On Sat, 29 Jan 2011, Igor Chudov wrote: > Date: Sat, 29 Jan 2011 13:51:15 -0600 > From: Igor Chudov <[email protected]> > Reply-To: "Enhanced Machine Controller (EMC)" > <[email protected]> > To: "Enhanced Machine Controller (EMC)" <[email protected]> > Subject: Re: [Emc-users] Jerky 4th axis motor rotor movement > > On Sat, Jan 29, 2011 at 8:50 AM, Peter C. Wallace <[email protected]> wrote: > >> On Sat, 29 Jan 2011, Igor Chudov wrote: >> >>> Date: Sat, 29 Jan 2011 07:43:42 -0600 >>> From: Igor Chudov <[email protected]> >>> Reply-To: "Enhanced Machine Controller (EMC)" >>> <[email protected]> >>> To: "Enhanced Machine Controller (EMC)" <[email protected] >>> >>> Subject: [Emc-users] Jerky 4th axis motor rotor movement >>> >>> I am working on getting 4th axis to work. While it does move as >> commanded, >>> it does so in a visibly jerky way. >>> >>> At first I thought that it was mechanical issue inside the rotary table, >>> such as rust, poor gear meshing, eccentricity etc. >>> >>> I took off the motor and even the lovejoy coupling. The motor, with the >>> attached resolver etc, is now completely alone, lying on a foam pad on >> the >>> floor. >>> >>> The way this system works is that the motor has a little tiny toothed >> belt >>> going to the resolver, wires from resolver go into "Resolver to >> Quadrature >>> Encoder Converter", and from there into PPMC as an input. >>> >>> The bad news is that even without anything on the shaft, it still moves >> in a >>> jerky way. >>> >>> What I mean by this is not just vibration, but the fact that it >> periodically >>> accelerates and decelerates.FASTER-slower-FASTER-slower etc. >>> >>> This shakes the whole motor as it moves. >>> >>> I have a feeling that acceleration happen at predictable angles of the >> motor >>> shaft. It is not just some random vibration from a poorly tuned feedback >>> loop. I think that it turns faster in some quadrants and slower in some >>> other quadrants. >>> >>> I know several facts: >>> >>> 1) If I apply a constant voltage to the motor, from a DC power supply, >> the >>> motor turns smoothly like a clock. >>> 2) I believe that at least over a whole number of turns, the resolver is >>> accurate. Say, if I command the RT to move by 360 degrees, it does move >> by >>> 360 degrees exactly and ends up at the perfect mark./ >>> 3) If I try to apply force to deflect motor shaft, in some positions it >> is >>> easier to move the shaft in one direction that another. The shaft springs >>> back, since there is a P factor (I and D are 0), but clearly it is harder >> to >>> turn it in one direction than another. This depends on shaft opsition. >>> >>>> From this, I conclude that this is a feedback based issue, such as the >>> resolver or resolver converter somehow being behind and ahead on >> reporting >>> its position, which leads to uneven rate of speed. >>> >>> Any ideas? >> >> Sounds like classic quadrature error in the resolver. Are you sure you have >> the resolver wired correctly? >> >> Not sure. I thought so, but I will check again. > > >> I would check that the sine and cosine output peak amplitudes are the same >> (peak amplitudes will be 90 degrees of shaft rotation apart for a 1X >> resolver) >> >> a 2 channel Scope is nice for this but if you dont have a scope a DVM will >> do >> >> > What sort of a DVM would work? What about things like Fluke handheld meters? > The frequency is 10 kHz.
almost anything should work because you are really only doing a comparison of maximum amplitudes. > > Thanks Peter. > > i > ------------------------------------------------------------------------------ > Special Offer-- Download ArcSight Logger for FREE (a $49 USD value)! > Finally, a world-class log management solution at an even better price-free! > Download using promo code Free_Logger_4_Dev2Dev. Offer expires > February 28th, so secure your free ArcSight Logger TODAY! > http://p.sf.net/sfu/arcsight-sfd2d > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ Special Offer-- Download ArcSight Logger for FREE (a $49 USD value)! Finally, a world-class log management solution at an even better price-free! Download using promo code Free_Logger_4_Dev2Dev. Offer expires February 28th, so secure your free ArcSight Logger TODAY! http://p.sf.net/sfu/arcsight-sfd2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
