Cyber-Physical Systems: When the Embedded World Meets the Virtual World

The term “cyber-physical systems” (CPS) refers to a new generation of computational systems that expand the capabilities of the physical world, enabling radically new modalities of interaction with people. Following the definition provided by Lee, ¹ in CPS, embedded computers and networks monitor and control the physical processes, usually with feedback loops where physical processes affect computations and vice versa.

CPS are regarded as one of the key enabling technologies of the so-called Industry 4.0 revolution. By embedding computational capability in every physical component, CPS can potentially transform entire economic sectors of our society, from transportation to manufacturing, from healthcare to urban infrastructure. Relatively simple examples of CPS are a computer chip that deploys an airbag when detecting an accident, or a car-to-car communication system that allows multiple vehicles to “talk” with each other to make traffic safer and more efficient.

A CPS architecture includes three key components: sensors, actuators, and decentralized intelligence. Embedded sensors allow a CPS to detect its operational status and spatio-temporal coordinates automatically within the environment where it is situated. Actuators are the means by which the CPS control and manipulate the physical environment, for example to optimize a specific process. Finally, decentralized intelligence refers to the possibility of providing networked objects with their own management and control systems, thus enabling independent process management. The combination of these features allows for data acquisition/generation, computational treatment of gathered data, and support for the decision-making process.

By implementing these scenarios, CPS makes the boundaries between physical and the virtual worlds disappear, allowing a double causal relationship: the processes taking place in the physical world can affect the ones occurring in the virtual world, and vice versa. However, it should be noted that CPS is not the same concept as the Internet of Things (IoT), although these notions are sometimes used interchangeably. Actually, IoT is what makes CPS possible by enabling the exchange of information between physical (or virtual) endpoints.

A fundamental challenge of this emerging technological paradigm is how to model the interaction between people and CPS. By definition, CPS implies a wide spectrum of interaction modalities, which multiplies in virtual realms the degrees of freedom that are already available in the physical realm. This means that in the CPS vision, people will increasingly live in “hybrid” ecosystems, in which their actions will be seamlessly augmented and supported by means of autonomous artificial systems. On the other hand, this “cyberization of the physical” implies that people's behavior will be continuously logged, monitored, analyzed, and translated into computational models to enable these services and applications to be effectively delivered. Actually, in a CPS, the physical world itself—including the human body—becomes the interface. Thus, the introduction of this paradigm will require the development of new theoretical and methodological approaches to understand and model user experience within systems with embedded intelligence. Security is another key challenge that needs to be addressed for the CPS vision to be turned into reality. Since CPS will be integrated in the very physical environment, these smart services will have a transformative impact on our daily lives. On the other hand, the increased adoption of CPS will also bring more vulnerabilities to both our digital and physical environments. Thus, putting the user at the center and identifying effective design strategies for ensuring privacy, security, and robustness are important steps to take in order to maximize the (positive) impact of CPS.