170,381 research outputs found
CISIApro critical infrastructures modeling technique for an effective decision-making support
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Negativizability: A useful property for distributed state estimation and control in Cyber–Physical Systems
No full textIn this paper we focus our attention on an interesting property of linear and time-invariant systems, namely negativizability: a pair (A,C) is negativizable if a gain matrix K exists such that A−KC is negative definite. Notably, in this paper we show that negativizability can be a useful feature for solving distributed estimation and control problems in Cyber–Physical Systems (CPS), since such a property allows a network of agents to bring the estimation error to zero or to control the overall system by designing gains that only require information locally available to each agent. In detail, we first characterize the negativizability problem, developing a necessary and sufficient condition for the problem to admit a solution. Then, we show how distributed estimation and control schemes for linear and time-invariant CPSs can greatly benefit from this property. A simulation campaign aiming at showing the potential of negativizability in the context of distributed state estimation and control of CPSs concludes the paper
Negativizability for Nonlinear Estimation in Cyber-Physical Systems
No full textThis letter introduces a novel fully distributed estimation scheme for nonlinear continuous-time dynamics over directed and strongly connected graphs. Leveraging on the assumption of local negativizability, the proposed approach performs the estimation of the interdependent subsystems of a cyber-physical system, despite the presence of nonlinear dependencies on the dynamics. This transforms the intricate task of nonlinear state estimation by each agent into more manageable local negativizability problems for the design of the estimation gains. A pivotal aspect of the approach is that each agent should be aware of an upper bound on the Lipschitz constant of the overall nonlinear function that characterizes the dynamics. To face this issue, we developed a novel distributed methodology for the estimation of the global Lipschitz constant, starting from the local observations of the system's nonlinearities. The effectiveness of the proposed scheme is numerically demonstrated through simulations
Smart Behavioural Filter for Industrial Internet of Things
No full textWe are currently experiencing the fourth industrial revolution. This is what the German government initiative, first, has identified with ‘Industry 4.0’. The manufacturing future will be marked and will go through the new automation technologies that are being introduced with Industrial Internet of Things (I2oT). Industrial Control Systems (ICSs) are exploiting I2oT for reducing costs and improving efficiency. However, ICSs are already jeopardized by an increasingly large set of threat vectors. Those threats are used by malicious actors to misuse physical Critical Infrastructures that usually are vital services for well-being. I2oT implementation increases the threat surface, generating new possible vulnerabilities. Information Technology (IT) classical approaches to cyber attacks cannot be applied to ICS due to their extreme differences from main priorities to resource constrains. Therefore, innovative approaches and equipment must be developed to suit with ICS world. In this paper, a Smart Behavioural Filter (SBF) for the PLCs (Programmable Logic Controllers) is proposed aiming to secure the PLC itself against logic attacks, that are stealth for other more classical security approaches. An example of the considered logic attacks is many open and close commands towards a valve in a short time. Those logic attacks are usually a sequence of well-formed packets in which the content represents an anomalous and unpredicted behaviour. This smart field equipment can react in short time to cyber attacks isolating the PLC, communicate with other equipment like itself and increasing in general the resilience of the physical system. It can also generate alarms for the local Intrusion Detection System (IDS). The proposed equipment has been developed and validated in a real test-bed within the FP7 CockpitCI project and H2020 ATENA project.Please reference the final version available on the website of the publisher: www.sciencedirect.com/science/article/pii/S187454821730179
Reconstruction of Riser Profiles by an Underwater Robot Using Inertial Navigation
No full textThis paper proposes a kinematic model and an inertial localization system architecture for a riser inspecting robot. The robot scrolls outside the catenary riser, used for underwater petroleum exploration, and is designed to perform several nondestructive tests. It can also be used to reconstruct the riser profile. Here, a realistic simulation model of robot kinematics and its environment is proposed, using different sources of data: oil platform characteristics, riser static configuration, sea currents and waves, vortex-induced vibrations, and instrumentation model. A dynamic finite element model of the riser generates a nominal riser profile. When the robot kinematic model virtually scrolls the simulated riser profile, a robot kinematic pattern is calculated. This pattern feeds error models of a strapdown inertial measurement unit (IMU) and of a depth sensor. A Kalman filter fuses the simulated accelerometers data with simulated external measurements. Along the riser vertical part, the estimated localization error between the simulated nominal and Kalman filter reconstructed robot paths was about 2 m. When the robot model approaches the seabed it assumes a more horizontal trajectory and the localization error increases significantly
La testualità
No full textLe linee guida della linguistica testuale in rapporto alla didattica della lingua italiana
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