Special Issue "Challenges and Directions Forward for Dealing with the Complexity of Future Smart Cyber–Physical Systems"

A special issue of Designs (ISSN 2411-9660).

Deadline for manuscript submissions: closed (30 September 2018).

Special Issue Editors

Guest Editor
Prof. Dr. Martin Törngren

Department of Machine Design, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden
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Interests: Cyber–Physical Systems (CPS) and systems engineering; design methodology; model based engineering incl. model and tool interoperability; architectures of embedded and cyber–physical systems; co-design of control and embedded computer systems; system and functional safety; autonomous machines and trustworthy AI; innovation eco-systems; life-long learning and education
Guest Editor
Ms. Didem Gürdür

Department of Machine Design, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden
Website | E-Mail
Interests: Cyber–Physical Systems; interoperability; tool integration; data analytics; data visualisations; visual analytics
Guest Editor
Dr. Elena Fersman

Ericsson Research, Ericsson AB, 16480 Stockholm, Sweden
Department of Machine Design, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden
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Interests: modeling and analysis of Cyber-Physical Systems; knowledge representation, knowledge management and decision support
Guest Editor
Prof. Dr. Harold (Bud) Lawson

Lawson Konsult AB
Website | E-Mail
Interests: complex systems; systems thinking; systems engineering; software engineering
Guest Editor
Dr. Vincent Aravantinos

Fortiss GmbH, 80805 Munich, Germany
Website | E-Mail
Interests: autonomous systems; software architecture; cyber-physical systems engineering

Special Issue Information

Dear Colleagues,

A key aspect of Cyber-Physical Systems (CPS) is their potential for integrating information technologies, operational technologies (in terms of embedded systems and control systems), and physical systems, to form new or improved functionalities. CPS, thus, draws upon advances in many areas. This positioning provides unprecedented opportunities for innovation, within and across existing domains. However, at the same time, it is commonly understood that we are already stretching the limits of existing methodologies.

In embarking towards CPS with such unprecedented capabilities it becomes essential to improve our understanding of CPS complexity and how we can deal with it. Complexity has many facets including complexity of the CPS itself, of the environments in which the CPS acts, and in terms of the organizations and supporting tools that develop, operate and maintain CPS.

The primary objective of this Special Issue is to provide a forum for researchers and practitioners to exchange their latest achievements and to identify critical issues, challenges, opportunities and future directions for how to deal with the complexity of future CPS. Contributions covering methods, tools, architectures, foundational aspects as well as organizational and other complexity-related aspects are welcomed.

Dr. Vincent Aravantinos
Ms. Didem Gürdür
Dr. Elena Fersman
Prof. Dr. Martin Törngren
Prof. Dr. Harold (Bud) Lawson
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Designs is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • methodologies for dealing with complexity

  • analyzing or characterizing complexity of CPS

  • what are the key facets of the cyber- vs. the physical vs. cyber-physical complexity?

  • foundational theories for CPS engineering

  • composability approaches for CPS

  • systematic approaches for dealing with uncertainty

  • systematic approaches for dealing with interfaces and interrelations

  • dealing with trustworthiness and trade-offs (e.g. safety vs. security vs. availability vs. cost)

  • reconciling software and hardware processes and life-spans

  • smartness of CPS and complexity management, leveraging AI

  • robustness of CPS, dealing with AI and complex environments

  • cyber-physical systems of systems-ensuring proper interactions at the SoS level

  • managing organizational complexity

Published Papers (10 papers)

