On Sun, 25 Sep 2011, Chris Morley wrote:
> Date: Sun, 25 Sep 2011 09:57:03 +0000
> From: Chris Morley <chrisinnana...@hotmail.com>
> Reply-To: EMC developers <emc-developers@lists.sourceforge.net>
> To: EMC DEV <emc-developers@lists.sourceforge.net>
> Subject: [Emc-developers] servo scale setting questions
>
>
>
>
> In the forum I had a user ask about servo setting in PNCconf and realized
>
> I didn't have good answers. Peter answered the fellows question but I am
>
> digging into the question so I can better understand things and maybe
>
> improve the docs a bit.
>
>
>
> In the manual under the TRAJ heading it talks of servo related settings.
>
>
> In particular output_scale and output_offset.
>
> Now it uses some very technical wording and is quite tough to understand IMHO.
>
>
>
> First off unless I am missing something, if some one is using HOSTMOT2 PWM
>
> there is no setting output_offset. software PWMgen has offset. Is that
> correct?
> In which case the manual should state that offset will be used only if
> available.
> now PID Bias could do the same thing couldn't it?
>
>
>
> Second scaling: If I understood Peter the scaling could be set to really any
> unit
>
> you want as long as the PID max output is set properly too.
>
> In Peter's opinion setting scaling to 1 (which would be PWM duty cycle) would
>
> make sense (particularly if using H-bridge amplifiers) .
>
> but setting the scale to represent voltage or motor speed would be reasonable
> too?
>
>
>
> for instance if one was using +-10 volt amps, and one wanted output to be in
> volts
>
> one would set output_scaling to 10 and PID max output to 10. yes?
Thinking about this a little more, I think theres a good argument for
setting output scaling to the maximum velocity in machine units per second, at
least for velocity mode servos and HBridges (which are voltage mode which is
close to velocity mode)
The advantage of this scaling (I think) is that the basic PID units
are normalized for both inch and metric machines so PID values can be the same
for both. That is the input to the PID comp is already in machine units, so to
maintain proportionality, the output of the PID comp should also be in machine
units.
>
>
> or if using an 7i29 H-bridge scale could be 1 and PID max output might be .975
> (this was as per Peter ) because H-bridges can not be fully on.
>
> In PNCconf the default setting for output scale is 1 and PID max output is 10
> which I'm pretty so is totally wrong.
>
> Thanks for helping me clear this up.
> Chris M
>
Peter Wallace
Mesa Electronics
(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.
------------------------------------------------------------------------------
All of the data generated in your IT infrastructure is seriously valuable.
Why? It contains a definitive record of application performance, security
threats, fraudulent activity, and more. Splunk takes this data and makes
sense of it. IT sense. And common sense.
http://p.sf.net/sfu/splunk-d2dcopy2
_______________________________________________
Emc-developers mailing list
Emc-developers@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-developers
