U00-L02-TurtleBotIsGo.md

template: ../media/TB4Template.pptx

Lesson Objectives

• Familiarize yourself with the TurtleBot 4
• Connect the TurtleBot 4 to your local WiFi.
• Update the TurtleBot 4
• Connect to the TurtleBot
• Run the teleop launch files.

The TurtleBot 4

• There are two variants of the TurtleBot 4.
• TODO: DIAGRAMS
• Turtle Bot 4 includes:
  • iRobot Create 3
  • RaspberryPi 4b - 4GB
  • OAK-D Pro
  • RPLidar
  • Circuit Board
• TurtleBot4 Lite
  • iRobot Create 3
  • RaspberryPi 4b - 4GB
  • RPLidar
  • OAK-D Lite

Setting Up Your TurtleBot -- Connect to WiFi

• Plug in dock, and place robot on dock to power it on.
• It will take a few minutes for the robot to boot.
• Using a Linux PC to connect to RPI in your WiFi settings:
  • SSID: Turtlebot4 Password: Turtlebot4
• SSH into robot from the same laptop: ssh ubuntu@10.42.0.1
  • Password: turtlebot4
• The TurtleBot comes with a preinstalled WiFi setup script.
• Call sudo wifi.sh -s "wifi_ssid" -p "wifi_password" -r REG_DOMAIN && sudo reboot
• REG_DOMAIN depends on your country, see this list.
• USA: US, Canada: CA, UK: GB, Germany: DE, Japan: JP3, Spain: ES.

Now Setup the Create3 Wifi

• TurtleBot has not one, but two computers on board and each of them needs to be connected to wifi.
• This procedure is used to connect the Create3 to your wireless network.
• Press both button 1 and 2 on the Create3 simultaneously until the light ring turns blue.
• The Create3 is now in AP mode, connect to its WiFi Create-XXXX
• In your web browser go to 192.168.10.1
• Click connect and enter your wifi SSID and password
• Wait for it to connect to wifi, the ring light will turn white.

Check Your Installation

• Give your TB4 a minute to save its configuration.
• Reboot the Turtlebot4 by pressing
• The TB4 should have a white ring light and play a tone when it has started.
• Now find your TurtleBot's IP address
• Open a terminal and SSH into the robot using: ssh ubuntu@<TB4 IP>
• The password is turtlebot4
• Let's check that everything is connected to the network, run the command
  • ros2 node list
• You should see the _internal/* nodes.
  • If these nodes are not visible then the Create3 is not connected to the network.

Setting up Teleoperation

• Now let's connect to the robot and put it in teleoperation.
• For this you'll need a bluetooth PS4 controller. Make sure it is charged!
• ssh into the robot and run the following commands to enable bluetooth pairing.
  • sudo bluetoothctl
  • default-agent
  • scan on
  • After entering scan on the controller will respond, "Discovery started"
• Now we'll put the controller into pairing mode by pressing and briefly holding the two buttons shown on the diagram.
• The front light will start blinking rapidly twice in a row.
• You should see something like [NEW] Device D8:E8:DD:8A:B9:30 <some string>
• At some point you should see something like [NEW] Device D8:E8:DD:8A:B9:30 Wireless Controller

Pairing the Bluetooth Controller

• Once you see the controller copy its MAC address. It is the series of numbers of letters separated by colons.
• Now run the following where is your controller's unique MAC address.
  • trust <MAC>
  • pair <MAC>
  • connect <MAC>
• You have now paired your bluetooth controller. You can exit the controller by calling exit
• On subsequent connections you won't need to run through every step. Instead you can run:
  • Check the controller is running with:
  • ubuntu@ubuntu:~/turtlebot4_ws$ sudo bluetoothctl paired-devices
    • Press buttons on controller
    • devices -- bluetooth will list devices
    • connect <MAC>
    • exit
  • If the device is there you're good to go.
  • Otherwise follow the steps above.
• If you see an error like Waiting to connect to bluetoothd...
  • The Bluetooth daemon is not running. Try running sudo systemctl start bluetooth
  • To make Bluetooth always start run, sudo systemctl enable bluetooth

