Distributed Cyber Physical Systems Research Articles

A Deep Learning-Driven Self-Conscious Distributed Cyber-Physical System for Renewable Energy Communities.

The Internet of Things (IoT) is transforming various domains, including smart energy management, by enabling the integration of complex digital and physical components in distributed cyber-physical systems (DCPSs). The design of DCPSs has so far been focused on performance-related, non-functional requirements. However, with the growing power consumption and computation expenses, sustainability is becoming an important aspect to consider. This has led to the concept of energy-aware DCPSs, which integrate conventional non-functional requirements with additional attributes for sustainability, such as energy consumption. This research activity aimed to investigate and develop energy-aware architectural models and edge/cloud computing technologies to design next-generation, AI-enabled (and, specifically, deep-learning-enhanced), self-conscious IoT-extended DCPSs. Our key contributions include energy-aware edge-to-cloud architectural models and technologies, the orchestration of a (possibly federated) edge-to-cloud infrastructure, abstractions and unified models for distributed heterogeneous virtualized resources, innovative machine learning algorithms for the dynamic reallocation and reconfiguration of energy resources, and the management of energy communities. The proposed solution was validated through case studies on optimizing renewable energy communities (RECs), or energy-aware DCPSs, which are particularly challenging due to their unique requirements and constraints; in more detail, in this work, we aim to define the optimal implementation of an energy-aware DCPS. Moreover, smart grids play a crucial role in developing energy-aware DCPSs, providing a flexible and efficient power system integrating renewable energy sources, microgrids, and other distributed energy resources. The proposed energy-aware DCPSs contribute to the development of smart grids by providing a sustainable, self-consistent, and efficient way to manage energy distribution and consumption. The performance demonstrates our approach's effectiveness for consumption and production (based on RMSE and MAE metrics). Our research supports the transition towards a more sustainable future, where communities adopting REC principles become key players in the energy landscape.

Distributed cyber-physical systems that enhance local-based frugal innovation toward a sustainable built environment

The paper debates the comparison between centralized cyber-physical systems and distributed cyber-physical systems (CPS). Centralized CPS implies a system where a single player standardizes data format and protocol together with core services. Distributed CPS implies a system where varieties of digitalization systems by multiple vendors are interconnected to adapt to specific local contexts. Then the paper identifies that distributed CPS has practical advantages over centralized CPS. However, distributed CPS has potential disadvantages that threaten interconnectivity among digitalization systems by multiple vendors. The paper illustrates how such fragmentation could be avoided; it presents how interoperable linkage among multiple systems is realized. IoT-Hub, a sort of data conversion system, is an enabler of interoperability. The paper illustrates the framework of distributed CPS. That comprises several layers that could be managed autonomously by independent players regardless of activities in other layers. The paper exemplifies local-based frugal innovation by such distributed CPS. One example is IoT-based proactive energy demand control system. The system is composed of sensing systems, component systems and application software. The distributed CSP that deploys IoT-Hub enables adaptable coordination of building elements and digitalized systems respecting local specific contexts. In such a way, distributed CPS provides a comfortable indoor climate with optimized energy use. The other example is IoT-based inventory system for building materials. The system is composed of manufacturing process monitoring systems and logistics monitoring systems. The integrated system could provide reportable and verifiable inventory data of building materials. The system can facilitate responsible use of building materials by providing inventory data that is a piece of essential information for environmental declaration. Exemplified cases suggest how distributed CPS strategy has the potential to encourage a broad range of entrepreneurs to commit to frugal innovation toward a sustainable built environment.

Construction and Analysis of Petri Net Model for Distributed Cyber Physical Systems

A Distributed Cyber-Physical System (DCPS) composition poses challenges in determining its emergent behaviour. These challenges occur due to (1) the appearance of causal loops of information and energy flow through cyber and physical channels and (2) inherent non-determinism in the temporally ordered flow of events within independently evolving interacting processes of Constituent Systems (CSs). Hence, there is a need to construct a model of the envisaged schematic of DCPS composition for analysis and verification of its significant properties in the conceptual design stage of the system development life cycle.
 This paper presents a procedure to construct DCPS composition models in Petri net formalism using distributed abstractions. The model for each CS is obtained from elementary constructs using compositional operators. The interaction among CSs occurs through channels obtained by connecting send and receive constructs of two CSs participating in an interaction. The internal processing within a CS characterizing its primary function is abstracted in a generic passthrough construct. Representing these constructs with compositional operators results in the complete DCPS model in Petri net formalism. A toolchain with Reference net workshop (Renew) as an integrated Petri net editing and analysis platform is configured to support DCPS modelling, simulation and analysis. The Renew tool functionality has been enhanced with a plugin designed and developed by authors to facilitate the drawing of the distributed composition model.
 A low-level Petri net analysis (Lola) v2.0 plugin is employed to verify the Petri net and temporal properties of the modelled DCPS scenarios. The properties of the resultant model are verified using well-established algorithms to analyze Petri nets. Further, system properties specified using temporal logic can be verified using model-checking algorithms for Petri nets. A moderately complex scenario involving interactions among six CSs illustrates the presented approach.

