On Tue, 7 May 2013, Roland Jollivet wrote: > Date: Tue, 7 May 2013 15:41:39 +0200 > From: Roland Jollivet <[email protected]> > Reply-To: "Enhanced Machine Controller (EMC)" > <[email protected]> > To: "Enhanced Machine Controller (EMC)" <[email protected]> > Subject: [Emc-users] Creep in X axis > > On 7 May 2013 07:17, Marius Liebenberg <[email protected]> wrote: > >> New machine Stuart. It is a custom machine that processes structural >> beams. the machine is 30m long with 5 axis and many pneumatic controls. >> The x axis is the material that is moved and not the machine. >> > > Hi Marius > > Have you tried doing a very slow movement, like at 50mm/min or even slower. > > Place a ruler on the table and compare the DRO to physical movement. Check > again at the halfway mark, then again at the end. You can then determine > whether the error is at start, or at end, or in scaling. > > Also, if the output, possibly, from the encoder is not exactly 50/50, it > could accumulate an error at anything faster than slow stepping. > And maybe this is not applicable, but is the index pulse mathematically, or > logically involved in the distance calculation. It could be being > subtracted? in the computation of position. > > Regards > Roland > ------------------------------------------------------------------------------
If the drives encoder output cable was wired wrong so that index and one of the A, /A, B, /B lines were swapped, It might cause strange behaviour like this. Also with a 3500 count/mm scale and 20000 mm/m the count rate is 1.16 MHz. Can the drive actually generate good quadrature at that rate? If the Drive has quadrature output hardware hardware or a FPGA this should be easy, but if this is being done by a DSP, its quadrature is probably pretty lumpy at this rate. This should be testable by doing a motion at say 1/2 the maximum speed. If the error goes away, you might try lowering the drives quadrature output resolution. > Learn Graph Databases - Download FREE O'Reilly Book > "Graph Databases" is the definitive new guide to graph databases and > their applications. This 200-page book is written by three acclaimed > leaders in the field. The early access version is available now. > Download your free book today! http://p.sf.net/sfu/neotech_d2d_may > _______________________________________________ > 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. ------------------------------------------------------------------------------ Learn Graph Databases - Download FREE O'Reilly Book "Graph Databases" is the definitive new guide to graph databases and their applications. This 200-page book is written by three acclaimed leaders in the field. The early access version is available now. Download your free book today! http://p.sf.net/sfu/neotech_d2d_may _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
