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General Exercise Running Procedure

Modified 2021-10-31 by tanij

This page describes the exercises’ infrastructure. This infrastructure affords a seamless method to build on existing baselines, test them in simulation, test them on robot hardware either remotely or locally, and then evaluate and submit them as challenges with the AIDO challenges infrastructure.

A Duckiebot that is initialized

Laptop configured, according to Unit C-2 - Setup - Laptop.

That you are able to submit a challenge according to Unit C-3 - Make your first submission.

Video Tutorial

Modified 2021-10-30 by Liam Paull

The video is at

Learn how to use the exercises infrastructure.

Getting Started

Modified 2021-10-31 by Jacopo Tani

Fork the mooc-exercices repository and clone it onto your computer.

Set up an upstream remote. From inside the directory you just cloned:

laptop $ git remote add upstream

Now to pull anything new from the original repository you can do:

laptop $ git pull upstream daffy

Enter the mooc-exercises folder that you just cloned do:

laptop $ cd mooc-exercises

In here you will see a number of folders. Each folder corresponds to an exercise.

The Anatomy of an Exercise

Modified 2021-04-03 by Liam Paull

Exercises should contain all of the following:


Modified 2021-04-09 by tanij

This contains information about the exercise. Example:

# Exercise configuration file

agent_base: "duckietown_baseline" # the agent base image to use
ws_dir: "exercise_ws" # directory that contains the code
agent_run_cmd: "" # the script in "launchers" to run the agent with
    - notebook:
        package_name: "encoder_pose"
        name: "odometry_activity"
    - notebook:
        package_name: "lane_controller"
        name: "control_activity"

The agent_base indicates which image to use as a baseline to build from. The mappings are listed here. Many of the existing exercises are build on the duckietown_baseline image which contains all of the code in the dt-core repository.

In the case that you are using the duckietown_baseline, any package/node that you create in the exercise_ws directory will be run instead of the one in the dt-core repository if the package name and node name match. This is achieved through workspace overlaying.

The ws_dir indicates the name of the subdirectory that contains the code that should be mounted into the image.

The agent_run_cmd indicates the command that should be run when the container is run to start things.

The notebooks contains the list of the notebooks that have to be converted to python scripts. For each notebook must be specified the name of the notebook name, and the name of the package where the generated script has to be copied package_name. Multiple notebooks can be listed.


Modified 2021-04-09 by tanij

As indicated above, the exercise_ws directory is where the code should go. For the case of ROS packages, they should go inside a src directory inside exercise_ws.


Modified 2021-04-09 by tanij

The assets folder contains two subfolders, setup and calibrations.

  • The setup subfolder contains all the configuration information (mostly in terms of environment variables) that are needed to run the various docker images that we are running (which depends on the configuration).

  • The calibrations folder contains robot calibrations with a similar directory structure as is on the Duckiebot.


Modified 2021-04-09 by tanij

The launchers folder contains scripts that can be run by the agent. Specifically, the one that is indicated in the config.yaml file will be run by default when the agent container is run or when your exercise is submitted through the challenges infrastructure.

You can specify different launchers to run depending on whether you are testing/developing with the exercises infrastructure or submitting through the challenges infrastructure.


Modified 2021-04-09 by tanij

The notebooks folder contains pedagogical notebooks that can be run. Some parts of the notebooks indeed are dedicated to tests, to check if the code is working properly before starting the simulation or testing on the Duckiebot.

Before running the test cells make sure you run also the cells with the code. There are different ways to run a cell:

  1. click on the play button on the top left of the cell.
  2. pressing crtl+enter.

The code in the notebooks can also be compiled and become accessible inside the code in the exercise_ws directory.

In order to do so, from inside the exercise folder run:

laptop $ dts exercises build

This command convert the notebook into a python script and place it inside the package in exercise_ws directory specified in the config.yaml file.

The same is when running the run command, with the difference that in this case the ROS workspace is not built:

laptop $ dts exercises run options


Modified 2021-04-09 by tanij

The requirements.txt file contains any specific python requirements that you need for your submission. Note that these are requirements need over and above the base image.