Design of Fault-Tolerant Distributed Cyber–Physical Systems for Smart Environments

are more and more employed to implement smart environments also in safety-critical scenarios. We here propose a novel system-level design approach capable at considering two relevant aspects of such systems: <inparaenum<i) elaborations together with sensing and actuation need to be placed in the zones where cyber-physical interactions take place, and fault tolerance mechanisms have to be incorporated to tolerate device failures. </inparaenum< The proposed design approach identifies the optimal instantiation of the system architecture and deployment of the applications to minimize the monetary cost of the solution while guaranteeing resource requirements and fault tolerance. Experimental results show that the proposed approach reduces up to 20% the solution cost w.r.t. a straightforward hardening baseline with a computationally viable execution time.

A framework for prototyping Distributed Cyber–Physical Systems with reference nets

It is challenging to ascertain a correct composition of an envisaged Distributed Cyber–Physical System (DCPS) with the user and physical interfaces and requisite interactions. The gap in understanding the user’s ideation and designer’s manifestation in the early stages of the System Development Life Cycle (SDLC) results in requirement errors. These requirement errors result in a higher cost due to rework if discovered in later phases of the SDLC. Hence, there is a need to incorporate dynamic models as system prototypes to facilitate early visibility of the designer’s manifestation to the user community in the requirement engineering phase of SDLC. This paper is an attempt to fill this gap.This paper presents a framework to construct and validate DCPS composition as a rapid prototype. The idea is to facilitate effective communication among the user and developer community. The framework uses Reference net formalism extended with GUI enhancements to achieve the wire-frame implementation of the DCPS prototype under investigation. A containment management scenario in the COVID-19 context illustrates the applicability of the presented framework. The execution of end-to-end scenarios spanning multiple user interfaces with simulated sensors, actuators, and environmental operations within a distributed setup gives a realistic feel of the system operations and dynamics. The presented approach facilitates early validation, identification, and rectification of requirement errors through multiple refinement cycles. In our understanding, this work has not been suggested earlier.

FORECASTING OF THE DISTRIBUTED CYBER-PHYSICAL SYSTEMS STATE

The important component for the solution of the problem of decentralized coordination of the distributed cyber-physical systems (DCPS) control is obtaining of the primary information, needed for searching the optimal control. Such information may be divided into conditional constant – the parameters of the controlled object, and variable – state of the controlled object. Determination of the object parameters is carried out by means of identification problem solution. Object persistence and correspondingly, the possibility of changing its elements state during the coordination cycle stipulates the need to forecast the processes in DCPS. In greater part of the research, dealing with the forecasting problem methods are considered where in this or that way expert assessments and conclusions are used. This concerns mainly social-economic processes, forecasts in the sphere of medicine, education, etc. In the given study the forecasts for the cyber-physical systems are considered, although, in this case models of physical processes and formal methods of the forecasting&nbsp; play far more important role , however, at certain stages expert assessments are also used, in particular, regarding the ranges of possible change of the parameters, list of influencing factors, etc. The prediction method of the state of the distributed cyber-physical systems with the continuous objects on the base of space-time spectral approach to the prediction of DCPS state with continuous and discrete object states has been improved, study of the characteristic of DCPS state prediction has been performed. The possibility of the realization of the prediction method, using the machine learning and simulation modelling has been considered. The expediency of the prediction depth as with the increasing of the depth (interval) of the prediction the fuzziness of the prediction results increases. At the same time, computational resources and time are spent for the prediction. Gradually the situation arises, when the positive effect of the prediction becomes less than the expenses for its realization, this determines the expedient maximum depth of the prediction.

