Create a project

create-solarian writes a project: a Python package plus a conf/ directory. The directory name is up to you. This course uses so106, because that is the arm you are building.

Scaffold it

From a directory where you keep code:

create-solarian so106
cd so106

You should see a short tree printed, and a new so106/ folder. The layout is:

so106/├── conf/│   ├── controller.yaml          # solarian run-controller│   ├── robot.yaml               # solarian run-robot│   ├── server.yaml              # solarian run-server│   ├── commands/│   │   ├── record.yaml          # solarian record│   │   └── replay.yaml          # solarian replay│   ├── training/│   │   └── lerobot_act.yaml     # one example training file│   └── deployment/│       └── localhost.yaml       # addresses and device paths├── so106/│   ├── __init__.py│   ├── settings.py              # which classes to run│   ├── robot.py                 # So106Robot│   ├── controller.py            # So106Controller│   ├── server.py                # So106Server│   ├── observation.py           # what the robot reports│   ├── action.py                # what the controller sends│   ├── modules/│   │   └── example_module.py    # a sketch you will replace│   └── dataset_ops/│       └── drop_short_episodes.py└── pyproject.toml

These files are:

• so106/settings.py tells Solarian which classes are your robot, controller, and server.
• robot.py is the machine: one class attribute per module. The attribute's name is the module's name everywhere else.
• controller.py is the decision. Keys, and later skills, live here.
• server.py is the relay. Leave the generated class alone.
• observation.py and action.py are the schema of the messages between robot and controller. They have to name the same modules the robot declares. Solarian checks this when the classes are defined.
• conf/ is Hydra config. localhost.yaml is the only file that should contain a serial port or an IP address. The other files refer to it as ${deployment....}, so moving the robot to another computer is a new deployment file, not a hunt through the project.
• pyproject.toml makes the folder an installable package.

The generated robot.py imports an example arm from example_module.py, and that example imports a Feetech servo driver you have not installed yet. For this chapter the robot is empty on purpose. Replace the three files below so the first run has nothing to connect to.

so106/robot.py:

from solarian.core import Robot


class So106Robot(Robot):
    pass

so106/observation.py:

from solarian.core.observation import Observation


class So106Observation(Observation):
    pass

so106/action.py:

from solarian.core.action import Action


class So106Action(Action):
    pass

You can delete so106/modules/example_module.py or leave it. Nothing imports it now.

Install the project

The package has to be importable. From the project root:

pip install -e .

-e means editable: the next time you save robot.py, the installed package is already the file you saved. You do this once per environment, and again if you change pyproject.toml.

Run it

Open three terminals in the project directory.

solarian run-server

What you should see:

• The server starts and waits.
• The robot connects to it and sits there. There is no hardware and no simulator yet, so this is quiet.
• A controller window opens. It has no camera image, because the robot has no camera.

Quit each process with Control-C. You will start them again every chapter.

Where the name has to match

One string is about to show up in four places, and they must be identical:

The next chapter creates right_arm. If any of the four disagree, Solarian raises a TypeError when the class is defined, before the robot starts. That error is the useful kind: read the name it complains about and fix the one that differs.

Next: build the robot.