On Wednesday 06 February 2008, Jon Elson wrote: >Gene Heskett wrote: >> On Wednesday 06 February 2008, Alex Joni wrote: >>>>These introduce a 50 ms delay in >>>>the feedback signal. Is this acceptable? I think, probably not. >>>> My question is this. Do I need to install encoders on the motors? >>>> Questions, thoughts, comments welcome. >>> >>>50msec is waay too much, but reading the >>>http://www.amci.com/pdfs/accessories/RD141S_rev_1.0.pdf >>>I can't find it... are you sure it wasn't 50ns ? >> >> I doubt if its that fast. With a 5khz carrier, I'd assume it takes a full >> cycle to come up with an angle and then convert, and the angle will take >> .2 milliseconds if its done in a single full cycle of the carrier. >> >> Or do I not understand how these work? > >I've studied the Analog Devices units. They have a tracking PLL >that attempts to track the velocity of the resolver. So, it >doesn't quite do a complete conversion from scratch every cycle >(or half-cycle) of the sensor excitation. It is more like it >generates an estimate of position from the PLL and then refines >the error. >Also, using the AD chip, you can set the frequency to whatever >you want. My guess is that AMTI clunker has a PIC micro with >A/D in it, and not much else, and costs them $15 to make. I >didn't see what Stuart had to pay for them. But, if that 50 ms >lag is correct, they are of VERY limited usefulness. > >Jon
I have about 6 feet of chip books (yeah, I know, today it would take 300 feet of shelves for half of them), Jon, but they don't include Analog Devices, and they are getting long in the tooth, sorta like me. :) I guess I'll have to go begging again. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) "You can't teach seven foot." -- Frank Layton, Utah Jazz basketball coach, when asked why he had recruited a seven-foot tall auto mechanic ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
