/OCAS (carried out using a license courtesy of Dassault Aviation), and to [17] for an exhaustive evaluation of the novel routines implemented in XSAP. As future work, we intend to extend XSAP in several directions. First, we want to incorporate Contract-Based Safety Assessment (CBSA) techniques [47], enabling the generation of hierarchical FTs following the design structure. Moreover, we wish to incorporate the routines for evaluation of reliability architectures we developed in [48].…”

Section: Discussionmentioning

confidence: 99%

The xSAP Safety Analysis Platform

Bittner

Bozzano

Cavada

et al. 2016

Lecture Notes in Computer Science

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Abstract. This paper describes the XSAP safety analysis platform. XSAP provides several model-based safety analysis features for finite-and infinite-state synchronous transition systems. In particular, it supports library-based definition of fault modes, an automatic model extension facility, generation of safety analysis artifacts such as Dynamic Fault Trees (DFTs) and Failure Mode and Effects Analysis (FMEA) tables. Moreover, it supports probabilistic evaluation of Fault Trees, failure propagation analysis using Timed Failure Propagation Graphs (TFPGs), and Common Cause Analysis (CCA). XSAP has been used in several industrial projects as verification back-end, and is currently being evaluated in a joint R&D Project involving FBK and The Boeing Company.

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“…In [BCMT14], the authors present an approach to build hierarchical fault trees following the system structure. The approach has been implemented in a contract-based framework implemented in the ocra platform [ocr21].…”

Section: Fault Tree Analysismentioning

confidence: 99%

Model-based Safety Assessment of a Triple Modular Generator with xSAP

et al. 2021

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The system design process needs to cope with the increasing complexity and size of systems,motivating the replacement of labor intensivemanual techniques with automated and semi-automated approaches.Recently, formal methods techniques, such as model-based verification and safety assessment, have been increasingly used to model systems under fault and to analyze them, generating artifacts such as fault trees and FMEA tables. In this paper, we show how to apply model-based techniques to a realistic case study from the avionics domain: a high integrity power distribution system, the Triple Modular Generator (TMG). The TMG is composed of a redundant and reconfigurable plant and a controller that must guarantee a high level of reliability. The case study is a significant challenge, from the modeling perspective, since it implements a complex reconfiguration policy, specified via a number of requirements in natural language, including a set of mutually dependent and potentially conflicting priority constraints. Moreover, from the verification standpoint, the controller must be able to handle an exponential number of possible faulty configurations. Our contribution is twofold. First, we formalize and validate the requirements and, using a constraint-based modeling style, we synthesize a correct by construction controller, avoiding the enumeration of all possible fault configurations, as is currently done by manual approaches. Second, we describe a comprehensive methodology and process, supported by the xSAP safety analysis platform that targets the modeling and safety assessment of faulty systems. Using xSAP, we are able to automatically extract minimal cut sets for the TMG. We demonstrate the scalability of our approach by analyzing a parametric version of the TMG case study that contains more than 700 variables and 90 faults.

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Formal Safety Assessment via Contract-Based Design

Cited by 18 publications

References 18 publications

Reasoning with failures

Reasoning with failures

The xSAP Safety Analysis Platform

Model-based Safety Assessment of a Triple Modular Generator with xSAP

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