Hands-On Robotics Programming with C++ E-Book

Dinesh Tavasalkar

• Herausgeber: Packt Publishing
• Sprache: Englisch

Seitenzahl: 233

Veröffentlichungsjahr: 2019

Beschreibung

C/C++ is one the legacy programming language for Robotics Programming. This book will help you understand and build complexly structured robots and implement various C/C++ programming libraries in it.

Leseprobe

Hands-On Robotics Programming with C++

Leverage Raspberry Pi 3 and C++ libraries to build intelligent robotics applications

Dinesh Tavasalkar

BIRMINGHAM - MUMBAI

Hands-On Robotics Programming with C++

Copyright © 2019 Packt Publishing

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing or its dealers and distributors, will be held liable for any damages caused or alleged to have been caused directly or indirectly by this book.

Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

Commissioning Editor: Vijin BorichaAcquisition Editor:Shrilekha InaniContent Development Editor:Abhijit SreedharanTechnical Editor:Mohd Riyan KhanCopy Editor:Safis EditingLanguage Support Editor: Mary McGowanProject Coordinator:Jagdish PrabhuProofreader: Safis EditingIndexer:Priyanka DhadkeGraphics:Tom ScariaProduction Coordinator: Jisha Chirayil

First published: March 2019

Production reference: 1290319

Published by Packt Publishing Ltd. Livery Place 35 Livery Street Birmingham B3 2PB, UK.

ISBN 978-1-78913-900-6

www.packtpub.com

This book is dedicated to my mentor, Asha Sundararajan. It was under her guidance that I began my career in robotics.

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Contributors

About the author

Dinesh Tavasalkar is a trainer and online instructor from India. He has trained more than 8,000+ students on topics related to robotics, Internet of Things, Arduino, Raspberry Pi, Android app development, augmented reality, and virtual reality. Dinesh's online courses have been undertaken by 25,000+ people on Udemy from more than 150+ countries. Some of his popular courses on Udemy include Robotics for beginners, Smartphone Control Robot using Arduino and Android, Build Augmented Reality apps using Unity and Vuforia, and Build Virtual Reality games for Google Cardboard using Unity. He also runs a YouTube channel called EngineersDream, where he teaches Android application development.

About the reviewers

Lentin Joseph is an author and robotics entrepreneur from India. He runs a robotics software company called Qbotics Labs in India. He has 8 years' experience in the robotics domain, primarily in ROS, OpenCV, and PCL. He has authored seven books on ROS, namely Learning Robotics Using Python, (First and Second Editions), Mastering ROS for Robotics Programming, (First and Second Editions), ROS Robotics Projects, Robot Operating System for Absolute Beginners, and ROS Programming. He did his master's in robotics in India and also did some research at Robotics Institute, CMU, USA.

Shahid Memon holds an MSc in autonomous robotics engineering and possesses a BSc in Computer Science. He has collaborated with colleagues on product feasibility studies and new product ideas to meet clients' needs and support companies' objectives. He has coordinated several product development projects and assisted in the design and testing phases. He is a strategic thinker with the ability to drive company goals and analyze research to impact product and business needs. He is an avid researcher of the latest trends within the technology industry and how these trends affects business. He is a proven leader with outstanding communication, interpersonal, project management, and supervisory skills.

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Table of Contents

Title Page

Copyright and Credits

Hands-On Robotics Programming with C++

Dedication

About Packt

Why subscribe?

