[Coco] George's CNC Machine (WAS: Something else)

Ron Bihler rbihler at msn.com
Wed Sep 24 09:12:36 EDT 2008


>
> Is it not possible to precompute the math?  I.e., do something akin to
> compilation - take the time up front to do all the calculations, before
> the CNC machine gets any commands at all?  Or does it require feedback
> from the machine?
>
> C.
>
>
I see no reason this would not be possible, however this could be another 
tradeoff of file size and transfer speed - compared to computation.

Two primary system for moving the motors, Passive and Active.
Passive, you send the commands to the motors at the proper timing and assume 
they did what was requested of them, most hobby systems do just this.  In 
the case of stepper motors it works pretty well as long as the movements are 
kept within the speed requirements of the motors and nothing causes more 
force then they can handle.  If the speed or power is exceeded then the 
motors will miss a step (Actually 4 or more) depending on the motor.

Active, this system has a feedback loop and ensures the motors have done as 
expected.  Again depending on the support hardware, some handle this for the 
CPU. Or if the cpu is required to maintain the encoder counts as well.

Chuck this might be a fun project, I may need to look into this down the 
road. I atcually have a project that a dedicated system would be a benifit.

Ron







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