Creating a New VirtualBox Virtual Machine

Now that we have installed Oracle’s VirtualBox, run the program by double-clicking on its icon.

1. 1.

   After it starts, you will see an area on the window that looks like Figure 3-4. To create a new machine, i.e., one that has not been installed before, click on New. If you do not see this ribbon bar, then you can access it from the Tools ➤ New toolbar.

    

A screenshot of buttons labeled preferences, import, export, new, and add. Text below it reads welcome to Virtualbox!

1. 2.

   Fill out the installation form like in Figure 3-5. Click Next. This does not install the operating system; it is a placeholder for later.

    

A screenshot of Oracle setup wizard window for filling name, machine folder, type, and version. Next button is highlighted at the bottom.

1. 3.

   Next, we allocate memory for our development system. The default is 1024 MB, but we will allocate at least 2048 MB (Figure 3-6). You may allocate more, but 2048 MB is enough.

    

A screenshot of Oracle setup wizard window for selecting memory size. Next button is highlighted at the bottom.

1. 4.

   To create the virtual disk on the physical hard disk, accept the default settings shown in Figure 3-7. Since we do not have an existing drive, we have to create a new drive.

    

A screenshot of Oracle setup wizard window for check-in options for hard disk. Create a virtual hard disk now option is checked-in and create button is highlighted at the bottom.

1. 5.

   Accept the default setting for the virtual hard drive type shown in Figure 3-8. We chose VDI because it is optimized for VirtualBox.

    

A screenshot of Oracle setup wizard window for check-in options for hard disk file type. V D I option is checked-in and next button is highlighted at the bottom.

1. 6.

   Accept the default setting for the type of physical disk storage type shown in Figure 3-9. We chose dynamic, so the size can grow and shrink automatically.

    

A screenshot of Oracle setup wizard window for check-in options for storage on physical hard disk. Dynamically allocated option is checked-in and next button is highlighted at the bottom.

1. 7.

   Finally, set the location and maximum size your virtual disk can hold (Figure 3-10). The default location is derived from your original disk name, and the default size is okay for our little project. Click Create.

    

A screenshot of Oracle setup wizard window for file location and size. Size is set at 10 G B and create button is highlighted at the bottom.

1. 8.

   You should now have a virtual machine installed, as shown by the orange box in Figure 3-11.

    

A screenshot of Oracle V M Virtual box manager. A bar on the left lists melodic Linux running and Ubuntu R O S power off.

What we have just done is create an empty disk that we will next install in our Ubuntu Linux operating system.

Updating Ubuntu Linux 20.04.4

Now that we have installed Ubuntu, to start the operating system, click on the Start button (Figure 3-27). You may be prompted for additional installation information; just reply “yes” to the default choices. It will also ask you to log in. After the operating system launches, you should have a window that looks like Figure 3-28. (The VirtualBox menu and bottom of the screen commands will be cropped off of future images.) We are now ready to install ROS through terminal commands.

A screenshot of Ubuntu home screen.

In Figure 3-28, the desktop includes system application icons on the left, a trashcan to delete items, a header bar that has the day and time, and four icons in the upper right-hand corner (network, sound, battery, and down arrow). We will discuss these as necessary.

1. 1.

   To start a terminal window, right-click on the desktop background, being sure to avoid icons (Figure 3-29). Click on the Open in Terminal menu choice.

    

A screenshot of Ubuntu home screen with open in terminal option selected on the right-click access menu.

1. 2.

   On a freshly installed Linux system, your terminal will be full screen (Figure 3-30). Later on, we will run multiple terminals at the same time, so let’s make the terminal “windowed” by clicking on the □ in the upper-right corner of the terminal, as indicated by the orange arrow.

    

A screenshot of Ubuntu terminal window with an arrow pointing at a square button.

1. 3.

   Now we have a terminal window on our desktop (Figure 3-31). The installation of ROS will be done through this terminal window using commands. We are not going to fully explain the commands, since it is beyond the scope of this book, but simple internet research should suffice if you want to investigate further.

    

A screenshot of Ubuntu terminal window on the home screen.

to upgrade your operating system files to the latest versions.