Multiple Terminals with Byobu

• Before we put the robot into teleoperation mode, we need to review how to open multiple terminals in an SSH session.
• There are many terminal managers, also called multiplexers available for Linux. Examples include Byobu, Tmux, and GNU Screen.
• For our examples, we'll use Byobu, but you can use whatever you're comfortable with! It is also worth noting that byobu generally uses tmux as its backend.
• To start byobu simply type byobu in your terminal.
  • If byobu is not installed, simply run sudo apt install byobu.
• To create a new terminal simply press F2.
• To page through terminals use F3 and F4.
• shift-F2 - Split the screen horizontally and ctrl-F2 Split the screen vertically.
• shift-F3 - Shift the focus to the previous and shift-F4 Shift to the next split .
• ctrl-F6 - Remove this split
• ctrl-F5 - Reconnect GPG and SSH sockets
• Full documentation can be found here. or by running man byobu, or shift-F1 in Byobu.

Running Teleoperation

• ROS 2 uses "launch" files to run collections of small programs called nodes.
• We're going to run a launch file called "joy_teleop.launch.py", where "joy_teleop" means "joystick teleoperation"
• Create a terminal in your robot ssh session and run the following:
  • cd ~/turtlebot4_ws
    • Move to our ROS 2 "workspace."
  • source ./install/setup.bash
    • Tell the terminal we're using this ROS 2 workspace.
  • ros2 launch turtlebot4_bringup joy_teleop.launch.py
    • Run the program joy_teleop.launch.py found in the directory ~/turtlebot4_ws/src/turtlebot4/turtlebot4_bringup/launch/.
  • A bunch of stuff should appear on the screen.
  • Note that the tab key should automatically complete most of these commands after you enter the first few letters.

Moving the TB4 in Teleoperation Mode

• The TurtleBot4 controller operates as a "dead man's switch."
• A "dead man's" switch is a safety feature that is often used with robot controllers. The user must hold down the "dead man switch" at all times; this prevents the robot from moving if the controller is dropped or misplaced.
• For this controller "L", the button near your left index finger, is the deadman switch.
• There is a second dead man switch, the "R" button near your right index finger. This switch makes the robot move faster.
• The left joystick controls the robot's direction.
• The robot is smart, and will temporarily disable the controller if hits a cliff or a big bump. It may also do this if you reverse suddenly. This mode is indicated by the ring light turning yellow.

Docking / Undocking

• TODO: These two do not work.
• ros2 action send_goal /undock irobot_create_msgs/Undock '{}'
• ros2 action send_goal /dock irobot_create_msgs/DockServo '{}'

Alternative: Keyboard Teleoperation

• If you don't have a joystick, or don't feel like connecting it to the robot, you can also teleoperate it with a your keyboard.
• The steps are similar to the teleoperation mode.
• Create a terminal in your robot ssh session and run the following:
  • cd ~/turtlebot4_ws
    • Move to our ROS 2 "workspace."
  • source ./install/setup.bash
    • Tell the terminal we're using this ROS 2 workspace.
  • ros2 launch turtlebot4_bringup joy_teleop.launch.py
    • Run the program joy_teleop.launch.py found in the directory ~/turtlebot4_ws/src/turtlebot4/turtlebot4_bringup/launch/.
  • Now, in a new byobu terminal kick off the keyboard teleoperation.
  • ros2 run teleop_twist_keyboard teleop_twist_keyboard
  • Follow the directions on the screen.
  • To exit hit CTRL+C.

Advanced Teleoperation

• Teleoperation is fun, but what if we want to move the TurtleBot to a nearby room and pilot it using the camera?
• To do this we'll need a second laptop running ROS!
• On our laptop we'll run a program called RVIZ.
• RVIZ is ROS's one stop shop for visualizing a running robot.
  • RVIZ let's you see cameras, lidar, maps, the robot's state, and a whole bunch of other important information about your robot.
• To install RVIZ we'll first need to install ROS 2 on our laptop.

