Re: [CAD_CAM_EDM_DRO] Re: Higher performance systems

Hi Mariss;

Just to remind you about them, there are such things as log/anti-log amps, and
if you don't mind dealling with them, they'll not only do trig, they'll do it
in real-time, as in right now, immediately. The ADC's, or DAC's you might need
for translation to/from digital signals might waste some time though.

Bill

On Thu Aug 28 16:25:04 2003 Mariss Freimanis wrote:

>Leslie,
>
>Ah, a topic near and dear to me just right now! The conundrum is
>vector path fidelity and a constant vector velocity are mutually
>exclusive.
>
>To accurately follow a path means you have to decelerate to a stop at
>the end of every line segment which is irritatingly slow and noisy.
>
>You can "round" line segment nodes to keep a constant contouring
>velocity. It is a computational nightmare though, having to insert
>arcs between nodes whose start and end angles and radii depend on a
>given axis set acceleration and velocity. The "on the fly"
>trignometry and path look-ahead schemes get real ugly real fast.
>
>I have come up with a method that neatly sidesteps those problems
>entirely; it is computationally trivial and acts automatically. In
>effect, the faster you go, the "rounder" the nodes are.
>
>The method outputs a moving average of velocity, effectively
>integrating velocity with time. A step change in velocity gives a
>ramped change, a ramped velocity results in an S-shaped velocity
>profile.
>
>As you probably know the G2002 is up and running using this
>algorithm, now on 3-D moves (XYZ). The results are very pretty indeed.
>
>Mariss
>
>
>
>
>--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Leslie M. Watts"
><leswatts@a...> wrote:
>> Mariss,
>> I think of the accel in terms of minimum corner radii.
>>
>> Radius= velocity squared/acceleration
>>
>> ... for more calculator fun.
>>
>> With 20 amps x 70 volts peak one can move a lot of
>> mass pretty quickly!
>>
>> I certainly agree with you and Jon that you won't
>> get to 1000 ips with a 5 TPI ballscrew!
>>
>> Leslie M.Watts
>> L M Watts Furniture
>> Tiger Georgia USA
>> http://home.alltel.net/leswatts/wf.html
>> Engineering page:
>> http://home.alltel.net/leswatts/shop.html
>> CNC surplus for sale:
>> http://home.alltel.net/leswatts/forsale.html
>> CNC carved signs:
>> http://home.alltel.net/leswatts/signwp.html

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