I have an application where I need a motor to produce a very constant/smooth velocity (< 5% velocity ripple) from speeds as low as 0.3 rpm up to 600 rpm. I currently have an ODrive S1 and an iPower GM5208-12 motor. The ODrive is fully capable of reaching my desired speeds. However, even with the anticogging feature enabled, I observe significant velocity ripple (~ ±70%) at 0.3 rpm. I assume this is just a limitation of how well the cogging torque can be compensated for. I hoped that a motor intended for camera gimbals would be good enough, but it doesn’t seem so.
The documentation of the ODrive anticogging feature mentions the following: “Therefore, if you find anticogging to give unsatisfactory results for your application, consider selecting a motor that is specifically designed for low cogging torque. Such motors are typically recognized by their skewed magnet or stator arrangement.” (Anticogging — ODrive Documentation 0.6.11 documentation)
I tried to look for such motors, but was unable to find any that are freely available. All that I found were specialty motors for space/military/… applications, only available upon request. Does anyone have a source for these motors, with skewed magnets/slots or even ironless or coreless?