On Sat, Jan 29, 2011 at 6:38 PM, Jon Elson <[email protected]> wrote:
> Igor Chudov wrote: > > 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. > > > > > OK, use Halscope to look at ppmc.0.encoder.nn.delta and see if that is > moving smoothly, > or perhaps has jagged velocity changes. I am thinking that there is > something wrong with > the reading of resolver position. Unlike an optical encoder, which can > just lose pulses, > the resolver converter will always "catch up" at some time, so it can > give an uneven conversion > of velocity while never losing long-term position. > > Jon, assuming that the jerky movement of the motor is due to bad reading of resolver, EMC2 may think that the motor actually moves smoothly. I am going to dig in depth tonight if I can. > If you are still using the old cables with the common point between the > two stator windings, > that could be the cause, by mixing she sin and cos signals. Otherwise, > definitely disconnect the > stator signals and hook to an oscilloscope. No, I am using two pairs for sine and cosine. Each pair is separately shielded. I grounded their bare grounding wires together in the middle between sine and cosine terminals. > Turn the motor until the > signal on one of the > stator windings reaches a maximum and then see if it is close to 3.6 V > P-P. If not, then adjust > the jumpers on the resolver converter board to get as close to 3.6 V P-P > as you can get. > > Jon, yes, I will try to do that. Time to get my oscilloscope out and other forms of heavy artillery. i9 > Jon > > > ------------------------------------------------------------------------------ > 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 > ------------------------------------------------------------------------------ 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