Packt.com

Contributors

About the author

About the reviewers

Packt is searching for authors like you

Preface

Who this book is for

What this book covers

To get the most out of this book

Download the example code files

Download the color images

Conventions used

Get in touch

Reviews

Section 1: Getting Started with wiringPi on a Raspberry Pi

Introduction to the Raspberry Pi

Technical requirements

Software required

Hardware requirements

For Raspberry Pi 3B+ and Raspberry Pi Zero W

Additional hardware for Raspberry Pi 3B+

Additional hardware requirements for Raspberry Pi Zero W

Understanding the Raspberry Pi

The Raspberry Pi 3B+

The Raspberry Pi Zero W

Setting up a Raspberry Pi 3B+ as a desktop computer

Installing Raspbian OS on an SD card

Downloading and installing Etcher

Downloading the Raspbian Stretch image

Writing the Raspbian Stretch image to a microSD card

Setting up the Raspberry Pi 3B+

Connecting the Raspberry Pi 3B+ to the internet

Connecting the Raspberry Pi 3B+ to a laptop via Wi-Fi

Creating an SSH file on a microSD card

Connecting the Raspberry Pi 3B+ to a Wi-Fi network using PuTTY

Enabling the VNC server

Viewing the Raspberry Pi output on the VNC Viewer

Increase the VNC's screen resolution

Handling VNC and PuTTY errors

Setting up the Raspberry Pi Zero W as a desktop computer

Setting up the Raspberry Pi Zero W

Connecting the Raspberry Pi Zero W to a laptop via Wi-Fi

Connecting the Raspberry Pi Zero W to a Wi-Fi network using PuTTY

Enabling VNC Viewer for Raspberry Pi Zero W

Viewing Raspberry Pi Zero W output on VNC Viewer

Summary

Questions

Implementing Blink with wiringPi

Technical requirements

Installing the wiringPi library in the Raspberry Pi

Accessing Raspberry Pi GPIO pins via wiringPi

Making an LED blink

Wiring connections

The blinking program

Uploading the code to the Raspberry Pi

Smart light – working with digital sensor

The LDR sensor and the way it works

Wiring connection

Smart light program

Pulse Width Modulation using softPWM

How PWM works

The softPWM library

Making an LED blink with the softPWM library

Summary

Questions

Section 2: Raspberry Pi Robotics

Programming the Robot

Technical requirements

Choosing a robot chassis

Constructing and connecting the robot

Constructing the robot

Connecting the motor driver to the Raspberry Pi

What is a motor driver?

Wiring connections

Working with H-bridge

Moving the robot

Moving the robot backward

Stopping the robot

Different types of turns

Axial turns

Axial left turn

Axial right turn

Radial turn

Radial left turn

Radial right turn

Summary

Questions

Building an Obstacle-Avoiding Robot

Technical requirements

Using an ultrasonic sensor

How an ultrasonic sensor measures distances

The arithmetic equation for determining the time taken

Wiring the ultrasonic sensor to the Raspberry Pi

The HC-SR04 sensor program

Using an LCD

Wiring the 16x2 LCD to the Raspberry Pi

Programming the LCD

The LCD program

The LCD and the ultrasonic sensor program

What is the I2C protocol?

