The Internet of Things (IoT) begins with sources of data or devices that perform an action. These we call endpoints, and they are the things associated with the internet. When one discusses IoT, in general, the actual sources of data are often overlooked. These sources are sensors outputting a stream of time-correlated data that must be transmitted securely, possibly analyzed, and possibly stored. The value of IoT is in the data in aggregate. Therefore, the data a sensor provides is crucial. However, for an architect, it is critical to understand the data as well as how the data is interpreted. Besides understanding what data is collected and how it is acquired, in a massive IoT deployment, it is useful to know what can be sensed, and what the constraints are for various sensors. For example, a system must account for lost devices and erroneous data. An architect must understand the reasons why data may not be reliable from sensors, and how a sensor can fail in the field. Essentially, we are connecting the analog world to the digital. The majority of connected things will be sensors, so it is important to understand their role.
This is what the IoT is in a nutshell. The massive growth of connected things and objects will be sensors and actuators, so it is important to understand their relationship in the architecture. This chapter will highlight sensor devices from an electronics and system point of view. It is important to understand the principles of what is being measured, and why. One should ask, "What type of sensor or edge device should I consider for the problem I'm trying to solve?" An architect should consider aspects of cost, features, size, usable life, and precision when deploying an IoT solution. Additionally, the power and energy of edge devices are rarely addressed in IoT literature, but are critical to building reliable and long-lasting technology. The reader should leave this chapter with a high-level grasp of sensor technology and its constraints.
In this chapter, we will cover the following topics:
- Sensing devices from thermocouples to MEMS sensors to vision systems
- Energy generation systems
- Energy storage systems