A robot is a machine that makes autonomous decisions based on input from sensors. A software agent is a program that automatically processes input and produces output. Perhaps a robot is best described as an autonomous software agent with sensors and moving outputs, or it could be described as an electromechanical platform with software running on it. Either way, a robot requires electronics, mechanical parts, and code.

The word robot conjures up images of fantastic sci-fi creations, devices with legendary strength and intelligence. These often follow the human body plan, making them an android, a human-like robot. They're often given a personality and behave like a person who is, in some simple way, naïve:

Figure 1.1 – Science fiction and real-world robots. Images used are from the public domain OpenClipArt library

The word robot comes from science fiction (also known as sci-fi). The word is derived from the Czech word for slave and was first used in the 1921 Karel Capek play, Rossum's Universal Robots. The science fiction author Isaac Asimov coined the word robotics as he explored intelligent robot behavior.

Most real robots in our homes and industries are not cutting-edge and eye-catching. Most do not stand on two legs, or indeed any legs at all. Some are on wheels, and some are not mobile but still have moving parts and sensors.

Robots such as modern washing machines, autonomous vacuum cleaners, fully self-regulating boilers, and air sampling fans have infiltrated our homes and are part of everyday life. They aren't threatening and have become just another machine around us. The 3D printer, robot arm, and learning toys are a bit more exciting, though:

Figure 1.2 – The robot, simplified and deconstructed

At their core, robots can all be simplified down to outputs such as a motor, inputs such as a sensor, and a controller for processing or running code. So, a basic robot would look something like this:

• It has inputs and sensors to measure and sample properties of its environment.
• It has outputs such as motors, lights, sounds, valves, or heaters to alter its environment.
• It uses data from its inputs to make autonomous decisions about how it controls its outputs.

Now, we will go ahead and look at some advanced robots in the next section.

Now that you have an overview of robots in general, I'll introduce some specific examples that represent the most remarkable robots around, and what they are capable of. Except for the Mars robots, human and animal forms have been favored by these robot makers for their adaptability, contrasting with robots designed for industrial use and intended for single repeated use.

Figure 1.3 shows the similarities between these robots and humans/animals:

Figure 1.3 – A selection of human and animal-like robots. [Image credits: Image 1: This image can be found at https://commons.wikimedia.org/wiki/File:Cog,_1993-2004,_view_2_-_MIT_Museum_-_DSC03737.JPG, and is in the public domain; Image 2: This image can be found at https://commons.wikimedia.org/wiki/File:Honda_ASIMO_(ver._2011)_2011_Tokyo_Motor_Show.jpg, by Morio, under CC BY-SA 3.0, at https://creativecommons.org/licenses/by-sa/3.0/deed.en; Image 3: This image can be found at https://commons.wikimedia.org/wiki/File:Nao_Robot_(Robocup_2016).jpg and is in the public domain; Image 4: This image can be found at https://commons.wikimedia.org/wiki/File:Atlas_from_boston_dynamics.jpg, by https://www.kansascity.com/news/business/technology/917xpi/picture62197987/ALTERNATES/FREE_640/atlas%20from%20boston%20dynamics, under CC BY-SA 4.0, at https://creativecommons.org/licenses/by-sa/4.0/deed.en; Image 5: This image can be found at https://commons.wikimedia.org/wiki/Commons:Licensing#Material_in_the_public_domain and is in the public domain

What these robots have in common is that they try to emulate humans and animals in the following ways:

1. Robot 1 is Cog from the Massachusetts Institute of Technology. Cog was an attempt to be human-like in its movements and sensors.
2. Robot 2 is the Honda ASIMO, which walks and talks a little like a human. ASIMO's two cameras perform object avoidance, as well as gestures and face recognition, and have a laser distance sensor to sense the floor. It follows marks on the floor with infrared sensors. ASIMO accepts voice commands in English and Japanese.
3. Robot 3 is the Nao robot from Softbank Robotics. This cute 58 cm tall robot was designed as a learning and play robot for users to program. It has sensors to detect its motion, including if it is falling, and ultrasonic distance sensors to avoid bumps. Nao uses speakers and a microphone for voice processing. It has multiple cameras to perform similar feats to the ASIMO.
4. Robot 4 is Atlas from Boston Dynamics. This robot is fast on two legs and has natural-looking movement. It has a laser radar (LIDAR) array, which it uses to sense what is around it so as to plan its movement and avoid collisions.
5. Robot 5 is the Boston Dynamics BigDog, a four-legged robot, or quadruped. It can walk and run. It's one of the most stable four-legged robots, staying upright when being pushed, shoved, and walking in icy conditions.

You'll add some features like these in the robot you'll build. We'll use distance sensors to avoid obstacles, using ultrasonic sensors in the same way as Nao, and discussing laser distance sensors like ASIMO. We'll explore a camera for visual processing, line sensors to follow marks on the floor, and voice processing to work with spoken commands. We'll build a pan and tilt mechanism for a camera like the head of Cog.

The Mars rovers

The Mars rover robots are designed to work on a different planet, where there is no chance of human intervention if it breaks. They are robust by design. Updated software can only be sent to a Mars rover via a remote link as it is not practical to send up a person with a screen and keyboard. The Mars rover is headless by design:

Figure 1.4 – NASA's Curiosity rover at Glen Etive, Mars (Image Credit: NASA/JPL-Caltech/MSSS; https://mars.nasa.gov/resources/24670/curiosity-at-glen-etive/?site=msl)

Mars rovers depend on wheels instead of legs, since stabilizing a robot on wheels is far simpler than doing it for one that uses legs, and there is less that can go wrong. Each wheel on the Mars rovers has its own motor. The wheels are arranged to provide maximum grip and stability to tackle Mars's rocky terrain and lower gravity.

