Designing a System that Exposes Multiple CAN Devices to ROS while Interfacing with Master Device via Serial in Hardware

[kyleoptimotive]

Is your feature request related to a problem? Please describe.
I'm looking for input towards the best practices for accomplishing what I've described above. I've confirmed that I can 1. expose one device to ROS and 2. Talk to every device that is connected to the first device via CAN bus. Now I am seeking to expose all devices to ROS while being limited to one serial connection.

Describe the solution you'd like
On a high level, I would like each of the devices exposed to ROS so that they can be run by different controllers without needing to create new code/systems for each one (for example Ackermann, velocity/position, differential).

Hardware Configuration:
(host system) <---serial---> (device_0) <---CAN---> (device_1, ..., device_n)

Desired Behaviour in ROS:
(host system) <-> (device_0, device_1, ... device_n)

Describe alternatives you've considered
These are the ideas/options I have so far and I would appreciate insight.

1. Create virtual hardware interfaces through a Node that has the ability to communicate to all CAN devices.

• This node would publish/subscribe to topics that correspond to the hardware devices and would manage the mapping between those topics and communicating over serial/CAN.
• For example: Lets say we want to set the velocity of a device with CAN ID 1 dev_1 and we are serially connected to device with CAN ID 0 dev_0. ROS would see topics like /dev_0/velocity/command and /dev_1/velocity/command created by the intermediate node and publish to the topic pertaining to dev_1. Then the intermediate node would see that message and pass it through dev_0 to eventually reach dev_1 over CAN.

2. Create a custom ROS control system hardware for each robot using these CAN-chained controllers.

3. Any other suggestions you may have.

Additional context
I am using ROS Humble and Ubuntu 22.04.

My specific use case of this is I am trying to control multiple VESC motor controllers using ROS2 Control. The VESC controllers are connected to each other over a CAN bus and the master VESC is connected to the system running ROS over USB serial.

I am using sbgisen/vesc to create the interface between my VESC controller and ROS.

[saikishor]

Hello!

Why don't you use a System Hardware Component interface for this approach?. This can help you handle all your multi-actuator communication in a single plugin.