Stepmotor vs brushless DC servo

I prefer to use commutated (regular DC, or brushless with appropriate sensors) motors for highly inertial loads. With steppers you either have low enough inertia that you can just start stepping, or you have to ramp up you acceleration. The problem is that this ramp has to be completely open-loop -- and I'm never happy with that.

So if it were me, I'd go with the brushless motors.

A stepper tightly coupled to an encoder with as many steps as the motor (or a multiple of that) can be driven just like a brushless motor with Hall-effect switches. the dividing line is a bit arbitrary. Bypass the hall effects, driving the coils directly from logic and a typical brushless motor can be driven like a three-phase stepper.

Jerry

Granted. But then you're back to something commutated. It solves the problem at the cost of more complexity, which is exactly what I was recommending.

Out of curiosity: have you done this? I can see how it would work, but you'd pretty much need a microprocessor with some clever start-up code.