Re: [CAD_CAM_EDM_DRO] Newb question....

At 10:42 AM 10/1/2004, Jon Elson wrote:

>Aiden wrote:
>
> >I'm a lurker here, as time and money problems don't allow me to
> >actively pursue this hobby at present, but a question has occured
> >(sp?) to me. Is there any reason why you would not use stepper
> >motors with encoders or resolvers in a closed loop to minimize lost
> >steps or similar error?
> >
> >
>Yes. When a stepper motor loses a step under load, it cannot recover
>in any smooth manner. At best there will be a big jerk backwards and
>then forwards, again. At worst, and the usual state, any attempt to
>catch up
>to the desired position will just maje the motor stall.
>
>Secondly, none of the hobby-level software has any provisions to handle
>this. The only software I know of that could make a crude attempt would
>be EMC, but it would be totally closed-loop, and still could not recover
>from a lost step. The actual position would always be known, which would
>be a big help, but it when the motor loses a step, there's no way to command
>it to "try harder".
>
>If you want a servo system, which CAN do this, then just get a servo system,
>and solve the problem the right way.
>
>Jon

Jon, can you clarify this for me. I am using your USC with steppers with
encoders and EMC. If a stepper loses a step it does not recover? Or is
what you said above not apply to the USC because it is more like a servo
system?



- John