On Mon, 10 Aug 2015, Nicholas Mc Guire wrote: > Date: Mon, 10 Aug 2015 08:40:02 +0200 > From: Nicholas Mc Guire <der.h...@hofr.at> > Reply-To: EMC developers <emc-developers@lists.sourceforge.net> > To: EMC developers <emc-developers@lists.sourceforge.net> > Subject: Re: [Emc-developers] research on optical encoders > > On Sat, 08 Aug 2015, Peter C. Wallace wrote: > >>> >>> I think the trick the Resolute encoder uses is this: the image is captured >>> in >>> a perhaps sub microsecond flash of the LED, and then the "image" can be >>> shifted out of the sensor at a leisurely rate. The specifications sort of >>> suggests this (very fast capture (ns) time, but only multi KHz maximum >>> update >>> rate) >>> >>> Peter Wallace >>> Mesa Electronics >>> >> >> They may in fact use a laser for illumination as AFAIK you can get higher >> peak >> power with a pulsed laser than a LED. These are in the $30 region for 75W >> peak >> 40 ns pulse width, not much vibration or motion blur in 40 ns :-) >> > > the problem is not the vibration in the 40ns > but that the recorded encoder image is more or less > a random position within the vibration range of > the device + vibration of the laser - I was thinking > about compensations like done with satelite images > where multiple pictures are taken and then the signals > are compensated by filtering out szintilation effects > > If the actual sampling is in the multi kHz range only then > that would be well in the modes that such systems can have > and one - worst case - would have the full vibration in > the positional information. Just wonder if there are any > detection algorithms that look into such issues. Naively > one could do a fft on the position data under the assumption > that motion should be constant/known-trajectory and that > could reveale such vibration/aliasing induced errors. > >> http://www.osram-os.com/osram_os/en/products/product-catalog/laser-diodes/high-power-laser-diodes/pulsed-laser-diodes/hybrid-pulsed-laser-diodes/index.jsp >> >> ( thank you Harold Edgerton ) >> > thx! > hofrat
Not sure vibration in the 10 KHz and up range is a serious problem here as it takes significant energy to get even tiny displacements at 10 KHz or so in the heavy mechanics used with precision encoders. Motion blur _is_ an issue but this is solved by the strobed lighting. > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers > Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