After it stops, you will now have the newest version of Ubuntu Linux 20.04.4 installed (Figure 3-33). As an aside, for this chapter, from now on, we will show commands in the terminal in an orange rectangle, not in text prose.

A screenshot of command window with two highlighted text that reads sudo apt-get update and sudo apt-get upgrade.

A screenshot of command window with a list of commands.

We have now updated our Ubuntu Linux system to the latest version. Next, we need to set up Ubuntu to allow external libraries (ROS, etc.) These libraries come from external repositories.

Configuring Ubuntu Repositories

To download repositories from external third-party software sites, such as ROS.org, we need to tell the system about these sites. To do this, click on the System Settings icon on the left side of your desktop (Figure 3-34).

A screenshot of Ubuntu system settings icon.

Up pop several icons. Click the Software Updates icon on the desktop (Figure 3-35).

A screenshot of Ubuntu software update icon.

Next, we select the Settings option as in Figure 3-36. The Settings option defines the software to be installed or upgraded, including third-party software, such as ROS.

A screenshot of Ubuntu software update dialog box with highlighted settings button.

On the new popup window, select the Ubuntu Software tab and set the checkboxes shown in Figure 3-37. Once those selections have been made, then please click Close. These selections approve the download of third-party software.

A screenshot of highlighted Ubuntu software tab on a dialog box titled software and updates.

Installing ROSINSTALL

Be very careful about the spaces and dashes in the previous command. If you get an error, verify every dash and space.

Starting ROS for the Very First Time

Adding the ROS Path

Every time you want to use ROS, you need to tell the operating system where to look for the ROS commands, i.e., add the ROS path to the global path. Since we have to do this every time we want to use ROS, we will create a bash script. In a text editor (Gedit), create a file called STARTrosconfig.sh with the included lines (Figure 3-43).

A screenshot of command window.

Next, save the file to the /home/ros directory. This will be reflected in the Gedit user interface by the small orange box, as in Figure 3-44. Open a new terminal. Using Figure 3-38 as our guide, we are going to make STARTrosconfig.sh executable. Orange boxes are commands you will type in, and green boxes are outputs you should observe. After you type in your first two commands, observe that STARTrosconfig.sh is white, which means it is not executable. The next command (ls -la STARTrosconfig.sh) is optional and looks at the details for the file. You should note that the file can be read (r) and written (w), but not executed (-). To change this, you must issue the change mode command (chmod +rwx STARTrosconfig.sh). To verify the change occurred, ls -la STARTrosconfig.sh will show rwx and a green name. Success!

A screenshot of command window with many highlighted commands.

Every time you want to work with ROS, open a terminal and type source STARTrosconfig.sh. This adds the ROS path to the system (Figure 3-45). To verify the ROS variables were installed correctly, type env | grep ROS_*. This command looks at the environment variables (env) and selects only those variables starting with “ROS_”.

A screenshot of command window.

Creating a ROS Catkin Workspace

The catkin_ws workspace has now been sourced as the main workspace directory for developing applications within the ROS environment. If we did not obtain the ROS package path directory output as expected, please consult debugging issues within the ROS.org Community website for further information.

Final Checks for Noetic ROS

The following shell text command will determine if the correct version of ROS has indeed been installed and is operational:

If the output is Noetic, then you have completely succeeded in obtaining a fully operational ROS environment. Congratulations.

Noetic ROS Architecture

With the successful installation of Noetic ROS, we will introduce its architecture. The ROS architecture was designed to operate with robots of all types (rovers, drones, planes, boats, submarines, etc.). As such, the ROS framework was designed to handle multiple components or nodes in a robot. A node is a sensor, motor, controller, etc. In other words, it is a piece of hardware that performs a function for the robot. ROS refers to a “program node” as the software necessary to control the hardware. The primary node is known as the central master node.

The ROS architecture handles the communication between nodes. For example, if the central master node receives data from a distance sensor node indicating an object is in our path, then the master node might send move commands to a driver node to change the robot’s directions (Figure 3-46). The ROS architecture helps us to manage the increasing complexity of a robot system as more features, sensors, and actuators are added.