The Curiosity rover was deposited on Mars with its sensitive camera folded up. After landing, the camera was unfolded and positioned with servo motors. The camera is pointed using a pan and tilt mechanism. It needs to take in as much of the Mars landscape as it can, sending back footage and pictures to NASA for analysis.

Like the Mars robots, the robot you'll build in this book uses motor-driven wheels. Our robot is also designed to run without a keyboard and mouse, being headless by design. As we expand the capabilities of our robot, we'll also use servo motors to drive a pan and tilt mechanism.

Many robots have already infiltrated our homes. They are overlooked as robots because, at first glance, they appear ordinary and mundane. However, they are more sophisticated than they appear.

The washing machine

Let's start with the washing machine. It is used every day in some homes, with a constant stream of clothes to wash, spin, and dry. But how is this a robot?

Figure 1.5 – Components of a washing machine

Figure 1.5 shows a washing machine as a block diagram. There's a central controller connected to the display with controls to select a program. The lines going out of the controller are outputs. The connections coming into the controller are data from sensors. The dashed lines from outputs to the sensors show a closed loop of output actions in the real world, causing sensor changes. This is feedback, an essential concept in robotics.

The washing machine uses the display and buttons to let the user choose the settings and see the status. After the start button is pressed, the controller checks the door sensor and will sensibly refuse to start if the door is open. Once the door is closed, and the start button is pressed, it will output to lock the door. After this, it uses heaters, valves, and pumps to fill the drum with heated water, using sensor feedback to regulate the water level and temperature.

Each process could be represented by a set of statements like these, which simultaneously fill the drum and keep it heated:

start water pump
turn on the water heater
while water is not filled and water is not hot enough:
  if water filled then
    stop water pump
  if the water is hot enough then
    turn off heater
  else
    turn on the water heater

Note the else there, which is in case the water temperature drops below the correct temperature slightly. The washing machine then starts the drum spinning sequence – slow turns, fast spins, sensing the speed to meet the criteria. It will drain the drum, spin the clothes dry, release the door lock, and stop.

This washing machine is, in every respect, a robot. A washing machine has sensors and outputs to affect its environment. Processing allows it to follow a program and use sensors with feedback to reach and maintain conditions. A washing machine repair person may be more of a roboticist than I.

Other household robots

A gas central heating boiler has sensors, pumps, and valves. The boiler uses feedback mechanisms to maintain the temperature of the house, water flow through heating, gas flow, and ensuring that the pilot light stays lit. The boiler is automatic and has many robot-like features, but it is stationary and could not readily be adapted to other purposes. The same could be said for other home appliances such as smart fans and printers.

Smart fans use sensors to detect room temperature, humidity, and air quality, and then output through the fan speed and heating elements.

Other machines in the home, like a microwave, for example, have only timer-based operation, they do not make decisions, and are too simple to be regarded as robots.

Perhaps the most obvious home robot is a robot vacuum cleaner, as shown in Figure 1.6:

Figure 1.6 – A robotic vacuum cleaner – PicaBot (Image credit: Handitec [Public Domain - https://commons.wikimedia.org/wiki/File:PicaBot.jpg])

This wheeled mobile robot is like the one we will build here, but prettier. They are packed with sensors to detect walls, bag levels, and barrier zones, and avoid collisions. They most represent the type of robot we are looking at. This robot is autonomous, mobile, and could be reprogrammed to different behaviors.

As we build our robot, we will explore how to use its sensors to detect things and react to them, forming the same feedback loops we saw in the washing machine.

Another place where robots are commonly seen is in industry. The first useful robots were used in factories, and have been there for a long time.

Robot arms

Robot arms range from tiny delicate robots for turning eggs, to colossal monsters moving shipping containers. Robot arms tend to use stepper and servo motors. We will look at servo motors in the pan and tilt mechanism used in this book. Most industrial robot arms (for example, ABB welding robots) follow a predetermined pattern of moves, and do not possess any decision making. However, for a more sensor-based and smart system, take a look at the impressive Baxter from Rethink Robotics in Figure 1.7. Baxter is a collaborative robot designed to work alongside humans:

Figure 1.7 – The Rethink Robotics Baxter Robot (Image credit: Baxter at Innorobo by © Xavier Caré / Wikimedia Commons [CC-BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)])

Many robot arms are unsafe to work next to and could result in accidents, requiring cages or warning markings around them. Not so with Baxter; it can sense a human and work around or pause for safety. In the preceding image, these sensors are seen around the head. The arm sensors and soft joints also allow Baxter to sense and react to collisions.

Baxter has a training and repeat mechanism for workers to adapt it to a task. It uses sensors to detect joint positions when being trained or playing back motions. Our robot will use encoder sensors to precisely control wheel movements.

Warehouse robots

Another common type of robot used in industry is those that move items around a factory floor or warehouse:

Figure 1.8 – Warehouse robot systems: Stingray system by TGWmechanics [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], and Intellicart by Mukeshhrs [public domain]

Figure 1.8 picture 1 shows robotic crane systems for shifting pallets in storage complexes. They receive instructions to move goods within shelving systems.

Smaller item-moving robots, like Intellicart in Figure 1.8 picture 2, employ line sensors, by following lines on the floor, magnetically sensing wires underneath the floor, or by following marker beacons like ASIMO. Our robot will follow lines such as these. These line-following carts frequently use wheels because these are simple to maintain and can form stable platforms.