Wiring the I2C LCD and the Raspberry Pi

Programming the LCD with the I2C LCD module

The I2C LCD and the ultrasonic sensor program

Building an obstacle-avoiding robot

Wiring connections

Programming the obstacle-avoiding robot

Summary

Questions

Controlling a Robot Using a Laptop

Technical requirements

Installing the ncurses library

ncurses functions

Writing a HelloWorld program with ncurses

Compiling and running the program

Controlling LEDs and a buzzer using ncurses

Wiring connections

Writing the LEDBuzzer.cpp program

Controlling a rover using a laptop keyboard

Building a laptop-controlled rover program

Tracing a square path

Installing and setting up QT5

Setting up QT5

Controlling LEDs with GUI buttons

Creating a QT project

Dealing with errors

Controlling a rover using a laptop with QT5

Summary

Questions

Section 3: Face and Object Recognition Robot

Accessing the RPi Camera with OpenCV

Technical requirements

Installing OpenCV 4.0.0 on Raspberry Pi

Uninstalling Wolfram and LibreOffice

Updating your RPi

Installing the cmake, image, video, and gtk packages

Downloading and unzipping OpenCV 4.0 and its contribution repository

Installing Python

Compiling and installing OpenCV

Linking OpenCV to Python

Enabling and connecting the RPi camera to RPi

Connecting the RPi camera to RPi

Mounting the RPi camera on the robot

Capturing images and video with the RPi camera

Recording a video with the RPi camera

Installing the v4l2 driver

Reading an image using OpenCV

Summary

Questions

Building an Object-Following Robot with OpenCV

Technical requirements

Image processing with OpenCV

Important functions in OpenCV

Object recognition using OpenCV

Capturing the image

Finding the RGB pixel values

The object detection program

The OpenCV camera feed program

Building an object-following robot

Ball tracing using moments

Programming logic

The ball tracing program

Setting up the object-following robot

Object-following robot program

Summary

Questions

Face Detection and Tracking Using the Haar Classifier

Technical requirements

Face detection using the Haar cascade

Basic working of the Viola-Jones algorithm

Face-detection program

Detecting the eyes and smile

Detecting the eyes

Eye detection using haarcascade_eye

Eye detection using haarcascade_lefteye_2splits and haarcascade_righteye_2splits

Detecting the left eye

Detecting the right eye

Recognizing a smile

Programming logic for smile recognition

Face-tracking robot

Wiring connections

The programming logic

Using the white dot on the face triangle to move the robot

Summary

Questions

Section 4: Smartphone-Controlled Robot

Building a Voice-Controlled Robot

Technical requirements

An introduction to App Inventor

Creating a Talking Pi Android app

Designing the app

Programming the blocks

Main block

Intermediate block

Final block

The Talking Pi program

Importing and exporting the .aia file of the app

Creating a voice-controlled bot app

Designing the app

Adding and customizing the components

Programming the voice-controlled bot block

Pairing the Android smartphone and RPi via Bluetooth

Enabling the Bluetooth serial port

Developing the Bluetooth program for RPi

Socket programming

VoiceBot server program

Testing the code

Summary

Questions

Assessments

Chapter 1: Introduction to the Raspberry Pi

Chapter 2: Implementing Blink with wiringPi

Chapter 3: Programming the Robot

Chapter 4: Building an Obstacle-Avoiding Robot

Chapter 5: Controlling a Robot Using a Laptop

Chapter 6: Building an Object-Following Robot with OpenCV

Chapter 7: Accessing the RPi Camera with OpenCV

Chapter 8: Face Detection and Tracking Using the Haar Classifier

Chapter 9: Building a Voice-Controlled Robot

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Preface

C++ is one of the most popular legacy programming languages for robotics, and a combination of C++ and robotics hardware is used in many leading industries. This book will bridge the gap between Raspberry Pi and C/C++ programming and enable you to develop applications for Raspberry Pi. To follow along with the projects covered in the book, you can implement C programs in Raspberry Pi with the wiringPi library.

With this book, you’ll develop a fully functional car robot and write programs to move it in different directions. You’ll then create an obstacle-avoiding robot using an ultrasonic sensor. Furthermore, you’ll find out how to control the robot wirelessly using your PC/Mac. This book will also help you work with object detection and tracking using OpenCV, and guide you through exploring face detection techniques. Finally, you will create an Android app and control the robot wirelessly with an Android smartphone.

By the end of this book, you will have gained experience in developing a robot using Raspberry Pi and C/C++ programming.

Who this book is for

This book is designed for developers, programmers, and robotics enthusiasts interested in leveraging C++ to build exciting robotics applications. Some prior knowledge of C++ is necessary.

What this book covers

Chapter 1, Introduction to the Raspberry Pi, covers different modes of Raspberry Pi and GPIO pin configuration. Then, we will set up Raspberry Pi B+ and Raspberry Pi Zero and install the Raspbian OS on it. We will also learn how to connect a Raspberry Pi to a laptop wirelessly via a Wi-Fi network.

Chapter 2, Implementing Blink with wiringPi, covers the installation of the wiringPi library. In this chapter, we will understand the wiringPi pin connections for the Raspberry Pi. Then, we will write two C++ programs and will upload them onto our Raspberry Pi.

Chapter 3, Programming the Robot, covers the criteria for selecting a robot chassis. After that, we will construct our car, connect the motor driver to the Raspberry Pi, and understand the workings of an H-bridge circuit. Finally, we will write programs to move the robot forward, backward, left, and right.

Chapter 4, Building an Obstacle-Avoiding Robot, looks at how an ultrasonic sensor works, and we will write a program to measure distance values. Next, we will program the 16 x 2 LCD to read the ultrasonic distance value. We will also look at the I2C LCD, which takes the 16 LCD pin as an input and provides four pins as an output, thus simplifying the wiring connections. Finally, we will fit the ultrasonic sensor on our robot to create our obstacle-avoiding robot. This robot will move freely when there are no obstacles near it, and if it approaches an obstacle, it will avoid it by taking a turn.

Chapter 5, Controlling a Robot Using a Laptop, looks at two different techniques for controlling the robot using a laptop. In the first technique, we will use the ncurses library to take input from the keyboard to move the robot accordingly. In the second technique, we will use the QT Creator IDE to create GUI buttons, and then use these buttons to move the robot in different directions.

Chapter 6, Accessing Rpi Cam with OpenCV, focuses on the installation of OpenCV on the Raspberry Pi. You will also be introduced to the Raspberry Pi camera module and, after setting up the Pi camera, you will take pictures and record a short video clip using the Pi camera.

Chapter 7, Building an Object-Following Robot with OpenCV, covers some of the important functions inside OpenCV libraries. After that, we will put these functions to the test and attempt to recognize an object from an image. Then, we will learn how to read a video feed from the Pi camera, how to threshold a colored ball, and how to place a red dot on top of it. Finally, we will use the Pi camera and the ultrasonic sensor to detect the ball and follow it.