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Open AccessArticle
A full Model-Based Design Environment for the Development of Cyber Physical Systems
Received: 30 September 2018 / Revised: 3 February 2019 / Accepted: 9 February 2019 / Published: 13 February 2019
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Abstract
This paper discusses a full model-based design approach in the applicative development of Cyber Physical Systems targeting the fast development of Logic controllers (i.e., the “Cyber” side of a CPS). The proposed modeling language provides a synthesis between various somehow conflicting constraints, such [...] Read more.
This paper discusses a full model-based design approach in the applicative development of Cyber Physical Systems targeting the fast development of Logic controllers (i.e., the “Cyber” side of a CPS). The proposed modeling language provides a synthesis between various somehow conflicting constraints, such as being graphical, easily usable by designers, self-contained with no need for extra information, and to leads to efficient implementation, even in low-end embedded systems. Its main features include easiness to describe parallelism of actions, precise time handling, communication with other systems according to various interfaces and protocols. Taking advantage the modeling easiness deriving from the above features, the language encourages to model whole CPSs, that is their Logical and their Physical side, working together; such whole models are simulated in order to achieve insight about their interaction and spot possible flaws in the controller; once validated, the very same model, without the Physical side, is compiled and into the logic controller, ready to be flashed on the controller board and to interact with the physical side. The discussed language has been implemented into a real model-based development environment, TaskScript, in use since a few years in the development of production grade systems. Results about its effectiveness in terms of model expressivity and design effort are presented; such results show the effectiveness of the approach: real case production grade systems have been developed and tested in a few days. Full article
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Open AccessArticle
A Lazy Bailout Approach for Dual-Criticality Systems on Uniprocessor Platforms
Received: 20 October 2018 / Revised: 16 November 2018 / Accepted: 28 January 2019 / Published: 1 February 2019
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Abstract
A challenge in the design of cyber-physical systems is to integrate the scheduling of tasks of different criticality, while still providing service guarantees for the higher critical tasks in the case of resource-shortages caused by faults. While standard real-time scheduling is agnostic to [...] Read more.
A challenge in the design of cyber-physical systems is to integrate the scheduling of tasks of different criticality, while still providing service guarantees for the higher critical tasks in the case of resource-shortages caused by faults. While standard real-time scheduling is agnostic to the criticality of tasks, the scheduling of tasks with different criticalities is called mixed-criticality scheduling. In this paper, we present the Lazy Bailout Protocol (LBP), a mixed-criticality scheduling method where low-criticality jobs overrunning their time budget cannot threaten the timeliness of high-criticality jobs while at the same time the method tries to complete as many low-criticality jobs as possible. The key principle of LBP is instead of immediately abandoning low-criticality jobs when a high-criticality job overruns its optimistic WCET estimate, to put them in a low-priority queue for later execution. To compare mixed-criticality scheduling methods, we introduce a formal quality criterion for mixed-criticality scheduling, which, above all else, compares schedulability of high-criticality jobs and only afterwards the schedulability of low-criticality jobs. Based on this criterion, we prove that LBP behaves better than the original Bailout Protocol (BP). We show that LBP can be further improved by slack time exploitation and by gain time collection at runtime, resulting in LBPSG. We also show that these improvements of LBP perform better than the analogous improvements based on BP. Full article
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Open AccessArticle
Adaptive Time-Triggered Multi-Core Architecture
Received: 27 September 2018 / Revised: 7 December 2018 / Accepted: 18 January 2019 / Published: 22 January 2019
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Abstract
The static resource allocation in time-triggered systems offers significant benefits for the safety arguments of dependable systems. However, adaptation is a key factor for energy efficiency and fault recovery in Cyber-Physical System (CPS). This paper introduces the Adaptive Time-Triggered Multi-Core Architecture (ATMA), which [...] Read more.
