Re: [CAD_CAM_EDM_DRO] Re: The guts of Circular Interpolation

Hmmm, never thought about accel/decel because of backlash compensation.

How does the backlash work into the accel/decel and velocity control in
circular interpolation.

How about the jerk limits in the acceleration when transistioning from a
straigth line into an arc?

Pete

----- Original Message -----
From: "rotarysmp" <mark.wrathall@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, March 01, 2004 4:21 AM
Subject: [CAD_CAM_EDM_DRO] Re: The guts of Circular Interpolation


> Don't forget that you need to decelerate below the start spedd at
> each quadrant if back lash it to be applied.
>
> Regards,
> Mark
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Pete Miles" <petem@o...>
> wrote:
> > I am looking for either a website or some literature that explains
> in
> > detail what happens inside a CNC controller when executing a
> circular
> > interpolation command, either G01 or G02.
> >
> > It is my understanding that a CNC actually breaks up the arcs into
> a
> > set of smaller linear moves so that the cordal deviation with the
> > line segment and the arc are within the tolerance spec set in the
> Amp.
> >
> > These small line segments have a set of coordinates and a velocity.
> > Which causes both axis of the machine to move. But prior to
> moving,
> > it needs to calculate the accelerations and decelerations,
> distances
> > to move based on the acceleration values, adjusting the straight
> line
> > velocities so that the tool gets to the end of the small sub line
> > segment at the right time so as to maintain (or try to) velocity
> > through the entire arc.
> >
> > Now all of these tiny little calculations take time, and are
> repeated
> > many times during a single G02/G03 command. Then all these
> > calculations have to match up with the servo update clock, and when
> > things like jerk, acceleration, and velocity on an axis become
> > limiting factors, things have to slow down.
> >
> > What I am looking for is how all this is calculated. Does the CNC
> > controller do all the work, is the servo controller involved with
> > some of the calculations.
> >
> > Any info would be appreciated.
> >
> > Pete Miles
>
>
>
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