Assume-guarantee contracts for continuous-time systems

Saoud, Adnane; Girard, Antoine; Fribourg, Laurent

doi:10.1016/j.automatica.2021.109910

Cited by 32 publications

(24 citation statements)

References 34 publications

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“…Different compositional approaches have been proposed in the literature to overcome this challenge in dealing with large-scale CPS. The two most commonly used schemes are based on: 1) assume-guarantee contracts [92,173,181] which are originally introduced in the computer science literature and 2) the input-output properties of the system, including those expressed as small-gain [160,92,148] or dissipativity properties [229,187] which are originally introduced in the control theory literature. Here, the overall large-scale systems are usually seen as interconnections of smaller (reasonably sized) components, i.e., subsystems.…”

Section: Compositional Reasoning For Scalabilitymentioning

confidence: 99%

Secure-by-Construction Synthesis of Cyber-Physical Systems

Liu¹,

Trivedi²,

Yin³

2022

Preprint

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Correct-by-construction synthesis is a cornerstone of the confluence of formal methods and control theory towards designing safety-critical systems. Instead of following the time-tested, albeit laborious (re)design-verify-validate loop, correct-by-construction methodology advocates the use of continual refinements of formal requirements-connected by chains of formal proofs-to build a system that assures the correctness by design. A remarkable progress has been made in scaling the scope of applicability of correct-byconstruction synthesis-with a focus on cyber-physical systems that tie discrete-event control with continuous environment-to enlarge control systems by combining symbolic approaches with principled state-space reduction techniques. Unfortunately, in the security-critical control systems, the security properties are verified ex post facto the design process in a way that undermines the correct-by-construction paradigm. We posit that, to truly realize the dream of correct-by-construction synthesis for security-critical systems, security considerations must take center-stage with the safety considerations. Moreover, catalyzed by the recent progress on the opacity sub-classes of security properties and the notion of hyperproperties capable of combining security with safety properties, we believe that the time is ripe for the research community to holistically target the challenge of secure-by-construction synthesis. This paper details our vision by highlighting the recent progress and open challenges that may serve as bricks for providing a solid foundation for secure-by-construction synthesis of cyber-physical systems.The revolution in miniaturized communication devices in the beginning of this millennium contributed towards a revolution in the internet-of-things (IoT) and the networked systems woven around them: the cyber-physical systems (CPS). CPS are marked by a close-knit interaction of discrete computation and continuous control over a network and are playing critical roles in virtually every aspect of our modern experience ranging from consumer electronics to implantable medical devices, from smart cars to smart hospitals, and from controlling our power systems to safeguarding our nuclear rectors. These systems are clearly safety-critical as a bug in their design could be life threatening, but given their societal implications, they are also security-critical where a bug in their design may have the potential to jeopardize the privacy, trust, and economic interests of society built around them." We believe that the security considerations should be elevated as primary design drivers along with safety ones to tackle the design challenge of modern CPS and call for a need to expand the correct-byconstruction paradigm of designing safety-critical systems to encompass security: we call this paradigm secure-by-construction. This paper synthesizes ideas from three research communities: discrete event systems (DES), control systems (CS), and formal methods (FM) to pose and study central problems supporting...

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Section: Compositional Reasoning For Scalabilitymentioning

confidence: 99%

Secure-by-Construction Synthesis of Cyber-Physical Systems

Liu¹,

Trivedi²,

Yin³

2022

Preprint

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“…Related work: While AGCs have been extensively used in the computer science community [15], [22], new frameworks of AGCs for dynamical systems with continuous state-variables have been proposed recently in [8], [10] for continuous-time systems, and [7], [23,Chapter 2] for discrete-time systems. In this paper, we follow the same behavioural framework of AGCs for continuous-time systems proposed in [8]. In the following, we provide a comparison with the approach proposed in [8], [10].…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we follow the same behavioural framework of AGCs for continuous-time systems proposed in [8]. In the following, we provide a comparison with the approach proposed in [8], [10]. A detailed comparison between the framework in [8], the one in [7] and existing approaches from the computer science community [15], [22] can be found in [8, Section 1].…”

Section: Introductionmentioning

confidence: 99%

Compositional Synthesis of Signal Temporal Logic Tasks via Assume-Guarantee Contracts

Liu¹,

Saoud²,

Jagtap³

et al. 2022

Preprint

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In this paper, we focus on the problem of compositional synthesis of controllers enforcing signal temporal logic (STL) tasks over a class of continuous-time nonlinear interconnected systems. By leveraging the idea of funnel-based control, we show that a fragment of STL specifications can be formulated as assume-guarantee contracts. A new concept of contract satisfaction is then defined to establish our compositionality result, which allows us to guarantee the satisfaction of a global contract by the interconnected system when all subsystems satisfy their local contracts. Based on this compositional framework, we then design closed-form continuous-time feedback controllers to enforce local contracts over subsystems in a decentralized manner. Finally, we demonstrate the effectiveness of our results on two numerical examples.

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“…An assume/guarantee framework for continuous-time dynamical systems based on the notion of simulation was considered in Besselink et al (2019), in which an algorithm for verifying that a system satisfies a given contract was provided using geometric control theory methods ( Van der Schaft (2004)). Assume/guarantee contracts have also been considered in Saoud et al (2018Saoud et al ( , 2019, in which assumptions are made on the input signals and guarantees are on the state and output signals.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we present a framework for assume/guarantee contracts that prescribes assumptions on the inputs and guarantees on the output, extending the framework of Saoud et al (2018Saoud et al ( , 2019. First, we allow the requirement on the output to depend on the input, which is natural for sensor systems and tasks like tracking.…”

Section: Introductionmentioning

confidence: 99%

Assume/Guarantee Contracts for Dynamical Systems: Theory and Computational Tools

Sharf¹,

Besselink²,

Molin³

et al. 2020

Preprint

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Modern engineering systems include many components of different types and functions. Verifying that these systems satisfy given specifications can be an arduous task, as most formal verification methods are limited to systems of moderate size. Recently, contract theory has been proposed as a modular framework for defining specifications. In this paper, we present a contract theory for discrete-time dynamical control systems relying on assume/guarantee contracts, which prescribe assumptions on the input of the system and guarantees on the output. We then focus on contracts defined by linear constraints, and develop efficient computational tools for verification of satisfaction and refinement based on linear programming. We exemplify these tools in a simulation example, proving safety for a two-vehicle autonomous driving setting.

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Assume-guarantee contracts for continuous-time systems

Cited by 32 publications

References 34 publications

Secure-by-Construction Synthesis of Cyber-Physical Systems

Secure-by-Construction Synthesis of Cyber-Physical Systems

Compositional Synthesis of Signal Temporal Logic Tasks via Assume-Guarantee Contracts

Assume/Guarantee Contracts for Dynamical Systems: Theory and Computational Tools

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