The static resource allocation in time-triggered systems offers significant benefits for the safety arguments of dependable systems. However, adaptation is a key factor for energy efficiency and fault recovery in Cyber-Physical System (CPS). This paper introduces the Adaptive Time-Triggered Multi-Core Architecture (ATMA), which supports adaptation using multi-schedule graphs while preserving the key properties of time-triggered systems including implicit synchronization, temporal predictability and avoidance of resource conflicts. ATMA is an overall architecture for safety-critical CPS based on a network-on-a-chip with building blocks for context agreement and adaptation. Context information is established in a globally consistent manner, providing the foundation for the temporally aligned switching of schedules in the network interfaces. A meta-scheduling algorithm computes schedule graphs and avoids state explosion with reconvergence horizons for events. For each tile, the relevant part of the schedule graph is efficiently stored using difference encodings and interpreted by the adaptation logic. The architecture was evaluated using an FPGA-based implementation and example scenarios employing adaptation for improved energy efficiency. The evaluation demonstrated the benefits of adaptation while showing the overhead and the trade-off between the degree of adaptation and the memory consumption for multi-schedule graphs. Full article
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Open AccessArticle
A Two-Layer Component-Based Allocation for Embedded Systems with GPUs
Received: 14 December 2018 / Revised: 12 January 2019 / Accepted: 16 January 2019 / Published: 19 January 2019
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Abstract
Component-based development is a software engineering paradigm that can facilitate the construction of embedded systems and tackle its complexities. The modern embedded systems have more and more demanding requirements. One way to cope with such a versatile and growing set of requirements is [...] Read more.
Component-based development is a software engineering paradigm that can facilitate the construction of embedded systems and tackle its complexities. The modern embedded systems have more and more demanding requirements. One way to cope with such a versatile and growing set of requirements is to employ heterogeneous processing power, i.e., CPU–GPU architectures. The new CPU–GPU embedded boards deliver an increased performance but also introduce additional complexity and challenges. In this work, we address the component-to-hardware allocation for CPU–GPU embedded systems. The allocation for such systems is much complex due to the increased amount of GPU-related information. For example, while in traditional embedded systems the allocation mechanism may consider only the CPU memory usage of components to find an appropriate allocation scheme, in heterogeneous systems, the GPU memory usage needs also to be taken into account in the allocation process. This paper aims at decreasing the component-to-hardware allocation complexity by introducing a two-layer component-based architecture for heterogeneous embedded systems. The detailed CPU–GPU information of the system is abstracted at a high-layer by compacting connected components into single units that behave as regular components. The allocator, based on the compacted information received from the high-level layer, computes, with a decreased complexity, feasible allocation schemes. In the last part of the paper, the two-layer allocation method is evaluated using an existing embedded system demonstrator; namely, an underwater robot. Full article
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Open AccessArticle
A Computational Framework for Procedural Abduction Done by Smart Cyber-Physical Systems
Received: 11 October 2018 / Revised: 18 December 2018 / Accepted: 19 December 2018 / Published: 25 December 2018
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Abstract
To be able to provide appropriate services in social and human application contexts, smart cyber-physical systems (S-CPSs) need ampliative reasoning and decision-making (ARDM) mechanisms. As one option, procedural abduction (PA) is suggested for self-managing S-CPSs. PA is a knowledge-based computation and learning mechanism. [...] Read more.
To be able to provide appropriate services in social and human application contexts, smart cyber-physical systems (S-CPSs) need ampliative reasoning and decision-making (ARDM) mechanisms. As one option, procedural abduction (PA) is suggested for self-managing S-CPSs. PA is a knowledge-based computation and learning mechanism. The objective of this article is to provide a comprehensive description of the computational framework proposed for PA. Towards this end, first the essence of smart cyber-physical systems is discussed. Then, the main recent research results related to computational abduction and ampliative reasoning are discussed. PA facilitates beliefs-driven contemplation of the momentary performance of S-CPSs, including a ‘best option’-based setting of the servicing objective and realization of any demanded adaptation. The computational framework of PA includes eight clusters of computational activities: (i) run-time extraction of signals and data by sensing, (ii) recognition of events, (iii) inferring about existing situations, (iv) building awareness of the state and circumstances of operation, (v) devising alternative performance enhancement strategies, (vi) deciding on the best system adaptation, (vii) devising and scheduling the implied interventions, and (viii) actuating effectors and controls. Several cognitive algorithms and computational actions are used to implement PA in a compositional manner. PA necessitates not only a synergic interoperation of the algorithms, but also an objective-dependent fusion of the pre-programmed and the run time acquired chunks of knowledge. A fully fledged implementation of PA is underway, which will make verification and validation possible in the context of various smart CPSs. Full article
