Pulverization in Cyber-Physical Systems: Engineering the Self-Organizing Logic Separated from Deployment

Abstract

Emerging cyber-physical systems, such as robot swarms, crowds of augmented people, and smart cities, require well-crafted self-organizing behavior to properly deal with dynamic environments and pervasive disturbances. However, the infrastructures providing networking and computing services to support these systems are becoming increasingly complex, layered and heterogeneous—consider the case of the edge–fog–cloud interplay. This typically hinders the application of self-organizing mechanisms and patterns, which are often designed to work on flat networks. To promote reuse of behavior and flexibility in infrastructure exploitation, we argue that self-organizing logic should be largely independent of the specific application deployment. We show that this separation of concerns can be achieved through a proposed “pulverization approach”: the global system behavior of application services gets broken into smaller computational pieces that are continuously executed across the available hosts. This model can then be instantiated in the aggregate computing framework, whereby self-organizing behavior is specified compositionally. We showcase how the proposed approach enables expressing the application logic of a self-organizing cyber-physical system in a deployment-independent fashion, and simulate its deployment on multiple heterogeneous infrastructures that include cloud, edge, and LoRaWAN network elements.

Digital Twins, Virtual Devices, and Augmentations for Self-Organising Cyber-Physical Collectives

“…The most straightforward deployment is where each DT is hosted by the corresponding PT, but more complex systems can be designed. The pulverisation meta-model [11] provides exactly that: a partitioning schema and formal model for describing deployments of self-organising Cyber-Physical Systems like aggregate computing systems. However, previous research on aggregate computing and pulverisation model did not explicitly consider the notions like digital twin, virtual device, and the other concepts introduced in Section 2.2.…”

“…In this paper, we focus on self-organising Cyber-Physical Systems [10,11], namely collectives of physical devices monitored and controlled by computer-based algorithms that allow them to autonomously organise as a whole towards global goals. In this context, we sustain a vision whereby logical representations of system entities (e.g., digital twins and virtual devices) are key for: (i) separation of concerns in system design and implementation [11,12]; and (ii) achieving improved application cost/performance profiles, for example, through smart deployment or controlled augmentation of the system to improve or facilitate self-organisation processes [13][14][15]. Our position is also that programming approaches to self-organisation can especially benefit from such logical representations, for example, in terms of separation of concerns, declarativity, modularity, and execution optimisability.…”

“…In particular, we address the problem of modular abstraction and the design of selforganising Cyber-Physical Systems. We aim to address it by decoupling cyber vs. physical components, as per [11], decoupling virtual devices from twinning relationships, and devising corresponding modelling concepts at a collective level. Indeed, in this work, we provide the following contributions:…”

“…We review from literature various kinds of logical devices, and provide a conceptual characterisation including digital twins, virtual devices, and "collective" devices. We do so by distinguishing between the relationships of identity correspondence and execution existing between logical and physical devices, and by taking both an individual and collective stance (Section 2); • We re-interpret and conceptually extend the meta-model of self-organising Cyber-Physical Systems presented in [11] in light of the novel proposed concepts, especially discussing how it can express a notion of augmented collective digital twin considering digital twins and virtual devices by a global perspective; •…”

A Programming Approach to Collective Autonomy

“…Variants of such a control architecture can also be envisaged, e.g., by considering asynchronicity and different rates for context evaluation, computation, and action. Preliminary work supporting this direction can be found in [37,38], where partitioning schemas and programmable schedulers are proposed.…”