Learning Experience (LX): ROS Basics

Find the most up-to-date instructions on how to run LXs on the Duckietown manual.

About these activities

In this learning experience, you will learn the basics of ROS (Robot Operating System).

Instructions

NOTE: All commands below are intended to be executed from the root directory of this exercise (i.e., the directory containing this README).

The recommended way to use this repository is to make a fork and then clone that fork. This can be done through the GitHub web interface. However, you are also free to simply clone this repository and get started.

This exercise can be run on a real Duckiebot or on a virtual Duckiebot in the Duckiematrix.

1. Make sure your exercise is up-to-date

In case your instructor has updated something in this repo, you should make sure everything is up to date (this assumes that you created a fork):

git remote add upstream [email protected]:duckietown/lx-ros-basics
git pull upstream <branch>

NOTE: Example instructions to fork a repository and configure to pull from upstream can be found in the duckietown-lx repository README.

2. Make sure your system is up-to-date

• 💻 Always make sure your Duckietown Shell is updated to the latest version. See installation instructions

• 💻 Update the shell commands: dts update

• 💻 Update your laptop/desktop: dts desktop update

• 🚙 Update your Duckiebot: dts duckiebot update ROBOTNAME (where ROBOTNAME is the name of your Duckiebot - real or virtual.)

3. Work on the exercise

Launch the code editor

Open the code editor by running the following command,

dts code editor

Wait for a URL to appear on the terminal, then click on it or copy-paste it in the address bar of your browser to access the code editor. The first thing you will see in the code editor is this same document; you can continue there.

Walkthrough of notebooks

NOTE: You should be reading this from inside the code editor in your browser.

Inside the code editor, use the navigator sidebar on the left-hand side to navigate to the notebooks directory and open the first notebook.

Follow the instructions on the notebook and work through the notebooks in sequence.

Testing with the Duckiematrix

To test your code in the Duckiematrix, you will need a virtual robot. You can create one with the command:

dts duckiebot virtual create [VBOT]

where [VBOT] can be anything you like (but remember it for later).

Then you can start your virtual robot with the command:

dts duckiebot virtual start [VBOT]

You should see it with a status Booting and finally Ready if you look at dts fleet discover:

     | Hardware |   Type    | Model |  Status  | Hostname 
---  | -------- | --------- | ----- | -------- | ---------
[VBOT] |  virtual | duckiebot | DB21J |  Ready   | [VBOT].local

Now that your virtual robot is ready, you can start the Duckiematrix. From this exercise directory, do:

dts code start_matrix

You should see the Unity-based Duckiematrix simulator start up. The startup screen will look like:

From here, you can click anywhere on the window and click [ENTER] to make it become active. From here, you can move the duckie towards the Duckiebot with the 'w', 'a', 's', and 'd' keys or you can move the camera angle to view the Duckiebot with the mouse. Alternatively, you can change to an overhead view by pressing 'v', which will give you a view that looks like this:

Build the Code

You can build the code with

dts code build -R ROBOTNAME

where ROBOTNAME can be either a real or virtual robot.

Testing the code

Then you may run your code with

$ dts code workbench -R ROBOTNAME [-m]

where ROBOTNAME can be either a real or virtual robot, but if it is a virtual robot, you should include the -m option to indicate that you want to test it in the Duckiematrix.

Time to Start the first Notebook!

Credits

This learning experience is provided by Duckietown in collaboration with Prof. Romulo Meira-Goes, Ph.D (Pennsylvania State University). Visit the Duckietown Website for more learning materials, documentation, and demos.