Cinématique avec axes "redondants" (+présentation)

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10 Feb 2015 21:20 #55860 by andypugh
andypugh replied the topic: Cinématique avec axes "redondants" (+présentation)

vincentECN wrote: It's that i begin to understand now... but as i said, i'm affraid to do a wrong change and damage the machine (like one joint will diverge and go very fast on limits).


If you have working f-error detection, and LinuxCNC can disable the drives, and you have limit witches, then it should all be fine....

Rather than make a simulated configuration it would be better to make a hardware test setup. Assuming that you already have the leadscrew, encoder and secondary carriage, then you could create a simple 1-axis config with a small servo motor.

Alternatively a test config with one axis and connected to the real machine, but with the motor uncoupled from the system. The PID tuning would be very different for the uncoupled motor, so this would have to be a separate config. However as it would be working with the real hardware it would be possible to watch the motor move in the opposite direction to your hand-cranked leadscrew.
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23 Feb 2015 23:22 #56243 by vincentECN
vincentECN replied the topic: Cinématique avec axes "redondants" (+présentation)
So,

I have modified hal files and ini file for the real machine (after had an overview of the configuration, see "Document Scannable").

There is few modif (to add a disturbance on X), like this :

In INI, only one line in [AXIS] for the scale of new encoder (i can also directly add on hal ?) :
INPUT_SUM_SCALE =       -200

In montenc_motion.hal :
loadrt sum2 count=1
addf sum2.0 servo-thread

linksp Xpos-fb <= motenc.0.enc-00-position
linksp Xpos-fb <= motenc.0.enc-00-position
net Xpos-fb sum2.0.in0

linksp Ufic <= motenc.0.enc-03-position
net Ufic => sum2.0.in1
setp motenc.0.enc-03-scale [AXIS_0]INPUT_SUM_SCALE 

net XUpos-fb sum2.0.out

In core servo.hal :
net XUpos-fb axis.0.motor-pos-fb => pid.0.feedback

Did i miss something ?

And first, before try to add a real encoder, i want to try with a manual entry on hal, for the real machine. In motenc_motion.hal, instead of "linksp Ufic <= motenc.0.enc-03-position" Can i do like this :
newsig Ufic float
net Ufic => sum2.0.in1
sets Ufic 0

? But i'm wondering, if I define Ufic, for example, by sets Ufix 0.1 (in "show hal configuration"), the machine will think that there is 0.1 mm of displacement at each period ? (so, can escalate quickly) ??

I want to be sure before trying in the next few days. ^^"

Thx for your help !
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24 Feb 2015 03:48 #56253 by andypugh
andypugh replied the topic: Cinématique avec axes "redondants" (+présentation)

vincentECN wrote:

linksp Xpos-fb <= motenc.0.enc-00-position
linksp Xpos-fb <= motenc.0.enc-00-position
net Xpos-fb sum2.0.in0


This is a rather old-fashioned way to define nets. You can just use:
net xpos-fb motenc.0.enc-00-position sum2.0.in0
net xdelta motenc.0.enc-03-position sum2.0.in1

etc

But i'm wondering, if I define Ufic, for example, by sets Ufix 0.1 (in "show hal configuration"), the machine will think that there is 0.1 mm of displacement at each period


No, the addition will only be cumulative if you feed-back the result of the addition to the input.

You can actually run the basic config in a stepper simulation if you want, but I would run it on the actual hardware with the motor shaft disconnected I think.
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24 Feb 2015 21:22 #56269 by vincentECN
vincentECN replied the topic: Cinématique avec axes "redondants" (+présentation)
Thx for your response. (so i've seen a mistake with two lines in double...)

andypugh wrote: but I would run it on the actual hardware with the motor shaft disconnected I think.


So, what can i observe in this case ? If the hal is good ?
And when you say "disconnect the motor shaft", it's from the driver card ?
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24 Feb 2015 21:37 #56270 by andypugh
andypugh replied the topic: Cinématique avec axes "redondants" (+présentation)

vincentECN wrote: And when you say "disconnect the motor shaft", it's from the driver card ?

#

No, I mean disconnect the motor from the machine mechanically so that you can't damage the actual metal parts through misconfiguration.
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24 Feb 2015 21:41 #56271 by vincentECN
vincentECN replied the topic: Cinématique avec axes "redondants" (+présentation)

andypugh wrote:

vincentECN wrote: And when you say "disconnect the motor shaft", it's from the driver card ?

#

No, I mean disconnect the motor from the machine mechanically so that you can't damage the actual metal parts through misconfiguration.


Hmmm. Ok. (But it seems it will be difficult on this industrial machine. I will see with a technician.)
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24 Feb 2015 21:52 #56272 by andypugh
andypugh replied the topic: Cinématique avec axes "redondants" (+présentation)

vincentECN wrote: Hmmm. Ok. (But it seems it will be difficult on this industrial machine. I will see with a technician.)


In that case, perhaps you just need someone ready at thee-stop switch and to be sure that the limit switches work.
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