A Practical Introduction to Human-in-the-Loop Cyber-Physical Systems

Chapter 2Evolution of HiTL Technologies

As we discussed in the introductory chapter of this book, the technological progress of the last few decades has been particularly remarkable. Still, how did all of this come to be? First, in Section 2.1, we will see how researchers began to address and understand the scope of simple “things”, and we will subsequently consider work that targeted more complex and larger environments. Finally, in Section 2.2, we will discuss more recent examples of monitoring of human beings.

2.1 “Things”, Sensors, and the Real World

The linkage of physical objects and sensors to the Internet and their integration with web and enterprise applications has long been considered in the literature. As previously mentioned, early works began by proposing the use of physical tokens (such as barcodes or electronic tags) to relate objects to the web. An example of such an approach was described in [1], as Figure 2.1 illustrates. Since these early times, researchers were concerned with the heterogeneity and complexity of the available network protocols. In the world of pervasive computing, “client devices” like PDAs were used to access services on “server devices” like printers, light switches, or smart home appliances. Since these regular server devices have limited computation, memory, and power capabilities, they require extremely small and inexpensive servers that consist of low-performance micro controllers with only a few kilobytes of memory. However, they ...