Chapter 8, Face Detection and Tracking Using Haar Classifier, uses the Haar face classifier to detect a face from a video feed and draw a rectangle around it. Next, we will detect eyes and a smile on the given face and create a circle surrounding the eyes and mouth. After using this knowledge of face and eye detection, we will first turn the LED on/off when the eyes and smile are detected. Next, by creating a white dot in the center of the face, we will make the robot follow the face.

Chapter 9, Building a Voice-Controlled Robot, starts with creating our first Android application, called Talking Pi, in which text written inside the textbox will be displayed in a label and also read out by the smartphone. We will then develop a voice-controlled Android app for the bot, which will recognize our voice and send text to the RPi via Bluetooth. After this, using the terminal window, we will pair the Android smartphone's Bluetooth with the RPi's Bluetooth. Finally, we will look at socket programming and write the VoiceBot program to establish a connection with the Android smartphone's Bluetooth in order to control the robot.

To get the most out of this book

To get through the code in this book, Raspberry Pi 3B+ or Raspberry Pi Zero board is required. The additional hardware and software is mentioned in the Technical requirements section of each chapter.

Download the example code files

You can download the example code files for this book from your account at www.packt.com. If you purchased this book elsewhere, you can visit www.packt.com/support and register to have the files emailed directly to you.

You can download the code files by following these steps:

Log in or register at

www.packt.com

.

Select the

SUPPORT

tab.

Click on

Code Downloads & Errata

.

Enter the name of the book in the

Search

box and follow the onscreen instructions.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

WinRAR/7-Zip for Windows

Zipeg/iZip/UnRarX for Mac

7-Zip/PeaZip for Linux

The code bundle for the book is also hosted on GitHub athttps://github.com/PacktPublishing/Hands-On-Robotics-Programming-with-Cpp. In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalog of books and videos available athttps://github.com/PacktPublishing/. Check them out!

Download the color images

We also provide a PDF file that has color images of the screenshots/diagrams used in this book. You can download it here: http://www.packtpub.com/sites/default/files/downloads/9781789139006_ColorImages.pdf.

Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "The code for taking axial and radial turns is added to the RobotMovement.cpp program."

A block of code is set as follows:

digitalWrite(0,HIGH); //PIN O & 2 will STOP the Left MotordigitalWrite(2,HIGH);digitalWrite(3,HIGH); //PIN 3 & 4 will STOP the Right MotordigitalWrite(4,HIGH);delay(3000);

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

digitalWrite(0,HIGH); //PIN O & 2 will STOP the Left MotordigitalWrite(2,HIGH);digitalWrite(3,HIGH); //PIN 3 & 4 will STOP the Right MotordigitalWrite(4,HIGH);

delay(3000);

Any command-line input or output is written as follows:

sudo nano /boot/config.txt

Bold: Indicates a new term, an important word, or words that you see on screen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Select the Remember password option and press OK."

Warnings or important notes appear like this.

Tips and tricks appear like this.

Get in touch

Feedback from our readers is always welcome.

General feedback: If you have questions about any aspect of this book, mention the book title in the subject of your message and email us at [email protected].

Errata: Although we have taken every care to ensure the accuracy of our content, mistakes do happen. If you have found a mistake in this book, we would be grateful if you would report this to us. Please visit www.packt.com/submit-errata, selecting your book, clicking on the Errata Submission Form link, and entering the details.

Piracy: If you come across any illegal copies of our works in any form on the internet, we would be grateful if you would provide us with the location address or website name. Please contact us at [email protected] with a link to the material.

If you are interested in becoming an author: If there is a topic that you have expertise in, and you are interested in either writing or contributing to a book, please visit authors.packtpub.com.

Reviews

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Section 1: Getting Started with wiringPi on a Raspberry Pi

In this section, you will first be introduced to the basics of Raspberry Pi and learn how to install the Raspbian OS on your Raspberry Pi. Next, you will work with the wiringPi library and execute your first C program on Raspberry Pi.

The following chapters are included in this section:

Chapter 1

,

Introduction to the Raspberry Pi

Chapter 2

,

Implementing Blink with wiringPi

Introduction to the Raspberry Pi

Initially developed with the idea of teaching and promoting basic computer programming in schools across the UK, the Raspberry Pi (RPi) became an instant hit. At a price of just $25 when it was initially released, it became so popular that it was, and still is, used by developers, hobbyists, and engineers all over the world.

In this chapter, you will explore the basic idea of a Raspberry Pi. You will then learn to install an operating system on the device. Finally, you will configure Wi-Fi on your Raspberry Pi and learn to connect it to a laptop over Wi-Fi and set up a remote desktop.

