Motors requirements

[EmmanuelMess]

Why are the mjbots motors specifically required, is there any problems replacing the motors with CyberGear or something similar?

The mjbots robots seem to be out of stock and cost 4 times more (8 times after Argentinean tariffs) than the CyberGear ones, is there a way to replace them?

[stephane-caron]

Yes, this is something that has evolved since the beginning of the project. At the onset of the project, qdd100 beta 2 actuators cost 400-500 USD if I remember correctly, while they are at 879 USD as of today.

The upkie software doesn't need qdd100 specifically. It requires that all motors are commanded by moteus controllers over CAN-FD. You could therefore swap the actuator body as long as a moteus is driving it.

I haven't experimented directly with alternatives, but from what I gather, I would expect a CyberGear to be more work to adapt to a moteus, as it ships as an integrated unit with motor, gearbox and controller expecting its own CAN protocol. To run it from a moteus, you'd likely have to disassemble it and remove the motor driver board. The CubeMars AK80-9 could be an easier alternative if you buy the driverless ("bare") version. A relevant thread on the mjbots Discord discussed this:

I'm looking at using a Cubemars AK80-9 actuator for a mini cheetah(is) quad. I've got a couple questions. First, does anyone know the connector (if there is one) for the driverless version? The version with the driver only exposes the two power wires for the driver. I assume the driverless version has a 3 wire connector? Also, are there any gotchas for using a [[moteus controller]] for for this application/actuator, and which model should I be looking at? I'd much prefer a well supported, open driver like the moteus if possible.

If I understood correctly, the takeaway was that the moteus r4, n1 or x1 controllers would all work with it. Once you have a motor + gearbox with bare phase leads, setting up a moteus is a matter of soldering the three phases, gluing a diametric magnet to the rotor (for commutation) and running moteus_tool to calibrate.