Smart Objects: The “Things” in IoT

IoT Part 1
Eduardo Marín
UCB 2025
With figures from: HANES, David. et al. (2017) IoT Fundamentals.
Smart objects
Smart objects are any physical objects that contain embedded technology
to sense and/or interact with their environment in a meaningful way by
being interconnected and enabling communication among themselves or
an external agent.

Sensors, Actuators, and Smart Objects: They are the fundamental

Naturally, a parallel can be drawn with humans and the use of their five senses
to learn about their surroundings. Human senses do not operate independently
in silos. Instead, they complement each other and compute together,
empowering the human brain to make intelligent decisions. The brain is the
ultimate decision maker, and it often uses several sources of sensory input to
validate an event and compensate for “incomplete” information.
Sensors
There are myriad different sensors available to measure virtually everything in the physical world. There are a number of ways to
group and cluster sensors into different categories, including the following:
Active or passive: Sensors can be categorized based on whether they produce an energy output and typically require an external
power supply (active) or whether they simply receive energy and typically require no external power supply (passive).
Invasive or non-invasive: Sensors can be categorized based on whether a sensor is part of the environment it is measuring
(invasive) or external to it (non-invasive).
Contact or no-contact: Sensors can be categorized based on whether they require physical contact with what they are measuring
(contact) or not (no-contact).
Absolute or relative: Sensors can be categorized based on whether they measure on an absolute scale (absolute) or based on a
difference with a fixed or variable reference value (relative).
Area of application: Sensors can be categorized based on the specific industry or vertical where they are being used.
How sensors measure: Sensors can be categorized based on the physical mechanism used to measure sensory input (for
example, thermoelectric, electrochemical, piezoresistive, optic, electric, fluid mechanic, photoelastic).
What sensors measure: Sensors can be categorized based on their applications or what physical variables they measure.
Sensors
Sensors
Actuators
Actuators receive some type of control signal (commonly an electric
signal or digital command) that triggers a physical effect, usually some
type of motion, force, and so on.
Actuators
Much like sensors, actuators also vary greatly in function, size, design, and so
on. Some common ways that they can be classified include the following:
Type of motion: Actuators can be classified based on the type of motion they
produce (for example, linear, rotary, one/two/three-axes).
Power: Actuators can be classified based on their power output (for example,
high power, low power, micro power)
Binary or continuous: Actuators can be classified based on the number of
stable-state outputs.
Area of application: Actuators can be classified based on the specific industry
or vertical where they are used.
Type of energy: Actuators can be classified based on their energy type.
Actuators
Smart objects
The definition of a smart object has been a bit nebulous because of the
different interpretations of the term by varying sources. To add to the
overall confusion, the term smart object, despite some semantic
differences, is often used interchangeably with terms such as smart
sensor, smart device, IoT device, intelligent device, thing, smart thing,
intelligent node, intelligent thing, ubiquitous thing, and intelligent
product. In order to clarify some of this confusion, a smart object, is a
device that has, at a minimum, the following four defining characteristics:
Processing unit, sensor(s) and/or actuator(s), communication device and
power source.
Smart Objects
Processing unit: A smart object has some type of processing unit for acquiring data, processing and analyzing sensing information received
by the sensor(s), coordinating control signals to any actuators, and controlling a variety of functions on the smart object, including the
communication and power systems. The specific type of processing unit that is used can vary greatly, depending on the specific processing
needs of different applications. The most common is a microcontroller because of its small form factor, flexibility, programming
simplicity, ubiquity, low power consumption, and low cost.

Sensor(s) and/or actuator(s): A smart object is capable of interacting with the physical world through sensors and actuators. In fact, a smart
object can contain one or multiple sensors and/or actuators, depending upon the application.

Communication device: The communication unit is responsible for connecting a smart object with other smart objects and the outside
world (via the network). Communication devices for smart objects can be either wired or wireless.

Power source: Smart objects have components that need to be powered. Interestingly, the most significant power consumption usually
comes from the communication unit of a smart object. As with the other three smart object building blocks, the power requirements also
vary greatly from application to application. Typically, smart objects are limited in power, are deployed for a very long time, and are not
easily accessible. This combination, especially when the smart object relies on battery power, implies that power efficiency, judicious
power management, sleep modes, ultra-low power consumption hardware, and so on are critical design elements. For long-term
deployments where smart objects are, for all practical purposes, inaccessible, power is commonly obtained from scavenger sources (solar,
piezoelectric, and so on) or is obtained in a hybridized manner, also tapping into infrastructure power.
Smart Objects
Trends in Smart Objects
Size is decreasing: There is a clear trend of ever-decreasing size. Some smart objects are so small they
are not even visible to the naked eye. This reduced size makes smart objects easier to embed in
everyday objects.
Power consumption is decreasing: The different hardware components of a smart object continually
consume less power. This is especially true for sensors, many of which are completely passive. Some
battery-powered sensors last 10 or more years without battery replacement.
Processing power is increasing: Processors are continually getting more powerful and smaller. This is a
key advancement for smart objects, as they become increasingly complex and connected.
Communication capabilities are improving: It’s no big surprise that wireless speeds are continually
increasing, but they are also increasing in range. IoT is driving the development of more and more
specialized communication protocols covering a greater diversity of use cases and environments.
Communication is being increasingly standardized: There is a strong push in the industry to develop
open standards for IoT communication protocols. In addition, there are more and more open source
efforts to advance IoT.
Sensor Networks
A sensor/actuator network (SANET), is a network of sensors that sense and measure their
environment and/or actuators that act on their environment. The sensors and/or actuators in
a SANET are capable of communicating and cooperating in a productive manner.

SANETs offer highly coordinated sensing and actuation capabilities. Smart homes are a type
of SANET that display this coordination between distributed sensors and actuators. For
example, smart homes can have temperature sensors that are strategically networked with
heating, ventilation, and air-conditioning (HVAC) actuators. When a sensor detects a
specified temperature, this can trigger an actuator to take action and heat or cool the home as
needed.

While such networks can theoretically be connected in a wired or wireless fashion, the fact
that SANETs are typically found in the “real world” means that they need an extreme level of
deployment flexibility.
Wireless Sensor Networks (WSNs)
Wireless sensor networks are made up of wirelessly connected smart objects, which are sometimes
referred to as motes. The fact that there is no infrastructure to consider with WSNs is surely a powerful
advantage for flexible deployments, but there are a variety of design constraints to consider with these
wirelessly connected smart objects.
Hierarchies of Smart Objects
The ability to aggregate similar sensor readings from sensor nodes that
are in close proximity to each other.