Method and criteria for estimating the emergence and characteristics of architectures of interactive distributed computer and cyberphysical systems

The article analyzes the world level of software and hardware development of control, monitoring and management of complex distributed industrial and environmental facilities. The prospects of development and application of cyberphysical systems on the basis of the methodology of their organization offered by professor AO are noted. Miller. The urgency of solving the problem of synthesis of the theory, methodology and practice of IRKS construction by improving the architectures and data exchange systems of monitoring, interactive and dialogic RKS is emphasized. Based on the emergence criterion proposed by J. Martin, an improved criterion for estimating the emergence of the IRKS data node by taking into account the ratio of the number of reads to the number of data records is proposed. A method for estimating emergence based on the proposed classification of their architectures has been developed. The analysis of advantages and functional limitations of intellectual level of existing RKS architectures is carried out. The proposed architecture of a multilevel star-ring optical sensor network functionally and hardware-adapted to the conditions of application in landscape areas of nature reserves is given.

IA-CPS: Intelligent architecture for cyber-physical systems management

Nowadays, the emergence of large-scale and highly distributed cyber-physical systems (CPSs) in applications including Internet of things (IoT), cloud computing, mobility, Big Data, and sensor networks involves that architecture models have to work in an open and highly dynamic world. This fact increasingly highlights the importance of designing real-time and intelligent CPSs that are capable of decision making. In this paper, an Intelligent Architecture model for CPS management (IA-CPS) based on online processing is proposed for this purpose. Specifically, it can manage simple and complex events based on a service-oriented architecture and directed by an event-driven architecture, using event processing technology as Complex Event Processing (CEP). The novelty of our approach relies on the fact that the proposed architecture is service-oriented, which models the functionalities of the event-driven system. This gives us the possibility to offer a flexible service catalog, allowing us to connect to the system on any kind of device and interact in different scenarios. The model has been applied to two use cases: processing images from video surveillance cameras, and processing of consumption data captured by water and energy sensors installed in end-user environments.

Stabilization of distributed cyber physical systems subject to denial-of-service attack

Cyber Physical Systems (CPS) are defined over the integrations of computation, communication, and control to achieve the desired performance of modern physical processes. It turns out that security threats have a high possibility of affecting CPS and can be affected by several cyber attacks without providing any indication about failure. In this paper, we examine the stabilisation of distributed CPS affected by a denial of service (DoS) attack. First, a static output feedback controller will be designed to achieve the stability of a nominal distributed system. Then, a simple and typical scenario where communication sequence is purely Round-robin is considered and a bound of attack frequency and duration is calculated to ensure the stability of the distributed CPS. Finally, a numerical example is provided to demonstrate the feasibility of the proposed system.

A methodology for the design and deployment of distributed cyber–physical systems for smart environments

The pervasiveness and the growing processing capabilities of mobile and embedded computing systems are leading to a shift from the Internet of Things (IoT) paradigm to the Fog computing scenario where the environment is instrumented with high-performance computing in the proximity to cyber–physical systems. The design of such systems requires an accurate planning, on the one hand, to ensure that specific application requirements will be properly met at run-time, and, on the other hand, to minimize the system’s monetary costs. In this paper we present a methodology for an automated design and deployment of distributed cyber–physical systems into smart environments. We propose an engine based on a Mixed Integer Linear Programming (MILP) formulation which takes in input a planimetry of the environment and a description of the applications and, based on a repository of available processing boards, identifies the cost-optimized instantiation of the processing architecture and the corresponding distribution of the application functionalities. By comparing our proposal with the existing methodologies that address similar problems we can highlight the following novelties: (i) we address a system architecture composed of heterogeneous devices, (ii) we adopt a realistic model of the environment, and (iii) we perform a joint co-exploration of architecture instantiation and applications mapping. An experimental evaluation, considering a smart office case study, demonstrates the potential of the proposed approach in minimizing the overall system monetary cost around 42% w.r.t. a baseline approach not exploiting planimetry information. Such results have been also confirmed by an extensive experimental campaign using synthetic problems, which also highlighted how the execution times of the optimization process are affordable for the design-time process.

Conceptual Verification of Distributed Cyber Physical Systems using Reference Nets

Abstract Verification of conceptual scenarios with interacting cyber physical elements in a distributed setup provides valuable insight to the end users and system designers. After defining a distributed cyber physical system, we present an approach to carry out verification of conceptual scenarios. We build the approach using reference net formalism to model nodes taking part in a distributed conceptual scenario. The model verification is carried out by analyzing outcome of simulation runs. We describe a scenario with requirements of location sharing and textual information exchange among various cyber physical nodes. The applicability of our approach is illustrated with this scenario. The publish-subscribe paradigm of information exchange is used to mediate interaction among nodes. The presented formulation will lead to faster convergence towards requirement consolidation (among end users, system designers, and developers).