Installing ROS on Your Laptop

• We'll install ROS 2 Galactic Geochelone on your laptop.
• How you install ROS 2 will depend on your host will depend on your host OS.
• While ROS is open-source and can run on just about any OS, it doesn't mean it is easy to run it on every OS.
• If you are running Ubuntu 20.04 Focal Fossa then you can install ROS easily.
  • Follow this guide.
• If you ARE NOT running Ubuntu 20.04 then we recommend that you:
  • Install a virtual machine client.
  • Create a virtual machine and install Ubuntu 22.04.
  • Follow the directions above inside of the virtual machine.
  • We have created this tutorial for this process.

After ROS, Next Steps

• If the installation completed successfully you should be able to do the following:
• Create a new terminal.
• Activate ROS by calling source /opt/ros/galactic/setup.bash
• We will use a program called ros2 doctor. ROS Doctor is a command that will print out a variety of information about a ROS 2 system.
• Call ros2 doctor
  • If everything worked successfully that last line of the command should report: *All 4 checks passed
  • If something failed the ROS 2 Doctor should report something.
    • Run ros2 doctor --report and work with someone to correct the issue.

Install RViz

• We just installed ROS, but we still need to install RVIZ.
• We'll use a tool called apt to install RVIZ.
• Apt, also called Aptitude is the Debian/Ubuntu package manager. You can find, install, upgrade, and uninstall just about anything using Apt.
• It is worth familiarizing yourself with apt by running apt --help
• Run the command: sudo apt install ros-galactic-rviz2
• Warning: Apt will spit out a ton of information as it installs the package for you!

Running RViz

• If RVIZ2 installed successfully starting it should be fairly straight forward.
• First we intialize ROS by calling:
  • source /opt/ros/galactic/setup.bash
• If everything is setup correctly you should be able to run the following command and see all of the topics, or data streams on the robot.
  • ros2 topic list
  • ROS should spit out three dozen topics with names like \battery_state and \wheel_vels.
• Now we'll start RVIZ. In the terminal where you sourced setup.bash call:
  • rviz2
• You should see something like the image above.

Controlling RViz

• RViz is ROS's tool for visualizing everything about your robot.
• On the left of RVIZ you'll see a "Displays" pane that let's you configure what data you want to see.
• On the right you'll see visualization of your robot and the surrounding environment.
• RVIZ is highly configurable. You'll be able to see your robot, its sensors, and the data from the sensors.
• The view panes in RVIZ are configurable, and you can customize it quickly to suit your needs.
• The control of visualization is a different than Ignition.
  • Left mouse button rotates the view.
  • Right mouse button zooms the view.
  • Shift + left mouse pans the view.

Configuring RViz

• Now we'll setup RVIZ for teleoperation (remote driving).
• The first step is to set our reference frame, this will tell RVIZ how to display our data.
• On the left hand side of RViz you should see a "Displays" pane.
• Towards the top there should be a value that says "Fixed Frame" with a drop down to the right of it (see diagram).
• Set the fixed frame to base_link.
• In ROS, base_link means the "base" of the robot. For wheeled robots it is usually in the center
• This value needs to be set to see anything else in RVIZ.

Setup TF in RViz

• Next we're going to enable TF, which is ROS shorthand for "transform."
  • A transform is a simply a position on a robot relative to another position.
  • For example, one transform might be the position of the robot's camera with respect to its left wheel.
• To see the "base_link" in RVIZ find the TF section of the display pane and do the following:
  • Set the check box for TF
  • Set the check box for Show Names.
  • Set the check box for Show Axes.
  • Shrink the "Marker Scale," the size of the TF names, to be about 0.07
• You should see something like the image above.

Setup Camera and Laser

• Next we'll setup the TB4 camera and lidar.
• To view the LIDAR click Add in the display pane.
  • In the dialog that pops up select LaserScan.
  • Under LaserScan in the Displays pane click the checkbox to enable the dispaly.
  • Set the Topic to /scan
  • The laser scan should now be visible.
• To the view the camera click the Add button under displays.
  • In the dialog that pops up select Camera
  • Now enable the camera by clicking the checkbox in the Displays pane.
  • Set Topic to either /right/image_rect or /left/image_rect/

Try Different Configurations

• RViz is highly configurable. You can save and load various configurations to suit your application.
• We've barely scratched the surface of what RVIZ can do, but it is good to get familiar with it.
• A full list of features can be found in the RVIZ documentation.
• Take your robot for a spin and try different configurations!