Motor selection for torque control up to 2Nm

Hi all,
I need torque controlled motors for a robotic application. The motors should produce torque up to 2Nm at a speed (possibly) greater 30 rpm.
I have looked to some gimball motors, such as this: https://eu.robotshop.com/products/ipower-motor-gm5208-24-brushless-gimbal-motor
I could not find much about the specifications. In any case, I guess that this motor, as any other cheap gimbal motor (?), is not capable to deliver out of the box the torque I need and would require a gearbox. Is there any gearbox for these kind of motors? Do you know if there any cheap solution (< 100 euros) to my problem?

I have seen that there are several stepper motors I could use. However, as far as I understood, torque control for stepper motors is possible only through voltage and thus is not very accurate. What accuracy can I expect from this approach? The application requires also the torque to be accurate.

More in general, what solution would you choose?

Thank you!

Pietro

Hi Pietro, welcome to SimpleFOC!!

Unfortunately, robot actuators with the performance you want are typically a lot more than 100$ :frowning:

You may want to look at this thread: Xiaomi Cyber dog geared motor ~$60

At 12Nm torque and $60 cost this motor is very unique. There are some users on our forum working on porting SimpleFOC to its driver, but of course you could also use the driver as it is with its standard firmware, or replace it with your own driver.

The iPower motors are quite nice gimbal motors. I’d recommend them.

And the 5208-24 specs say it has:
Load torque(g·cm): 1800-2500
(from: GM5208-24T Gimbal Motor )

So it looks like it actually meets your requirement?

Stepper motors are much harder to drive using FOC because of their high pole counts. Also, they tend to be quite heavy, which can be a concern for robotics applications.
You are correct that SimpleFOC does not support current sensing for stepper motors at the moment. But it is likely to be added in the future at some point.
At the moment you can use “estimated current” mode (if you set the phase resistance of your motor) with steppers, but not real current control.

I think we’d need to know a little more about the use-case to give good advice. Robotics is a wide subject. It sounds like you’re looking more for something for a robot arm than a wheel?