STC: Sub-packetization tunable codes for fast recovery

Abstract In distributed cyber-physical systems, the data should be stored in a reliable and available manner in the face of multiple kinds of failures. Considering that the storage space is an expensive part, erasure codes are storage-efficient alternatives to replication for fault tolerance. However, traditional erasure codes, e.g. Reed–Solomon (RS) codes, impose a huge burden on disk I/O and network resources for recovering unavailable data in case of node failures. In this paper, we introduce a new set of erasure codes called Sub-packetization Tunable Codes (STC). STC can reduce the amount of required information during recovering a failed block, while still allowing a significant reduction in storage overhead. The customized recovery method in STC needs each block to be sub-packetized, and the repair bandwidth decreases as the number of sub-packets increases. However, high sub-packetization may result in some extra costs. In STC, the sub-packetization level of our codes is tunable so that storage systems can weigh the balance between sub-packetization costs and repair bandwidth. In addition, our STC can be constructed as a family of double regenerating codes (DRC) to improve the repair performance in hierarchical distributed situations, whose idea is to trade the abundant inner-rack bandwidth for constrained cross-rack bandwidth.

Guest Editorial: Special Issue on (Industrial) Internet-of-Things for Smart and Sensing Systems: Issues, Trends, and Applications

Smart and sensing systems represent a significant research theme that has motivated a number of research initiatives around the world. Smart systems typically consist of different components, including sensors for signal acquisition, communication units for data transmission between components, control, and management units for decision-making, and actuators to perform the appropriate actions. They have impacted applications in many fields, such as manufacturing, healthcare, energy, environment, logistic, defence, monitoring, and mobility. As the complexity of such systems continue to grow, the challenge of developing integrated smart and sensing systems has surpassed the design complexity of their individual components. A smart and sensing system may include a large number of heterogeneous components, subsystems, smart and intelligent sensors, and may combine several correlated functionalities. Thus, the main issue of developing smart and sensing systems lies in the complexity to integrate and to manage these different components, technologies, and goals across a wide spectrum. In recent years, the emergence of the Internet of Things (IoT) has amplified the capacity of sensing the world through a network of connected devices using the existing network infrastructure. Grouping together smart and sensing systems in an IoT setting to form large-scale distributed cyber-physical systems has tremendous potential in bringing smart systems to many application domains.

Design of Distributed Cyber–Physical Systems for Connected and Automated Vehicles With Implementing Methodologies

With the development of communication and control technology, intelligent transportation systems (ITS) have received increasing attention from both industry and academia. However, plenty of studies providing different formulations for ITS depend on Master Control Center and require a high level of hardware configuration. The systematized technologies for distributed architectures are still not explored in detail. In this paper, we proposed a novel distributed cyber–physical system for connected and automated vehicles, and related methodologies are illustrated. Every vehicle in this system is modeled as a double-integrator and supposed to travel along a desired trajectory for maintaining a rigid formation geometry. The desired trajectory is generated by reference leading vehicles using information from multiple sources, while ordinary following vehicles use velocity and position information from their nearest neighbors and sensor information from on-board sensors to correct their own performance. Information graphs are used to illustrate the interaction topology between connected and automated vehicles. Edge computing technology is used to analyze and process information, such that the risk of privacy leaks can be greatly reduced. The performance scaling laws for the network with a one-dimensional information graph are generalized to networks with D -dimensional information graphs, and the results of the experiments show that the performance of the connected and automated vehicles matches very well with analytic predictions. Some design guidelines and open questions are provided for the future study.

The Entropy Based Approach to Modeling and Evaluating Autonomy and Intelligence of Robotic Systems

This review paper presents the Entropy approach to modeling and performance evaluation of Intelligent Machines (IMs), which are modeled as hierarchical, multi-level structures. It provides a chronological summary of developments related to intelligent control, from its origins to current advances. It discusses fundamentals of the concept of Entropy as a measure of uncertainty and as a control function, which may be used to control, evaluate and improve through adaptation and learning performance of engineering systems. It describes a multi-level, hierarchical, architecture that is used to model such systems, and it defines autonomy and machine intelligence for engineering systems, with the aim to set foundations necessary to tackle related challenges. The modeling philosophy for the systems under consideration follows the mathematically proven principle of Increasing Precision with Decreasing Intelligence (IPDI). Entropy is also used in the context of N-Dimensional Information Theory to model the flow of information throughout such systems and contributes to quantitatively evaluate uncertainty, thus, autonomy and intelligence. It is explained how Entropy qualifies as a unique, single, measure to evaluate autonomy, intelligence and precision of task execution. The main contribution of this review paper is that it brings under one forum research findings from the 1970’s and 1980’s, and that it supports the argument that even today, given the unprecedented existing computational power, advances in Artificial Intelligence, Deep Learning and Control Theory, the same foundational framework may be followed to study large-scale, distributed Cyber Physical Systems (CPSs), including distributed intelligence and multi-agent systems, with direct applications to the SmartGrid, transportation systems and multi-robot teams, to mention but a few applications.

