On Wed, 3 Dec 2014, Leonardo Marsaglia wrote:
Date: Wed, 3 Dec 2014 20:42:29 -0300 From: Leonardo Marsaglia <leonardomarsagli...@gmail.com> Reply-To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> Subject: [Emc-users] OT: Measuring Mitsubishi resolversHello to all again.
We're defining the hardware for the Mazak conversion and yesterday my brother and I measured the resolver signals to identify what voltage and frequency they use. I've been reading some information about resolvers and it's not too difficult to understand the way they work, anyway I have a little doubt with respect to the measurements on the excitation part. Here's what we've got from them: Between Sin + and Sin - there's 12 volts and a 4.5 khz frequency. Same thing happens on Cos + and Cos - and there's the 90?? phase shifting between the two of them. The weird thing is, when we measure the Excitation + and Excitation -, we get the 4.5 khz frequency but a voltage of about 0.3 volts. Whenever I move the axis none of this values change at all, at least that's what the digital scope showed. There's also a ground pin but I don't think that has anything to do. What I found weird is the almost none voltage on the excitation pins. I have to say the resolvers are fully functional and the machine is working ok. My doubt is why is this happening? The main goal is to measure the transformation ratio just to be sure that I can adapt these to LinuxCNC, I don't want to fit encoders because these resolvers are robust and they are working pretty well. Any ideas? Since there's a lot of people here that dealed with this before I'm sure you're going to know everything about this devices. Thanks as always for your help! -- *Leonardo Marsaglia*. That sounds like a inductosyn (sp)These have sine and cosine exitation signals (constant amplitude) and the result is a constant amplitude signal (your .3V) that is phase shifted 360 degrees every cycle (take a look at the .3V signal but sync the scope on one of the 12V signals while you turn the shaft)
These have the advantage over resolvers that the interpolation can be done without a A-D converter (you just need to time the zero crossing of the .3V oulput signal relative to one of the 12V excitation signals)
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