For this chapter, you will require basic drawing materials, such as a pen and paper. While software such as Draw.io, Dia, Pencil, Inkscape, or Visio could be used, a back-of-an envelope sketch of a block diagram is a great start to robot planning. Most of my robots start that way.

We can start by looking at a robot as a physical system. However, instead of looking at it all joined together, you can see how a typical hobby rover looks when totally disassembled in the following diagram:

A robot can also be visualized as a block diagram of connected parts. Block diagrams use simple shapes to show a rough idea of how things may be connected. Refer to the following diagram:

The preceding diagram is a block diagram. This is not a formal notation; the important factor is that you can clearly see the blocks of functionality you intend in the hardware, with the high-level flow of data between them. This can be a sketch on the back of a bit of scrap paper. The key I've created is off the top of my head, but it must be something that helps distinguish sensors, outputs, and...

A motor is an output device that results in rotation when power is applied. An actuator is an output device, which is any device that creates movements from an electrical signal. Examples of actuators are solenoids, valves, and pneumatic rams. Motors are a subset of actuators too.

A sensor is a device that provides input to a robot, allowing it to sense its environment. There are more sensor types than a single book can list, so we'll keep to the commonly available and fun-to-use ones.

I've laid out some of the different kinds of motors, all of which are used in robotics. Let's take a look at what each one does, and how we might use them for different...

At the center of the robot block diagram are the controllers. Robots usually have a main controller, a computer of some kind. They may also have some secondary controllers, and some more unusual robots have many controllers. Sticking with the conventional main controller, this is the system that your code will run. It is the part that connects all the other components together and forms the basis of their interactions.

IO pins are used for input and output from the controller; they give the controller its ability to connect to real-world sensors and motors.

The number of IO pins on the controller can be a major limiting factor in what you can connect to a robot without using secondary controllers...

You've now briefly seen some components you might use in a robot, and you've encountered a block diagram to put them together. This is where you may start taking the next step and thinking further about how things will be connected, and how the code you write for them will be structured. Code is easier to reason about when taken as logical blocks instead of one large lump. Arranging code in ways that are similar to a hardware functionality diagram will help navigate your way around as it becomes more complicated.

So, let's return to the robot block diagram seen before.

This diagram has three sensors and two outputs. Throughout this book, you will see diagrams like this, and then be adding new modules along with new bits of code to deal with them. Each component (sensor, output, and controller board) may need a few bits of code...

Let's put all of this to use, and plan the robot that we are making in this book. Although as we go through chapters we will be adding new components each time, having an overall map in our minds as we go helps us to see where we are. It is quite exciting to start to picture all the things a robot will do. Let's start with a list of what our robot will do and be:

• It will have wheels and be able to drive around the floor
• It will have a Raspberry Pi 3 controller
• It will have a motor controller for the wheels
• It will be able to follow lines with a pair of line following sensors

• It will be able to indicate its status with a set of multicolored LEDs
• The robot will use a pair of servo motors for a pan and tilt mechanism
• It will be able to avoid walls and navigate around obstacles with either ultrasonic or laser distance sensors
• It will have an encoder...

1. What is an IO pin?
2. What tools do you need to make a block diagram?
3. What are the drawbacks of the laser ranging sensor versus the ultrasonic distance sensor?
4. What type of system is a microphone?
5. What kind of IO pin is correct for measuring varying resistance?
6. What type of IO pin would be suitable for detecting an on/off signal?

• Raspberry Pi Sensors by Rushi Gajjar: Integrate sensors into your Raspberry Pi projects and let your powerful microcomputer interact with the physical world.

• Make Sensors: A Hands-On Primer for Monitoring the Real World with Arduino and Raspberry Pi by Tero Karvinen, Kimmo Karvinen, and Ville Valtokari. Learn to use sensors to connect a Raspberry Pi or Arduino controller with the real world.

• Make Electronics: Learning by Discovery by Charles Platt: This is useful if you want to find out more about electronic components and dive deeper into individual components.