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. Karl ------------------------------------------------------------------------------ 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
