Mazak Micro Slant 15 Retrofit

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22 Nov 2022 20:21 - 22 Nov 2022 20:27 #257370 by Masiwood123
..many people from my environment are trying to modify kuka welding robots, but without success, precisely because of mach3 limitations and those resolvers:))..it seems to me that he would have a lot of work here too..btw, it's all the fault of dirty politics on both sides, my grandfather came from Pristina in the 60s, his neighbor told him- ``that he was a good man and that it would all be ours one day``, and it came true. , after all, I can't wait for the situation to calm down in some way.. Albanians have helped me more in my life than my own.. I hope that there will be a day when we can travel freely, hang out with each other, and business would be much better;)
Last edit: 22 Nov 2022 20:27 by Masiwood123.

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22 Nov 2022 20:38 #257374 by tommylight

I hope that there will be a day when we can travel freely, hang out with each other, and business would be much better;)

About a month ago, i was having coffee with 11 of "Beogradjani" in the hotel restaurant near my house.
So you are free and welcomed to visit any time.
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22 Nov 2022 20:46 #257375 by Masiwood123
I just had in mind to ask you about the situation regarding the trip...i see that there are some tensions about the tables now, I'm constantly in the job like you, but the idea is to maybe visit in the spring, I'd really like to drink that coffee or beer. .also you are always welcome if the road brings you here...
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23 Nov 2022 00:06 #257408 by andypugh

..many people from my environment are trying to modify kuka welding robots, but without success, precisely because of mach3 limitations and those resolvers:)).

Mach3 + Resolvers really is asking to have a hard time.

LinuxCNC and resolvers works really well. My lathe has one motor that I took an encoder off of to fit a resolver :-)
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23 Nov 2022 01:22 #257413 by Masiwood123
can you briefly explain how the resolver works, how it connects to linuxcnc? the encoder is completely clear to me, I've never met the resolver and it's completely foreign to me, and I'd like to know. thanks

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23 Nov 2022 04:27 #257425 by smc.collins
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23 Nov 2022 11:05 #257448 by andypugh

en.m.wikipedia.org/wiki/Variable_reluctance_sensor
 

That's not a resolver. 

A resolver is a transformer with some parts that are stationary and some that rotate with the shaft. 
There is one primary coil which is driven with an excitation signal and then two secondary coils which provide the "sin" and "cos" outputs. 
The two secondary coils are arranged at 90 degrees so that the efficiency of the transformer coupling between them is different, and varies as the system rotates. 

There is some info here: www.siglenteu.com/application-note/resol...-waveform-generator/

But bear in mind that the waveform graph shown is rather misleading. It is showing the inputs and outputs plotted against time _and_ angle on the same axis. 

For a fixed rotor position the input will typically be a sine wave of fixed amplitude. The outputs will be two sine waves of differing amplitudes, in phase with each other and with the excitation. The amplitude of either output can be negative, though, which looks like 180 degrees out of phase. 

Interpreting the output is easier than it might seem. You just measure the amplitude of both outputs at a point in time (preferably at the peak of the excitation voltage) and take the arctan of the ratio of the two voltages to get a rotor angle. 
This is really easy with a modern microcontroller but was really rather difficult several decades ago. 
(Arduino code: wiki.linuxcnc.org/cgi-bin/wiki.pl?ResolverToQuadratureConverter
The STMBL doesn't bother with sine wave excitation, it sends a square wave and it works perfectly well. 
The Mesa 7i49 does use sine-wave excitation. 

Some resolvers are almost exactly as shown in the link above, with brushes transferring the excitation to a rotating primary coil. But most are brushless, with an input coil driving a secondary on the rotor which in turn drives the excitation primary. 

Brushless resolvers are extremely tough. All they contain is copper wires encased in epoxy. They work full of water, full of oil, when very hot or very cold. They withstand shock and vibration. 

The angular resolution depends on the interface electronics. They are an analogue device so have infinite resolution. The Mesa 7i49 has 12 bits of accuracy, equivalent to a 4096 count encoder. However many (most?) resolvers are multi-pole, typically with the same number of pole pairs as the attached motor, but in some applications very many more. 

The hard part of making a resolver is making the output linear with angle. Encoders are typically more accurate in that area, but very expensive resolvers can be very good. 


I like them :-)




 
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23 Nov 2022 11:21 #257449 by Masiwood123
Thank you for the great explanation, i am most interested in how it is connected in practice, physically and to some mesa card (only 7i49?), further, how to make the configuration for controlling in Hal?maybe it would be clearer to me if I had it physically... I'll see a friend who is struggling with it on the kuka robot, so he's trying something via arduino and mach3..

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23 Nov 2022 11:29 - 23 Nov 2022 11:30 #257452 by andypugh
Well, my Arduino thing in the link definitely worked, though not particularly well (only 8 bit resolution A to D)

(I have temporarily made this video not-private. It was getting too many questions about a not-very-good idea)
Last edit: 23 Nov 2022 11:30 by andypugh.
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23 Nov 2022 11:46 #257454 by Masiwood123
I completely understand you, explaining to people who have no basis is a waste of time.. thank you very much for this, I always ask informative questions without having a specific problem and any other way is welcome. if I have such a situation in the future, I will open a topic on that topic. Thanks Andy.

Tomo sorry for using your topic:))
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