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Open AccessArticle
Sharpening the Scythe of Technological Change: Socio-Technical Challenges of Autonomous and Adaptive Cyber-Physical Systems
Received: 28 September 2018 / Revised: 20 November 2018 / Accepted: 21 November 2018 / Published: 28 November 2018
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Abstract
Autonomous and Adaptative Cyber-Physical Systems (ACPS) represent a new knowledge frontier of converging “nano-bio-info-cogno” technologies and applications. ACPS have the ability to integrate new ‘mutagenic’ technologies, i.e., technologies able to cause mutations in the society. Emerging approaches, such as artificial intelligence techniques and [...] Read more.
Autonomous and Adaptative Cyber-Physical Systems (ACPS) represent a new knowledge frontier of converging “nano-bio-info-cogno” technologies and applications. ACPS have the ability to integrate new ‘mutagenic’ technologies, i.e., technologies able to cause mutations in the society. Emerging approaches, such as artificial intelligence techniques and deep learning, enable exponential speedups for supporting increasingly higher levels of autonomy and self-adaptation. In spite of this disruptive landscape, however, deployment and broader adoption of ACPS in safety-critical scenarios remains challenging. In this paper, we address some challenges that are stretching the limits of ACPS safety engineering, including tightly related aspects such as ethics and resilience. We argue that a paradigm change is needed that includes the entire socio-technical aspects, including trustworthiness, responsibility, liability, as well as the ACPS ability to learn from past events, anticipate long-term threads and recover from unexpected behaviors. Full article
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Open AccessArticle
Developing Self-Similar Hybrid Control Architecture Based on SGAM-Based Methodology for Distributed Microgrids
Received: 1 August 2018 / Revised: 10 October 2018 / Accepted: 18 October 2018 / Published: 23 October 2018
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Abstract
Cyber-Physical Systems (CPS) are the complex systems that control and coordinate physical infrastructures, which may be geographically apart, via the use of Information and Communication Technology (ICT). One such application of CPS is smart microgrids. Microgrids comprise both power consuming and power producing [...] Read more.
Cyber-Physical Systems (CPS) are the complex systems that control and coordinate physical infrastructures, which may be geographically apart, via the use of Information and Communication Technology (ICT). One such application of CPS is smart microgrids. Microgrids comprise both power consuming and power producing infrastructure and are capable of operating in grid connected and disconnected modes. Due to the presence of heterogeneous smart devices communicating over multiple communication protocols in a distributed environment, a system architecture is required. The objective of this paper is to approach the microgrid architecture from the software and systems’ design perspective. The architecture should be flexible to support various multiple communication protocols and is able to integrate various hardware technologies. It should also be modular and scalable to support various functionalities such as island mode operations, energy efficient operations, energy trading, predictive maintenance, etc. These requirements are the basis for designing the software architecture for the smart microgrids that should be able to manage not only electrical but all energy related systems. In this work, we propose a distributed, hybrid control architecture suited for microgrid environments, where entities are geographically distant and need to operate in a cohesive manner. The proposed system architecture supports various design philosophies such as component-based design, hierarchical composition of components, peer-to-peer design, distributed decision-making and controlling as well as plug-and-play during runtime. A unique capability of the proposed system architecture is the self-similarity of the components for the distributed microgrids. The benefit of the approach is that it supports these design philosophies at all the levels in the hierarchy in contrast to a typical centralized architectures where decisions are taken only at the global level. The proposed architecture is applied to a real system of 13 residential buildings in a low-voltage distribution network. The required implementation and deployment details for monitoring and controlling 13 residential buildings are also discussed in this work. Full article
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Open AccessArticle