Modified 2021-04-09 by tanij

The Dockerfile contains the recipe for making your submission. In the normal case, this is relatively straightforward. We install the requirements, copy in the code and run a launcher.

The Exercises API

Modified 2021-04-09 by tanij

In the following we will describe the current commands that are supported within dts exercises and how they are used.

Building your code

Modified 2021-04-09 by tanij

You can start by building your code with:

laptop $ dts exercises build

If you go inside the exercises_ws folder you will notice that there are more folders that weren’t there before. These are build artifacts that persist from the building procedure because of mounting.

every time you run a dts exercises command you have to be inside an exercise folder or you will see an error.

Testing your code

Modified 2021-04-03 by Liam Paull

With dts exercises test you can test your agent:

  1. in the simulated environment,
  2. on your robot but with the agent code running on your laptop,
  3. with all of the code running on your robot.

Running in Simulation

You can run your current solution in the gym simulator with:

laptop $ dts exercises test --sim

Then you can look at what’s happening by looking through the “novnc” browser at http://localhost:8087 .

If you are running an exercise with a ROS-based baseline, you can use all of the existing ROS tools from this browser desktop. For example,
open up the rqt_image_view, resize it, and choose /agent/camera_node/image/compressed in the dropdown. You should see the image from the robot in the simulator.

You might want to launch a virtual joystick by opening a terminal and doing:

laptop $ dt-launcher-joystick

If you are running the duckietown_baseline, by default the duckiebot is in joystick control mode, so you can freely drive it around. You can also set it to LANE FOLLOWING mode by pushing the a button when you have the virtual joystick active. If you do so you will see the robot move forward slowly and never turn.

You might also explore the other outputs that you can look at in rqt_image_view.

Also useful are some debugging outputs that are published and visualized in RViz. You can open RViz through the terminal in the novnc desktop by typing:

laptop $ rviz

In the window that opens click “Add” the switch to the topic tab, then find the segment_markers, and you should see the projected segments appear. Do the same for the pose_markers.

Another tool that may be useful is rqt_plot which also can be opened through the terminal in novnc. This opens a window where you can add “Topics” in the text box at the top left and then you will see the data get plotted live.

All of this data can be viewed as data through the command line also. Take a look at all of the rostopic command line utilities.

TODO: add pictures.

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Testing Your agent on the Robot

If you are using a Linux laptop, you have two options, local (i.e., on your laptop) and remote (i.e., on the Duckiebot). If you are Mac user stick to the remote option. To run “locally”

laptop $ dts exercises test --duckiebot_name ROBOT_NAME --local

To run on the Duckiebot:

laptop $ dts exercises test --duckiebot_name ROBOT_NAME

In both cases you should still be able to look at things through novnc by pointing your browser to http://localhost:8087 . If you are running on Linux, you can load up the virtual joystick and start lane following as above.

Interactive Mode

You may find it annoying to completely shut down all of the running images and restart them to make a simple change to your code. To make things faster, you can use the --interactive flag with dts exercises test.

In this case, when all of the containers other than the agent have started, you will be given a command line inside the agent container (overriding the comand specified in config.yaml. From here you can run your launcher from the command line manually.

If you are running an exercise based on the duckeitown_baseline image, the first time you will have to start the “interface” part of the agent. To do this run

laptop container $ launchers/

You will see some output of some ros nodes starting. At the end, if you push ENTER you will get your command line back. Then you can run the lane_following demo using your lane_controller by running

laptop container launchers/

You can do the normal thing of going to novnc and putting it into lane following mode or driving around with the joystick or whatever.

If you would like to change your code and re-run, just edit your code on your laptop, and then go to that terminal and do CTRL-C. You will see everything start to shut down. Then you can simply rerun the agent and it will have the new code that you just modified since it’s mounted into the agent container. So just do launchers/ again and it will start up again.

You will see an output from the anti-instagram node saying it’s waiting for the first image. Don’t worry, if you go to novnc and put the agent in lane following mode or drive with the joystick, it will start to receive images and that output will go away

There is a timeout on the simulator, so if you do CTRL-C and then spend a while editing your code, it’s likely that the simulator will have shut down. So either leave it running while you edit your code or just restart everything. You can get out of your terminal by typing

laptop container $ exit