Task 0 — Instructions

Before you begin

Everything here has been tested on Ubuntu 22.04 only, installed on the machine itself. Not a virtual machine, not WSL, and not another Ubuntu version — see Prerequisites & Installation. e-Yantra cannot help with queries from any other setup.

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Procedure

1. Install Ubuntu 22.04

If Ubuntu 22.04 is already on the machine, skip to step 2.

Resource	Link
Download ISO	ubuntu-22.04.5-desktop-amd64.iso
Installation walkthrough	Install Ubuntu Desktop — Canonical

Follow Canonical’s tutorial screen by screen. One choice in it matters for this theme: take Normal installation, not Minimal.

Then confirm the version:

lsb_release -a

Release must say 22.04 and Codename must say jammy. Anything else and you are on an untested setup — the versions of Python and the system libraries differ, and e-Yantra cannot support it.

Finally, update the fresh system:

sudo apt update
sudo apt upgrade

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2. Install MuJoCo 3.11

MuJoCo — Multi-Joint dynamics with Contact — is the physics engine that runs the maze. This theme uses MuJoCo 3.11, installed through its official Python bindings.

Install the Python toolchain

Ubuntu 22.04 ships Python 3.10, which is what this theme uses. You only need pip:

sudo apt update
sudo apt install python3-pip

python3 --version   # 3.10.x
pip3 --version

Install MuJoCo

Install the exact version — not the latest:

pip3 install mujoco==3.11.0

The version matters

Use ==3.11.0. A plain pip3 install mujoco takes whatever is newest that day, and a model that loads on one MuJoCo version can behave differently on another — which makes your results impossible to compare against the evaluation.

Verify MuJoCo

Check the version Python reports:

python3 -c "import mujoco; print(mujoco.__version__)"

It must print 3.11.0. Then open the interactive viewer:

python3 -m mujoco.viewer

A window should open with an empty scene, a grid floor, and the control panels down the left side. Dragging with the mouse should orbit the camera.

To confirm the physics engine itself is stepping — not just the window drawing — open the Simulation panel on the left and use its pause/play button (the space bar does the same). The simulation time next to it should climb while it is running and freeze the moment you pause. If the window opens but that clock never moves, the viewer is up but the engine is not stepping.

MJCF is just XML

Models in MuJoCo are written in MJCF, an XML format. The maze, the PacBot and the Ghosts are all MJCF files in the theme repository — you can open them in any text editor, and you will be reading them in Task 1.

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3. Install MQTT

MQTT is the messaging layer between your code and the simulation. You need two pieces: the broker that routes messages, and the Python client your code will use.

Install the broker

Mosquitto is the broker this theme uses:

sudo apt update
sudo apt install mosquitto mosquitto-clients

The service starts on install. Confirm it, and make it start on every boot:

systemctl status mosquitto
sudo systemctl enable mosquitto

Active: active (running) is what you want. Press q to exit the status view.

Verify a message goes through

This needs two terminals. In the first, subscribe to a test topic and leave it running:

mosquitto_sub -h localhost -t eyrc/pacbot/test

In the second, publish to the same topic:

mosquitto_pub -h localhost -t eyrc/pacbot/test -m "hello pacbot"

hello pacbot should appear in the first terminal straight away. A publish that returns silently while the subscriber prints nothing means the broker is not running — check the status command above.

Install the Python client

pip3 install paho-mqtt

python3 -c "import paho.mqtt.client; print('paho ok')"

The broker only listens locally

By default Mosquitto accepts connections on localhost port 1883 and nowhere else, which is all Task 0 needs — the simulation and your code both run on your machine.

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Done?

Head to the Task 0 — Submission page to generate your result file and upload it.