You will achieve each of these objectives through the following topics:

Understanding the Raspberry Pi

Installing Raspbian OS on a Raspberry Pi 3B+

Connecting a Raspberry Pi 3B+ to a laptop via Wi-Fi

Installing Raspbian OS on a Raspberry Pi Zero W

Connecting a Raspberry Pi Zero W to a laptop via Wi-Fi

Technical requirements

For this chapter, the following software and hardware will be required.

Software required

Please download the following software if you want to follow along with the instructions in this chapter:

Raspbian Stretch

: Raspbian Stretch is the

operating system

(

OS

) that we will write to a microSD card. Stretch is the OS that will run our Raspberry Pi. It can be downloaded from

https://www.raspberrypi.org/downloads/raspbian/

This OS is developed specifically for the Raspberry Pi.

Balena Etcher

: This software will format the microSD card and write the Raspbian Stretch image to the microSD card. It can be downloaded from

https://www.balena.io/etcher/

.

PuTTY

: We will use PuTTY to connect our Raspberry Pi to a Wi-Fi network and find the IP address that the Wi-Fi network assigns to it. It can be downloaded from

https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html

.

VNC Viewer

: With VNC Viewer, we will be able to view the Raspberry Pi display on our laptop. It can be downloaded from

https://www.realvnc.com/en/connect/download/viewer/

.

Bonjour

: This is generally used to connect printers to computers over Wi-Fi. It can be downloaded from

https://support.apple.com/kb/DL999?viewlocale=en_MY&locale=en_MY

.

Notepad++

: We will need Notepad++ to edit the code in the Raspbian Stretch image. It can be downloaded from

https://notepad-plus-plus.org/download/v7.5.9.html

.

Brackets:

Brackets allows those using macOS to edit the code in the Rapbian Stretch image. To download Brackets, go to

http://www.brackets.io/

.

The installation of all of this software is pretty straightforward. Keep the default settings checked, click on the Next button a few times, and then hit the Finish button once the installation is complete.

Hardware requirements

We need the following hardware to follow along with the instructions in this chapter.

For Raspberry Pi 3B+ and Raspberry Pi Zero W

If you use the Raspberry Pi 3B+ or the Raspberry Pi Zero W, you will need the following hardware:

Keyboard

Mouse

SD card—t

his should have a minimum of 8 GB of storage, but 32 GB is recommended

MicroSD card reader

Display unit—a computer monitor or TV that contains an HDMI port

HDMI cable

5V mobile charger or power bank. This will power the Raspberry Pi

Additional hardware for Raspberry Pi 3B+

The Raspberry Pi 3B+ needs the following additional hardware:

An Ethernet cable

Additional hardware requirements for Raspberry Pi Zero W

Since the Raspberry Pi Zero has a micro USB port and a Micro HDMI port, it needs the following additional hardware:

A USB hub

A micro USB B-to-USB connector (also known as

an

OTG connector

)

An HDMI-to-mini HDMI connector

Understanding the Raspberry Pi

Raspberry Pi is a credit card sized, Linux-based minicomputer invented by the Raspberry Pi Foundation in 2012. The first Raspberry Pi model was called the Raspberry Pi 1B, which was then followed by the Model A. Raspberry Pi boards were initially intended to promote computer science programs in schools. However, their inexpensive hardware and free, open source software, quickly made the Raspberry Pi popular among hackers and robotics developers.

The Raspberry Pi can be used as a fully functional computer. It can be used to perform tasks such as browsing the internet, playing games, and watching HD videos, as well as creating Excel and Word documents. But what really differentiates it from a normal computer is its programmable GPIO pins. The Raspberry Pi consists of 40 digital I/O GPIO pins that can be programmed.

In simple terms, the Raspberry Pi can be thought of as a combination of a minicomputer, as it can be used as a fully fledged computer, and an electronics hardware board, as it can be used to create electronics and robotics projects.

There are different Raspberry Pi models. In this book, we are going to be using the following two models:

The Raspberry Pi 3B+

The Raspberry Pi Zero W

The Raspberry Pi 3B+

The Raspberry Pi 3B+ was released in February 2018. Its specifications are shown in the following annotated photo:

The Raspberry Pi 3B+ specifications are as follows:

A Broadcom BCM2837 quad-core 1.4 GHz processor

1 GB RAM

A Broadcom VideoCore GPU

Bluetooth 4.2

Dual-band 2.4 GHz and 5 GHz Wi-Fi

An Ethernet port

Storage with a microSD card via a microSD slot

40 programmable GPIO pins

Four USB 2.0 ports

An HDMI port

A 3.5 mm audio jack

The

Camera Serial Interface

(

CSI