Verification of Cyberphysical Systems

Abstract

<jats:p>The value of verification of cyberphysical systems depends on the relationship between the state of the software and the state of the physical system. This relationship can be complex because of the real-time nature and different timelines of the physical plant, the sensors and actuators, and the software that is almost always concurrent and distributed. In this paper, we study different ways to construct a transition system model for the distributed and concurrent software components of a CPS. The purpose of the transition system model is to enable model checking, an established and widely used verification technique. We describe a logical-time-based transition system model, which is commonly used for verifying programs written in synchronous languages, and derive the conditions under which such a model faithfully reflects physical states. When these conditions are not met (a common situation), a finer-grained event-based transition system model may be required. We propose an approach for formal verification of cyberphysical systems using Lingua Franca, a language designed for programming cyberphysical systems, and Rebeca, an actor-based language designed for model checking distributed event-driven systems. We focus on the cyber part and model a faithful interface to the physical part. Our method relies on the assumption that the alignment of different timelines during the execution of the system is the responsibility of the underlying platforms. We make those assumptions explicit and clear.</jats:p>

Towards a Verification-Driven Iterative Development of Software for Safety-Critical Cyber-Physical Systems

“…Finally, using the state and sequence diagrams we build Rebeca codes. The final step of this process is mapping Rebeca codes to executable code; in [12] one possible mapping which is building the executable code in Lingua Franca is explained.…”

“…Timed Rebeca [9][10][11] is designed for modeling and formal verification of distributed, concurrent and event-driven asynchronous systems with timing constraints. Timed Rebeca is proposed for verification of cyber-physical systems in [12] and is used for modeling and analysing different CPS examples like medical devices [13] and PLCs [14]. Moreover, Rebeca has a textual syntax closer to the target languages for implementation, like C, C++, or Java, which makes Rebeca usable by engineers used to those programming languages without any additional effort [15][16][17].…”

Visualisation of Control Software for Cyber-Physical Systems

“…Finally, we remark that, though in this paper we focus on controllers visualisation, our methodology can be extended to formal verification of cyber-physical systems [13][14][15], as formal verification and control synthesis are intertwined research areas. Namely, the following is a (non-complete) list of possible envisaged extensions of our approach.…”

“…Namely, a multi-input buck DC-DC converter is a cyberphysical control system where the plant is a mixed-mode analog circuit converting the DC input voltage (V i in Figure 3) to a desired DC output voltage (v O in Figure 3), and the controller computes actions to actuate some circuit switches in order to maintain current and voltage within given bounds. As an example, buck DC-DC converters are used off-chip to scale down the typical laptop battery voltage (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24) to the just few volts needed by the laptop processor (e.g., [71]) as well as on-chip to support Dynamic Voltage and Frequency Scaling (DVFS) in multicore processors (e.g., [72]). Because of its widespread use, control schemas for buck DC-DC converters have been widely studied (e.g., see [71,72]).…”

Operads for complex system design specification, analysis and synthesis

“…This power to unify and express becomes especially important when reasoning across domains with largely independent modelling histories; compare, e.g. [4] ( §2b, d, 3, 4a, 5).…”