Distributed Execution of Scenario-based Specifications of Structurally Dynamic Cyber-Physical Systems

Cyber-physical systems are found in many areas, e.g., manufacturing or smart cities. They consist of multiple components that cooperate to provide the desired functionality. This need for cooperation causes complex interactions between components, which makes developing cyber-physical systems difficult, especially systems whose component structure changes dynamically at runtime. We have created a formal, scenario-based specification method which makes it easier to develop distributed cyber-physical systems. We previously presented an approach for the distributed execution of such specifications based on naive and inefficient broadcasting. In this paper we propose a more efficient approach which uses the available network resources more economically.

Designing and verifying distributed cyber-physical systems using Multirate PALS: An airplane turning control system case study

Distributed cyber-physical systems (DCPS), such as aeronautics and ground transportation systems, are very hard to design and verify, because of asynchronous communication, network delays, and clock skews. Their model checking verification typically becomes unfeasible due to the huge state space explosion caused by the system's concurrency. The Multirate PALS (“physically asynchronous, logically synchronous”) methodology has been proposed to reduce the design and verification of a DCPS to the much simpler task of designing and verifying its underlying synchronous version, where components may operate with different periods. This paper presents a methodology for formally modeling and verifying multirate DCPSs using Multirate PALS. In particular, this methodology explains how to deal with the system's physical environment in Multirate PALS. We illustrate our methodology with a multirate DCPS consisting of an airplane maneuvered by a pilot, who turns the airplane to a specified angle through a distributed control system. Our formal analysis using Real-Time Maude revealed that the original design did not achieve a smooth turning maneuver, and led to a redesign of the system. We then use model checking and Multirate PALS to prove that the redesigned system satisfies the desired correctness properties, whereas model checking the corresponding asynchronous model is unfeasible. This shows that Multirate PALS is not only effective for formal DCPS verification, but can also be used effectively in the DCPS design process.

Validated Real Time Middle Ware For Distributed Cyber Physical Systems Using Hmm

Distributed Cyber Physical Systems designed for different scenario must be capable enough to perform in an efficient manner in every situation. E arlier approaches, such as CORBA, has performed but with different time constraints. Therefore, there was the need to design reconfigurable, robust, validated and consistent real time middle ware systems with end -to-end timing. In the DCPS-HMM we have proposed the processor efficiency and data validation which may proof crucial in implementing various distributed systems such as credit card systems o r file transfer through network.

Current Studies On Intrusion Detection System, Genetic Algorithm And Fuzzy Logic

Distributed Cyber Physical Systems designed for different scenario must be capable enough to perform in an efficient manner in every situation. Earlier approaches, such as CORBA, has performed but with different time constraints. Therefore, there was the need to design reconfigurable, robust, validated and consistent real time middle ware systems with end-to-end timing. In the DCPS-HMM we have proposed the processor efficiency and data validation which may proof crucial in implementing various distributed systems such as credit card systems or file transfer through network.

PALS-Based Analysis of an Airplane Multirate Control System in Real-Time Maude

Distributed cyber-physical systems (DCPS) are pervasive in areas such as aeronautics and ground transportation systems, including the case of distributed hybrid systems. DCPS design and verification is quite challenging because of asynchronous communication, network delays, and clock skews. Furthermore, their model checking verification typically becomes unfeasible due to the huge state space explosion caused by the system's concurrency. The PALS ("physically asynchronous, logically synchronous") methodology has been proposed to reduce the design and verification of a DCPS to the much simpler task of designing and verifying its underlying synchronous version. The original PALS methodology assumes a single logical period, but Multirate PALS extends it to deal with multirate DCPS in which components may operate with different logical periods. This paper shows how Multirate PALS can be applied to formally verify a nontrivial multirate DCPS. We use Real-Time Maude to formally specify a multirate distributed hybrid system consisting of an airplane maneuvered by a pilot who turns the airplane according to a specified angle through a distributed control system. Our formal analysis revealed that the original design was ineffective in achieving a smooth turning maneuver, and led to a redesign of the system that satisfies the desired correctness properties. This shows that the Multirate PALS methodology is not only effective for formal DCPS verification, but can also be used effectively in the DCPS design process, even before properties are verified.