On Sun, 06 May 2012 07:33:39 -0700, Karl Cunningham wrote: > On 05/04/2012 11:22 PM, EBo wrote: >> On Fri, 04 May 2012 22:44:32 -0700, Karl Cunningham wrote: >>> On 05/04/2012 07:26 PM, Jon Elson wrote: >>>> I have a dynamic signal analyzer, but have not had stellar results >>>> using it. >>>> But, it seems that one could build such a thing in HAL. You'd >>>> need >>>> a swept >>>> sine wave generator to stimulate the system, and record the >>>> response >>>> of >>>> the system, both amplitude and phase to the stimulus. Just add >>>> the >>>> sine >>>> wave excitation to a constant position and feed this to the PID, >>>> and >>>> record position. Then, feed that to a Fourier analysis. >>> >>> Drawing on another one of my hobbies... Here is a description of >>> some >>> techniques for this sort of thing, including a link to a writeup >>> from >>> HP >>> (from the 1960s) on using their wave analyzer. >>> >>> http://bnordgren.org/seismo/lpmeas3.pdf >>> >>> This has to do with seismometer design, but I think the principles >>> are >>> very similar. >>> >>> I have a few geophones (mentioned earlier in this thread) which >>> might >>> be >>> usable for collecting vibration data. I don't have a good >>> high-sample-rate ADC, but perhaps some scope traces would suffice. >> >> First off. Thank you for the reference!!! This is a great >> information >> and a better idea ;-) Added with a little of simple statistics on >> top >> of fft/wavelet/etc. and I think a lot of mileage can be gained if I >> do >> not miss my bet... >> >>> If someone has any specific tests they would like done with this on >>> a >>> 3-axis knee mill, I could give it a go. >> >> Where are you located? I'm currently working as a contractor at >> NASA's >> Goddard Space Flight Center, and currently have access to an old >> MaxNC-10 and some newer electronics (like a Gecko-520+motors AND >> Li's >> FPGA NURBS beta hardware _ motors + drives, etc.) So if we are >> within a >> couple hundred miles of each other then maybe we can trow some tests >> together... > > I'm a bit further away -- San Diego. > > If this can be made to work, it's possible these techniques could > also > be used to help tune PID coefficients. Or at least point out where > there > is marginal loop stability.
Sitting down together at a machine might be a bit logistically challenged... We could meet half way in between when I travel back to central Lousiana, but still logistically challenged. It is also to bad that I no longer have access to the 14bit 300Ms/s ADCs I got to play with a little in the past. That would probably tell us a little bit ;-) But seriously, I think it would be nice if we could come up with some various instruments and examples as an add on toolbox. EBo -- ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
