Conceptualizing smartness of CPSs

The rapid technological advancement that enhances the smartness of cyber-physical systems (CPSs) creates the need to assure their robustness against unintended and deliberate disturbances. However, balancing smartness and robustness of CPSs is neither intuitive nor simple, but requires the definition of each concept to be formulated and established, along with the dimensions and features that make CPSs smart and robust.

The goal of the study is to identify a representative set of definitions and characteristics that compose and describe a smart system in various contexts supported by a literature review in the two major digital libraries (Scopus and Web of Science). We selected the ones that are not only relevant but also crucial for characterizing a CPS as smart.

This creates a foundation for our efforts towards finding a balance between smartness and robustness of CPSs, to a comprehensive safety and security risk analysis of such systems. The focus of scientific research on smartness has increased significantly over the last decade starting from almost no publications in 2010 to 185 and 122 in 2018 in Scopus and WoS respectively.

The main subject areas are Computer Science, including various specific sub-areas, such as Information Systems and Artificial Intelligence, and Engineering. Similarly, all the articles selected, based on the specific criteria, through the literature review, have been published over the last 6 years, with their vast majority to be from 2016 onwards.

Smartness of modern cities including all their structural elements, such as infrastructure, transportation, education and governance, is the main concept assessed in the literature. The assessment approaches can be grouped in three categories, namely a systemic, anthropocentric and a technological one, all mentioning the importance of information and communication technologies (ICTs) to the enhancement of smartness.

Several definitions of smartness and its key characteristics identified in the literature review with the most important input to be from publications assessing the term from a systemic and technological perspective, as opposed to the human-centered ones, characterizing interconnected computer-based systems that are sensing and interact with the physical environment.

Motivated by the similarities between these systems and what Carreras Guzman et al., [2] define as CPS, and inspired by the recent work of Alter, [1], we define the smartness dimensions of CPSs as: (1) degree of integration, (2) real-time feedback control, (3) degree of cooperative control and (4) level of automation, describing also the smartness characteristics of each dimension.

This study supplements the research efforts of our group and forms a foundation towards finding a balance between smartness and robustness of CPSs, by providing the conceptual framework to support a comprehensive safety and security risk analysis.