Re: [Emc-users] Tune-upn AC servomotor

[Dave E. <den...@ch...>]

On Dec 12, 2006, at 2:07 AM, Kasparov, Aram wrote:

> Hi Dave
>
> I am using MESA 5i20 card. Is any difference in tune up process  
> makes type of card that in use? (MESA vr VITAL)
Not that I know of.
Tuning in velocity mode is a bit different than tuning in torque mode  
but the goal is the same.
>
>
> Also, what is exact definition of "oscillate"?
   to move back and forth in a periodic manner as in a pendulum; sine  
wave.
>
> Any motion of motor should send some signals and oscilloscope  
> should show waves. If oscilloscope can't show wave it means that  
> oscilloscope is not sensitive enough.
>
plotting position vs time should give you a nice sine wave at a given  
frequency.
> So, can I say that oscillate means any motion of motor?
No, motion  in one direction is not oscillation; only when it goes  
back and forth.

If P is set low you  will get no motion; as you increase P the axis  
should get more and more jittery. Finally it should  sustain back and  
forth motion. Don't do this too long; just long enough to make  
certain it is not going to dampen out. Then multiply the P that   
produced that by   0.6 and that is a starting value for P. When you  
are doing this I and D are both set to zero.
After that works then go adjust FF1. That is my way of doing things.  
Others have different procedures and they work also.
>
>
>
> I am now moving to final stage of start putting controller/ 
> retrofitting Bridgeport machine for place where I am working.
>
> What is min. torque needed to move X-axis of Bridgeport mill? I  
> will use 1 to 6 timing belt reducer.
I don't really know. Jon Elson can probably give you a quantitative  
figure. 6:1 seems like a  pretty high ratio.
I tried 4:1, 3:1 and finally settled on 2:1 with SEM HT-30-H4-44  
brushed servo motors. It has enough power to
go 150 ipm which is about all one can get out of that type of way.
>
> Are any suitable motor from servo dynamics for that type of job?

http://www.servodynamics.com/MT30.html

If you want to go brushless then I have to experience.

Hope this helps.

Dave
>
>
>
> Thanks
>
> aramk
>
>
> ________________________________
>
> From: emc...@li... on behalf of Dave  
> Engvall
> Sent: Fri 12/8/2006 10:13 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] Tune-upn AC servomotor
>
>
>
> Hi Aram,
>
> A couple of things come to mind.
> Check your servo amp with 9-10 vdc on the input.... a nine volt
> battery is handy. :-)
> The axis should move out smartly,  close to the maximum velocity you
> want.
> If it doesn't then adjust the gain on the amp until it does.
>
> After that is verified then go back to tuning emc. IIRC typical P
> values for the Vital card are in the low thousands.
> Work toward getting P set at 0.6 times P when the axis just sustains
> oscillation. Leave it there while you work with other parameters.
>
> As for the halscope stuff: try getting on irc ... freenode.net   #emc
> and you should be able to get help.
>
> Dave
> On Dec 8, 2006, at 9:30 AM, Kasparov, Aram wrote:
>
>> Hi Dave.
>>
>> I am trying to see any wave type graph on oscilloscope but I can't.
>>
>> I star machine with very slow motion f0.01 in order to have enough
>> time to start oscilloscope, load them up as it described in manual.
>>
>> I loaded signals:
>>
>>  sig Xpos-cmd     (position command)
>> sig Xpos-fb      (position feedback)
>> pin pid.0.error  (position error)
>> sig Xoutput      (PID loop output)
>>
>> I only can see one yellow line and two read ones.
>>
>> If I reduce P to 20.0 then I can't see yellow line at all.
>>
>> I increased P to 583 (randomly pick that figure) and machine moves
>> very slow no matter how big F feed I put in.
>>
>> When P is small than machine moves faster indirectly from volume of
>> F feed.
>>
>>
>>
>> Am I doing something wrong?
>>
>>
>>
>> Thanks
>>
>> aramk
>>
>>
>
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