A schematic of an oval labeled master connected to line detector via surface, driver via velocity, controller via distance, surface, and velocity, and distance sensor via distance.

Figure 3-46 shows five nodes: the master node and four system nodes. When a system node starts, it sends information to the master comprising the type of data that the node can send and receive. The nodes that send data to the master node are called publisher nodes. For example, the Distance Sensor and Line Detector nodes are publisher nodes, since they send data (distance to target and surface information, respectfully) to the master node. The nodes that receive data from the master node are called subscriber nodes. So the Driver node is a subscriber node since it receives velocity data from the master node. The Controller node is both a publisher and a subscriber node.

The Controller node will be hosting the deep learning and cognitive deep learning routines developed in later chapters. These deep learning routines will send and receive messages to and from the ROS master node. The master node will reroute that message to their intended nodes, such as a message to the Driver node to control the speed.

Simple “Hello World” ROS Test

Now that we have described the basic ROS architecture, let’s determine if our installation of ROS was successful by executing simple ROS tutorial scripts. This script will simply have two ROS nodes: a talker (publisher) and a listener (subscriber). If we look at Figure 3-47, we see three nodes. First, when the listener is created, it tells the master node that it wants to listen to the talker (subscribes). Next, when the talker is created it registers with the master node. Finally, the talker generates (publishes) a message; this means it sends the message to the master. This causes the master node to send the message to all nodes listening to the talker, which means the message is sent to the listener.

A schematic of an oval labeled R O S master with a box below it labeled hello world. Two ovals on the bottom left and bottom right labeled talker node and listener node point at R O S master via arrows labeled 1 and 2, respectively. An arrow from talker node points at hello world which point at listener node.

If you have made it this far, congratulations, you have successfully installed VirtualBox, Ubuntu Linux, and Noetic ROS. (Do not shut down the nodes, as we will use them in the next section.) Next, we visit two components that come with ROS: RQT Graph and Gazebo Robot Simulator. (We will talk about Rviz and TensorFlow when we use them.)

ROS RQT Graph

The RQT Graph is an important visualization and debugging tool. This graphing tool will be used to debug running nodes and inspect the communication between them. We will use RQT Graph to inspect our two nodes that are running from the previous section. In a new terminal, enter the following command, and you will get something like Figure 3-48:

$ rosrun rqt_graph rqt_graph

A screenshot of R Q T graph tool window. A oval on the left reads talker and an oval on the right reads listener with a rightward arrow in between labeled chatter.

The ROS command rosrun rqt_graph rqt_graph graphically displays all active publisher and subscriber nodes in an RQT Graph window. The interpretation of Figure 3-43 is that /talker is sending a message to /listener. Notice that the ROS master node is left out. The default message pipeline name is /chatter.

ROS Gazebo

Gazebo is a graphical simulation tool used to visualize any virtual world you create. The virtual world can contain objects, robots, buildings, obstacles, etc. You define them in terms Gazebo understands, and it will be simulated in a Gazebo window.

Gazebo is a standalone program that needs to be tied to the ROS system and world definition. This means we will “launch” the program from “within” ROS using the roslaunch command. Briefly, the ROS way of doing things: rosrun and roslaunch. The command rosrun launches a (Python) script to run an object’s script by itself (or a limited number of other objects). In contrast, roslaunch loads and executes all objects (and associated scripts) in a world environment, where each object can interact with the other objects.

The roslaunch tool is the standard ROS method for starting Gazebo’s simulated world and robots. To verify that Gazebo is correctly installed, we will launch the supplied willowgarage_world.launch shown in Figure 3-49 with the following command:

$ roslaunch gazebo-ros willowgarage_world.launch

A computer generated layout of Willow garage.

Now that we have verified Gazebo is installed correctly, we will be replacing the willowgarage_world.launch file with our world: a simplified simulated world of the unexplored Egyptian Catacombs and our intrepid AI rover. The AI rover’s scripts with adaptive intelligence and decision making will circumvent ancient dangers that might still await us.