Assembling the Robot

This chapter will provide you with a variety of practical assembly guidelines about the mobile robot that the content of this book is based on. With a very practical approach in mind, we'll deep dive into the characteristics of GoPiGo3 and what makes it an ideal platform to learn robotics.

First, we will focus on the hardware and talk about the components that every robot is composed of including the mechanical parts and embedded system, sensor, and motors.

After completing the GoPiGo3 assembly section, you will be acquiring manual skills so that you can start manipulating typical components in robotics. You will also be driven to adopt a systematic approach of applying partial verification tests while assembling your robot, also known as unit tests.

After introducing the GoPiGo3 robot in the first section of this chapter, we will explain these concepts...

Understanding the GoPiGo3 robot

GoPiGo3 is a Raspberry Pi-based robot car manufactured by Dexter Industries. It is intended to be used as an educational kit for learning about both robotics and programming, two complementary perspectives that clearly show the transversal knowledge you should acquire to become a robotics engineer. We'll explain what this means by letting Nicole Parrot, Director of Engineering at Modular Robotics, explain it in her own words:

"The GoPiGo originated from a Kickstarter campaign in early 2014 when the Raspberry Pi was still somewhat new. The first users were hobbyists, but soon teachers and coding club volunteers were sharing their GoPiGo with their students. This lead to various changes being made to the board to make a classroom-ready robot. It's robust, it has a full list of features, and it's still based on the Raspberry Pi...

Getting familiar with the embedded hardware

Do you remember which hardware is for what? The GoPiGo3 board is for interfacing with sensors and actuators, while Raspberry Pi is used for computing tasks. We will cover these topics in detail here.

The GoPiGo3 board

This customized board (https://www.dexterindustries.com/GoPiGo/learning/hardware-port-description/) provides the general features that are expected from a controller:

• Real-time communication with sensors and actuators.
• Interface input/output (I/O) through a serial peripheral interface (SPI) that feeds the data from the sensors to the Raspberry Pi and may also receive commands for the actuators (also from the Raspberry Pi, after running the logic in its CPU for every...

Deep diving into the electromechanics

As explained in GoPiGo's official documentation (https://www.dexterindustries.com/GoPiGo/learning/technical-specifications-for-the-gopigo-raspberry-pi-robotics-kit/), the specifications of the GoPiGo3 robot are as follows:

• Operating voltage: 7V-12V
• External interfaces:
  • I2C ports: Two Grove ports connected to the Raspberry Pi I2C bus through a level-conversion chip
  • Serial ports: One Grove port connected to the serial pins on the Raspberry Pi through a level-conversion chip
  • Analog digital ports: Two Grove ports connected to the GoPiGo3 microcontroller
• Encoders: Two magnetic encoders with six pulse counts per rotation (with 120:1 gear reduction for a total of 720 pulses per wheel rotation)
• Wheels diameter: 66.5 mm
• Distance between wheels: 117 mm
• More: Design information is available at the official GitHub repository (https://github.com...

Putting it all together

Now that you are familiar with the hardware, it is time to put everything together, connect it, and run a quick test to check that GoPiGo3 works properly. The assembly process is very well documented in a step-by-step guide in the official documentation, along with plenty of figures and photos; you can find this documentation at https://www.dexterindustries.com/GoPiGo/get-started-with-the-gopigo3-raspberry-pi-robot/1-assemble-gopigo3/.

Alternatively, you can use the Workbench training environment at https://edu.workbencheducation.com/ and register a personal account for free to go through the same assembly process while registering your progress. If you do, then follow the two assembly stages that are covered in the official documentation from the manufacturer:

• GoPiGo3 assembly stage 1: https://edu.workbencheducation.com/cwists/preview/26659-build-your...

Quick hardware test

To perform a quick test and focus on the hardware at hand, we will use DexterOS, the Raspbian-based distro created by Dexter Industries to allow the user to get started quickly. Details of the operating system are provided at https://www.dexterindustries.com/dexteros/. Instead of having to deal with a full Linux desktop, Dexter Industries has simplified the interface by providing a simple web environment.

You can access it by connecting to the Wi-Fi access point called GoPiGo (a password won't be needed). This way, you will be connected directly to the robot with your laptop. Before installing it, let's review the resources we have available.

Resources

There are at least three sites/repositories...

Summary

In this chapter, we familiarized ourselves with the GoPiGo3 hardware by learning about the physical principles of the sensors and the motor the kit has. We checked that they worked properly by running some quick tests so that we can start programming tasks.

In the next chapter, we will learn how to program GoPiGo3 with Python while we execute some unit tests for each of its main components: the servomotors, distance sensor, line follower, IMU, and the Pi Camera.

Questions

1. Is it mandatory for a robot to have a computer such as Raspberry Pi?

A) Yes, because the computer powers the controller board.
B) No, because the computer is only needed for visualizing the software code on a screen. It may work alone with the controller if a program has been flashed to it.
C) Not really; you could write a small program that controls the robot and flash it to the chip of the controller. Every time you power the robot, it will execute the program in an endless loop.

2. What kind of radiation is emitted by the distance sensor of GoPiGo3?

A) Laser
B) Infrared
C) Ultrasound

3. Why can't you see the light being emitted by the line-follower sensor?

A) Because the sensor has to be previously activated with a software command
B) It does not emit light but a magnetic field
C) It does not emit anything in the visible range of light

4. What is the purpose of the...

Further reading

You can find out more about the features of GoPiGo3 by reading the extensive official documentation provided by the manufacturer:

• Dexter Industries GoPiGo3 documentation: https://gopigo3.readthedocs.io
• Dexter Industries DI-Sensors documentation: https://di-sensors.readthedocs.io
• Pi Camera documentation: https://picamera.readthedocs.io/