On 11/08/2015 09:54 PM, TJoseph Powderly wrote: > moog or pegasus. brands, those are the big names. > they were used to move really heavy cast iron slides, often dovetail. > > messy ( plan on leaks and kitty litter ) > the hydraulic supply tops up the volume from a reservoir that you keep full > these are really really beefy systems. > > the internal of the valve ( generic name spool valve) is like a voice coil, > i doubt you can move the mass as fast as you can shake that spool. > > think linear scales to track the slides not the piston. > > In fact, they typically add a dither to the servo command to the valve to keep the spool floating. otherwise, there can be a bit of a jerk when it first starts to move. Allen-Bradley's hydraulic output module adds a 400 Hz triangle wave to the DAC output for this purpose.
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