How to Deal with the Complexity of Future Cyber-Physical Systems?
Received: 30 September 2018 / Revised: 19 October 2018 / Accepted: 19 October 2018 / Published: 22 October 2018
Cited by 2 | PDF Full-text (352 KB) | HTML Full-text | XML Full-text
Abstract
Cyber-Physical Systems (CPS) integrate computation, networking and physical processes to produce products that are autonomous, intelligent, connected and collaborative. Resulting Cyber-Physical Systems of Systems (CPSoS) have unprecedented capabilities but also unprecedented corresponding technological complexity. This paper aims to improve understanding, awareness and methods [...] Read more.
Cyber-Physical Systems (CPS) integrate computation, networking and physical processes to produce products that are autonomous, intelligent, connected and collaborative. Resulting Cyber-Physical Systems of Systems (CPSoS) have unprecedented capabilities but also unprecedented corresponding technological complexity. This paper aims to improve understanding, awareness and methods to deal with the increasing complexity by calling for the establishment of new foundations, knowledge and methodologies. We describe causes and effects of complexity, both in general and specific to CPS, consider the evolution of complexity, and identify limitations of current methodologies and organizations for dealing with future CPS. The lack of a systematic treatment of uncertain complex environments and “composability”, i.e., to integrate components of a CPS without negative side effects, represent overarching limitations of existing methodologies. Dealing with future CPSoS requires: (i) increased awareness of complexity, its impact and best practices for how to deal with it, (ii) research to establish new knowledge, methods and tools for CPS engineering, and (iii) research into organizational approaches and processes to adopt new methodologies and permit efficient collaboration within and across large teams of humans supported by increasingly automated computer aided engineering systems. Full article
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Open AccessArticle
Fighting CPS Complexity by Component-Based Software Development of Multi-Mode Systems
Received: 7 October 2018 / Revised: 14 October 2018 / Accepted: 18 October 2018 / Published: 22 October 2018
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Abstract
Growing software complexity is an increasing challenge for the software development of modern cyber-physical systems. A classical strategy for taming this complexity is to partition system behaviors into different operational modes specified at design time. Such a multi-mode system can change behavior by [...] Read more.
Growing software complexity is an increasing challenge for the software development of modern cyber-physical systems. A classical strategy for taming this complexity is to partition system behaviors into different operational modes specified at design time. Such a multi-mode system can change behavior by switching between modes at run-time. A complementary approach for reducing software complexity is provided by component-based software engineering (CBSE), which reduces complexity by building systems from composable, reusable and independently developed software components. CBSE and the multi-mode approach are fundamentally conflicting in that component-based development conceptually is a bottom-up approach, whereas partitioning systems into operational modes is a top-down approach with its starting point from a system-wide perspective. In this article, we show that it is possible to combine and integrate these two fundamentally conflicting approaches. The key to simultaneously benefiting from the advantages of both approaches lies in the introduction of a hierarchical mode concept that provides a conceptual linkage between the bottom-up component-based approach and system level modes. As a result, systems including modes can be developed from reusable mode-aware components. The conceptual drawback of the approach—the need for extensive message exchange between components to coordinate mode-switches—is eliminated by an algorithm that collapses the component hierarchy and thereby eliminates the need for inter-component coordination. As this algorithm is used from the design to implementation level (“compilation”), the CBSE design flexibility can be combined with efficiently implemented mode handling, thereby providing the complexity reduction of both approaches, without inducing any additional design or run-time costs. At the more specific level, this article presents (1) a mode mapping mechanism that formally specifies the mode relation between composable multi-mode components and (2) a mode transformation technique that transforms component modes to system-wide modes to achieve efficient implementation. Full article
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Open AccessCorrection
Correction: Sharpening the Scythe of Technological Change: Socio-Technical Challenges of Autonomous and Adaptive Cyber-Physical Systems
Received: 30 January 2019 / Accepted: 31 January 2019 / Published: 11 February 2019
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Abstract
We, the authors, wish to make the following corrections to our paper [...] Full article
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