@ LarsK
I am thinking the text you quoted is probably out of date. I cannot think of a single situation nowadays in which an open-loop stepper-based solution can offer better performance than a comparable-sized closed-loop digital servo solution. The only thing is, the digital servo solution is likely to cost 5 to 10 x as much as the stepper based one. :(
As Misan wrote above, he is exploring a different solution space to the problem of linear or rotary actuators than the open-loop steppers-based solution space we are used to.
If we can get digital BLDC servos to approach the price range of same-size steppers with same or higher resolution, this could be revolutionary, not only for RepRap 3D printing, but also for DIY CNC and actually any kind of DIY robot.
As far as I know industrial CNC machinery and robot manufacturers have abandoned open-loop stepper based motion for closed-loop (servo) actuators en masse, because they are not as cost-bound as we RepRappers are, and a closed-loop approach can do pretty much anything an open-loop one can, only better.
I am thinking the text you quoted is probably out of date. I cannot think of a single situation nowadays in which an open-loop stepper-based solution can offer better performance than a comparable-sized closed-loop digital servo solution. The only thing is, the digital servo solution is likely to cost 5 to 10 x as much as the stepper based one. :(
As Misan wrote above, he is exploring a different solution space to the problem of linear or rotary actuators than the open-loop steppers-based solution space we are used to.
If we can get digital BLDC servos to approach the price range of same-size steppers with same or higher resolution, this could be revolutionary, not only for RepRap 3D printing, but also for DIY CNC and actually any kind of DIY robot.
As far as I know industrial CNC machinery and robot manufacturers have abandoned open-loop stepper based motion for closed-loop (servo) actuators en masse, because they are not as cost-bound as we RepRappers are, and a closed-loop approach can do pretty much anything an open-loop one can, only better.