On Thu, 1 May 2014, Curtis Dutton wrote: > Date: Thu, 1 May 2014 18:56:23 -0400 > From: Curtis Dutton <curtd...@gmail.com> > Reply-To: "Enhanced Machine Controller (EMC)" > <emc-users@lists.sourceforge.net> > To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> > Subject: Re: [Emc-users] Leadshine ACS806 - Large f-error at higher speeds - > what is acceptable? > > Thanks to everybody for the information. If anything it helped me > understand the nature of servos better as I've been sitting here tweaking > the machine. > > I tried 2 experiments to see if I could get better results. > > #1. Give it 80Volts: I hooked the driver up to an 80v PS. The drive clearly > had more power, however the following error is exactly the same behavior. > > #2. Run the motor with no load: I disconnected the motor drive belt. > Re-tuned the servo and then started running it in linux cnc. Net result... > exactly the same behavior. > > The higher the velocity, the more the error increases, and it appears to be > completely linear.
Can you add any I term to the drives position control loop? Enough I term should pull the following error to an average of 0 on a long slew > > > So it has something to do with some sort of lag in the servo driver. I'll > be emailing leadshine with my fingers crossed hoping they can help. > > For what the servo is driving, seat of the pants says that the servo has > more torque then the old stepper did, so the machine should behave better > than it used to. > > Thanks! > Curt > > > On Thu, May 1, 2014 at 2:26 PM, Gene Heskett <ghesk...@wdtv.com> wrote: > >> On Thursday 01 May 2014 13:42:08 Curtis Dutton did opine: >> >>> Ok this makes sense. Thanks all for your explanations. I guess I just >>> wasn't sure what was reasonable behavior and what wasnt. >>> >>> So if the motor is rated for 36v, and the drive is rated for 80 volts >>> max. How much voltage can I get away with delivering to the drives >>> without damaging equipment? >>> >>> >>> Thanks, >>> Curtis >> >> I, as an electronics type, would look at it from the motors rated currant >> viewpoint regardless of the family of motor. >> >> The motor more than likely has permanent magnet fields, and allowing more >> currant than about 1.25x the nameplate rating (based on my reading on the >> subject but I don't have an URL's to offer) gets you into a magnetic >> territory where the field magnets can be damaged by reducing their magnetic >> strength, and its an instant and permanent effect. >> >> The same effect applies to steppers, usually at currants above 1.25x >> nameplate. >> >> Applying an 80 volt supply to a 32 volt rated motor seems like it would be, >> if not currant limited in the driver, playing with fire. I would have to >> assume they said that assuming a condition where it could spin freely, >> letting its counter EMF control the current and therefore the resultant >> magnetic field. >> >> This isn't normally a concern with steppers because the 10 to 30x over >> voltage is just normal standard operating voltage for them. The drivers >> chopper limits on the currant are many times more important to the long >> term health of the motors. I see no reason not to apply much the same >> thinking to PM field servo motors. Any difference is in where the magnets >> are, the steppers magnet is the rotor, where a brushed servo has the magnet >> in its stator. But its still the strongest magnet we know how to build in >> production quantities. >> >> Now, in servo's I'll have to plead the big dummy because in brushless, hall >> effect commutated motors (BLDC?), it seem like a 3rd phase of drive to what >> is basically a 3 phase wound stepper motor frame assembly, meaning the >> rotor is the PM, would this not also apply? >> >> Or do they have something even more complex for the "BLDC" format? I am >> not using them, so I've not spent a lot of time researching how they are >> built. >> >> My understanding is quite incomplete for those, and is not clarified a bit >> by having so many available mappings in the BLDC driver. I suspect the >> reason for that boils down to a profound lack of a standard way of marking >> the motors leads as to phase & polarity, making the builder try every >> combination until he hits the right one that just happens to be correct for >> the wire hookup sequence he used? >> >> Is there a URL to read that would help me understand that Jon? >> >>> On Thu, May 1, 2014 at 10:44 AM, Jon Elson <el...@pico-systems.com> >> wrote: >>>> On 05/01/2014 06:22 AM, andy pugh wrote: >>>>> On 30 April 2014 19:37, Curtis Dutton <curtd...@gmail.com> wrote: >>>>>> The motor is a 130W motor >>>>>> 1.5mm at around 12000mm/min. >>>>> >>>>> That seems like a very small motor, and a very fast travel. >>>>> >>>>> Is it possible that the motor is simply running out of steam? >>>> >>>> Generally when the drive runs out of available voltage >>>> the following error very suddenly grows without bound. >>>> So, you can be at 500mm/min with error of .01mm, >>>> and then at 550mm/min the error rises continuously >>>> because full voltage applied to the motor is only >>>> giving you 520mm/min, to give an example. >>>> >>>> So, having the following error increase only a modest bit >>>> at higher speeds may indicate the drive just has a >>>> constant time lag in the internal loop. Or, it may >>>> be a torque limit, where the 130 W motor is nearly >>>> maxed out on current driving the axis at 12 m/min. >>>> Those conditions might cause a bounded error >>>> that increases roughly proportionally to velocity. >>>> >>>> Jon >>>> >>>> >>>> ---------------------------------------------------------------------- >>>> -------- "Accelerate Dev Cycles with Automated Cross-Browser Testing - >>>> For FREE Instantly run your Selenium tests across 300+ browser/OS >>>> combos. Get unparalleled scalability from the best Selenium testing >>>> platform available. Simple to use. Nothing to install. Get started >>>> now for free." http://p.sf.net/sfu/SauceLabs >>>> _______________________________________________ >>>> Emc-users mailing list >>>> Emc-users@lists.sourceforge.net >>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>> >>> ------------------------------------------------------------------------ >>> ------ "Accelerate Dev Cycles with Automated Cross-Browser Testing - For >>> FREE Instantly run your Selenium tests across 300+ browser/OS combos. >>> Get unparalleled scalability from the best Selenium testing platform >>> available. Simple to use. Nothing to install. Get started now for >>> free." >>> http://p.sf.net/sfu/SauceLabs >>> _______________________________________________ >>> Emc-users mailing list >>> Emc-users@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/emc-users >> >> >> 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) >> Genes Web page <http://geneslinuxbox.net:6309/gene> >> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS >> >> >> ------------------------------------------------------------------------------ >> "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE >> Instantly run your Selenium tests across 300+ browser/OS combos. Get >> unparalleled scalability from the best Selenium testing platform available. >> Simple to use. Nothing to install. Get started now for free." >> http://p.sf.net/sfu/SauceLabs >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > ------------------------------------------------------------------------------ > "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE > Instantly run your Selenium tests across 300+ browser/OS combos. Get > unparalleled scalability from the best Selenium testing platform available. > Simple to use. Nothing to install. Get started now for free." > http://p.sf.net/sfu/SauceLabs > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > 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. ------------------------------------------------------------------------------ "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE Instantly run your Selenium tests across 300+ browser/OS combos. Get unparalleled scalability from the best Selenium testing platform available. Simple to use. Nothing to install. 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