Raspberry Pi Robotic Projects: Work through a mix of amazing robotic projects using the Raspberry Pi Zero or the Raspberry Pi 3 , Third Edition

There are several R2D2 toys that can provide the basis for this project. They are available from online retailers. This project will use one that is inexpensive but also provides such interesting features as a top that turns and a wonderful place to put a webcam. It is the Imperial Toy R2D2 bubble machine. Here is a picture of the unit:

The unit can be purchased at websites such as Amazon, Toys R Us, and a number of other e-retailers. It is normally used as a bubble machine that uses a canister of soap to produce bubbles, but you'll take all of that capability out to make your R2D2 much more like the original robot.

The hardware is ready; now you can access all this functionality from the Raspberry Pi. First, install the library associated with the control board, found at http://www.monkmakes.com/rrb3/. Perform the following steps:

#!/usr/bin/python 
import time 
import RPi.GPIO as io 
from rrb3 import * 
 
io.setmode(io.BCM) 
 
forward_pin = 27 
backward_pin = 22 
led1 = 24 
led2 = 23 
 
def forward(): 
    io.output(forward_pin, True) 
    io.output(backward_pin, False) 
 
...

Now that your robot is mobile, it is time to allow your robot to speak and respond to voice commands as well. This will make your R2D2 more interactive. To do this, you'll need to add some hardware. This project requires a USB microphone and a speaker adapter. The Raspberry Pi has an audio output, but does not have an audio input, so you'll need the following three pieces of hardware:

Fortunately, these devices are very inexpensive and widely available.

Now, on to allowing the Raspberry Pi access to these devices. You can execute all of the following...

Sound is an important tool in our robotic toolkit, but you will want to do more than just play music. Let's make our robot speak. You're going to start by enabling eSpeak, an open source application that provides us with a computer voice. eSpeak is an open source voice generation application. To get this free functionality, download the eSpeak library by typing sudo apt-get install espeak in the prompt. The download may take a while, but the prompt will reappear when it is complete. Now, let's see if our Raspberry Pi has a voice. Type the espeak "hello" command. The speaker should emit a computer-voiced hello. If it does not, check the speakers and the volume level.

Now that we have a computer voice, you may want to customize it. eSpeak offers a fairly complete set of customization features, including a large number of languages, voices, and other options. To access these, you can type in the options at the command prompt. For example, type in espeak...

Now that your robot can speak, you'll want it to also obey voice commands. This section will show you how to add speech recognition to your robotic projects. This isn't nearly as simple as the speaking part, but thankfully, you have some significant help from the open source development community. You are going to download a set of capabilities named PocketSphinx, which will allow our project to listen to our commands.

The first step is downloading the PocketSphinx capabilities. Unfortunately, this is not quite as user friendly as the espeak process, so follow along carefully. There are two possible ways to do this. If you have a keyboard, mouse, and display connected, or want to connect through vncserver, you can do this graphically by performing the following steps:

Now that the system can both hear and speak, you'll want to provide the capability to respond to your speech and execute some commands based on the speech input. Next, you're going to configure the system to respond to simple commands.

In order to respond, you're going to edit the continuous.c code in the /home/pi/ pocketsphinx-0.8/src/programs directory. You could create our own C file, but this file is already set up in the makefile system and is an excellent starting spot. You can save a copy of the current file in continuous.c.old so that you can always get back to the starting program, if required. Then, you will need to edit the continuous.c file. It is very long and a bit complicated, but you are specifically looking for the section in the code, which is shown in the following screenshot. Look for the /* Exit if the first word spoken was GOODBYE */ comment line:

In this section of the code, the word has already been decoded and is held...

No self-respecting R2D2 robot would be complete without the ability to see. Fortunately, your R2D2 has just the right spot for a webcam. Once you remove the bubble blowing port, you have the perfect spot for a round webcam.

Here is a picture of a round webcam, which is available on amazon.com and other online retailers:

Here is a picture of the webcam mounted in the slot:

You now need to connect the USB camera to the USB port of the Raspberry Pi. To access the USB webcam directly on the Raspberry Pi, you can use a Linux program called guvcview. Install this by powering up the Raspberry Pi, logging in, and entering the sudo apt-get install guvcview command.

To try your USB camera, connect it and reboot your Raspberry Pi. To check if the Raspberry Pi has found your USB camera, go to the /dev directory and type ls. You should see something similar to the following screenshot:

Look for video0, as this is the entry for your webcam. If you see it, the system knows your...

Now that you have your camera connected, you can begin to access some amazing capabilities that have been provided by the open source community. The most popular of these for computer vision is OpenCV. To do this, you'll need to install OpenCV. There are several possible ways of doing this; I'm going to suggest the ones that I follow to install it on my system. Some of these packages may have already been installed based on earlier activities, but I'll document all the steps here. Once you have booted the system and opened a Terminal window, type the following commands in the given order:

Now, via vncserver, you can access a video feed and control your robot. Simply access vncserver, open two Terminal windows, and in one Terminal window run camera.py, while in the other Terminal window run r2d2Control.py, like this:

In this instance, there is a third window so that you can use aplay to play R2D2 WAV files that you have downloaded from the Internet. Now you can remotely pilot your R2D2 from a host computer or tablet. If you'd like to do it via a tablet or phone, you'll want to download an SSH app; there are several available from the different app stores. You can use your Wi-Fi settings to connect to the R2D2 access point. Then run the SSH app to access your R2D2 and start vncserver. Then you'll need a vncviewer app; again, there are several available, to access your R2D2 and run a similar configuration from your tablet or phone.

OpenCV is an amazing, powerful library of functions. You can do all sorts of incredible things with just a few lines...

You've completed your first project, your own R2D2. You can now move it around, program it to respond to voice commands, or run it remotely from a computer, tablet, or phone. Following in this theme, your next robot will look and act like WALL-E.