Robot Architecture: Parts, Sub-Parts and Remotes
When robots communicate with each other, they can share resources and operate collaboratively. This document explains how to establish secure connections between robots.
Robots are organized into parts, where each part represents a computer (a single-board computer, desktop, laptop, or other computer) running
viam-server, the hardware components attached to it, and any services or other resources running on it.
Every robot has a main part which is automatically created when you create the robot.
Multi-part robots also have one or more sub-parts representing additional computers running
There are two ways to link robot parts:
Sub-part: If you have two computers within the same robot, use one as the main part and connect the other to it as a sub-part.
Remote: To connect two computers that are parts of different robots, add one robot part as a remote part of the other robot.
Connections between robots are established using the best network path available.
When you configure a remote or a sub-part, the main robot part can access all the components and services configured on the remote robot part as though they were entities of the main robot part. This is a one-way connection: the main robot part can access the resources of the remote robot part, but the remote robot cannot access the resources of the robot part remoting into it.
Configure a sub-part
You can make a multi-part robot by first configuring one part which is the “main” part, and then configuring one or more sub-parts. The main part will be able to access the resources of its sub-parts. Sub-parts will not have access to the resources of the main part.
Use the parts drop-down menu in the top banner of your robot’s page on the Viam app to add a new sub-part:
To delete a sub-part or make it the main part, use the buttons in the top right of the Config tab.
Configure a remote
To establish a connection between a part of one robot and a part of a second robot, configure a
remote on the first robot’s part.
Go to the Viam app robot page of the robot part to which you wish to establish the remote connection. This is the robot part whose resources will be accessible to the other robot part.
Click the Code Sample tab.
On the Language toggle, select Remotes.
Click Copy JSON.
Go to the Viam app robot page of the robot part from which you want to establish a remote connection. This is the robot part that will be able to access the resources of the other robot part.
Click the Config tab, click the Remotes subtab, and select JSON mode.
Click Create Remote.
Paste the remote config you copied in step 4 into the empty field.
Click Save Config in the bottom left of the screen.
Using remote parts and sub-parts with the Viam SDKs
Once your sub-part or remote part is configured, you can access all the components and services configured on the sub-part or remote robot part as though they were resources of your main robot part. The only difference is that the names of the components have the remote robot part name prepended to them. For example, instead of calling
servo = Servo.from_robot(robot=robot, name='my_servo')
you need to call
servo = Servo.from_robot(robot=robot, name='my-sub-part-name:my_servo')
servo = Servo.from_robot(robot=robot, name='my-other-robot-main:my_servo')
For an example that controls a motor that is a component of a sub-part, see the Mock Robot tutorial.
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