You definitely will need a higher resolution encoder if you need good velocity limiting in torque control mode. Your maximum gain is usually proportional to the encoder resolution, so you won’t be able to achieve a high gain like that with hall sensors. I also see some issues with your magnetic encoder mounting, I would recommend you carefully review this article: Designing for Magnetic Encoders — ODrive Documentation 0.6.11 documentation
What’s the issue with using an encoder in your final application? Why do you say that wouldn’t work?
Do you maybe have the option of changing to a different motor? But I agree, there’s not a very good way to add an encoder to that. One option is to tune the hall gains at a few different speeds, and dynamically interpolate between gains based on the speed, but that may be a lot of extra work and external code needed.
