How to connect FOC driver to Pixhawk?

PX4 Autopilot
1

Hello everyone,

I’m currently working on building a Pixhawk-based autonomous rover. The initial setup with the Rover firmware on a Pixhawk 6C went smoothly, but I’ve run into a challenge: my motor drivers use the FOC (Field-Oriented Control) protocol, and it seems that Pixhawk doesn’t have direct/native support for it.

My idea was to integrate a Raspberry Pi as a companion computer, with the plan to subscribe to the topics exchanged between QGroundControl and Pixhawk, and then channel those commands to the FOC-based motor drivers.

Has anyone here tried something similar—either connecting FOC-controlled motors with Pixhawk, or working with the MAVLink/QGC topics for custom motor control?

Any guidance, experiences, or suggestions would be greatly appreciated!
Thanks in advance for your help.

2

I think you have some confusion about the control architecture. FOC is a control method not a protocol. The ESC firmware performs the FOC. The protocol between FC and ESC is PWM/DShot/etc. The Flight controller updates the PWM/DShot control signal from the estimation/control pipeline in FC firmware. Generally a companion computer like the Pi is sending position/velocity/attitude setpoints. My advice is to spend a couple of days learning about the architectural stack from ESCs to GCSs and understand how the various pieces interact. I would suggest using an LLM as a tutor.

3

Hey, thanks for the advice. The actual issue i am facing is having a FD CAN interface for my BLDC driver (Moteus n1) which natively operates on FOC. By any chance do you know how to connect FD CAN ESC to a Pixhawk 6c ?

4

The ESC will need to support the DroneCAN protocol (which it looks like that one does not). But it also looks like the firmware is open source so I would ask the question in that community.

Check out these doc pages on DroneCAN

5

Quick update on the issue!

Thanks for the advice again. we managed to command the wheels by using a companion computer between Pixhawk and wheel motors. Though it is an open loop system, it is doing the job for now.

For all the people who are trying to connect a motor with communication protocols that pixhawk doesn’t support, PWM is the way to go.
Good luck!stereo camera