Re: [Emc-users] Y axis cannot calm down after movement (velocity loop in amplifier)
On Sun, 12 Sep 2010, Klemen Ozebek wrote: Date: Sun, 12 Sep 2010 21:47:39 +0200 From: Klemen Ozebek klemen.oze...@gmail.com To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Y axis cannot calm down after movement (velocity loop in amplifier) Dear all, i have the same problem on the Digitax ST drive, but my axis would try to drop under gravity. What are the possible solutions. Best regards. Klemen If you run your drives in torque mode, the Bias PID component parameter can be used to compensate for gravity. Peter Wallace -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Y axis cannot calm down after movement (velocity loop in amplifier)
snip If you had the old EMC setup where you could hit F2 and stop the positioning loop without disabling the drives, you could tell whether it is the EMC2 positioning loop or the servo amp's velocity loop that is oscillating. You can still do that by unhooking amp-enable, and only afterwards hit F2. Regards, Alex -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Y axis cannot calm down after movement (velocity loop in amplifier)
Dear all, i have the same problem on the Digitax ST drive, but my axis would try to drop under gravity. What are the possible solutions. Best regards. Klemen On Sat, Sep 11, 2010 at 9:17 PM, Andy Pugh a...@andypugh.fsnet.co.ukwrote: On 11 September 2010 20:02, Igor Chudov ichu...@gmail.com wrote: after a movement, the Y axis cannot calm down, the Y axis servo just keeps buzzing and vibrating somewhat. You could try a bit of dead-zone Is it an axis that will try to drop under gravity? -- atp -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Y axis cannot calm down after movement (velocity loop in amplifier)
I have spent a while tuning my servo loops today. One important thing to know is that my AMC 30A8 servo amplifiers have their own velocity loop based on tachometer feedback. I have had a few successes today: 1) Unset a DIP switch that limited maximum torque on the amplifiers, and increased accelerations on all axes. This will especially help with small work, like engraving, and generally complex contours. 2) Upped the maximum speeds somewhat to get 90 IPM on all axes. I may limit the speed back, just to be a little safer. I do not gain much from top speed. However, being able to accelerate quickly would be helpful. 3) Put the PC inside the control cabinet enclosure. So everything, right now, is on the pendant or in the enclosure. No more mess of PC and wires strewn all over the place. All communications between pendant and control cabinet take place through the pendant arm. But I have a problem that I just could not solve: after a movement, the Y axis cannot calm down, the Y axis servo just keeps buzzing and vibrating somewhat. Y axis is the heaviest axis on this knee mill. If I turn down P or I I start getting following errors when homing. I am not sure just what can I do. Again, the servo drives are in velocity modes and they have their own loop to control velocity of servos, based on tachometer input. Maybe I set acceleration too high? Should I perhaps take acceleration down a notch an reduce P? or I? - Igor -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Y axis cannot calm down after movement (velocity loop in amplifier)
On 11 September 2010 20:02, Igor Chudov ichu...@gmail.com wrote: after a movement, the Y axis cannot calm down, the Y axis servo just keeps buzzing and vibrating somewhat. You could try a bit of dead-zone Is it an axis that will try to drop under gravity? -- atp -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Y axis cannot calm down after movement (velocity loop in amplifier)
On Sat, Sep 11, 2010 at 2:17 PM, Andy Pugh a...@andypugh.fsnet.co.uk wrote: On 11 September 2010 20:02, Igor Chudov ichu...@gmail.com wrote: after a movement, the Y axis cannot calm down, the Y axis servo just keeps buzzing and vibrating somewhat. You could try a bit of dead-zone It is not a dead zone issue. I forgot to say something: if, after a movement, I press F2 momentarily, and then F2 again to start controlling position, this immediately calms the axis down. Is it an axis that will try to drop under gravity? Absolutely not. -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Y axis cannot calm down after movement (velocity loop in amplifier)
I forgot to add something. This bothersome humming and instability occurs only after a movement. If I press F2 to inhibit the amplifiers, and then F2 again, the humming does not restart, until I move the mill again. i -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Y axis cannot calm down after movement (velocity loop in amplifier)
On Sat, Sep 11, 2010 at 02:02:32PM -0500, Igor Chudov wrote: after a movement, the Y axis cannot calm down, the Y axis servo just keeps buzzing and vibrating somewhat. Y axis is the heaviest axis on this knee mill. Do you know yet whether it's the velocity or position loop that's oscillating? If you unhook EMC's command output, does the vibration stop? You may need to tune the velocity loop. First make sure your limit switches are working right (!) and then command a velocity step using hal or a battery. Monitor the velocity (use a scope in difference mode across the tach) and check overshoot and stability that way. Only once you have this stable can you hope to tune EMC's loop. Monitoring velocity response to a step like this will also give you a good feel for the real acceleration capability of the hardware/drives. -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Y axis cannot calm down after movement (velocity loop in amplifier)
Igor Chudov wrote: But I have a problem that I just could not solve: after a movement, the Y axis cannot calm down, the Y axis servo just keeps buzzing and vibrating somewhat. Y axis is the heaviest axis on this knee mill. If I turn down P or I I start getting following errors when homing. I am not sure just what can I do. Again, the servo drives are in velocity modes and they have their own loop to control velocity of servos, based on tachometer input. Maybe I set acceleration too high? Should I perhaps take acceleration down a notch an reduce P? or I? No, acceleration has nothing to do with loop stability, except that it excites any resonances in the system. If you had the old EMC setup where you could hit F2 and stop the positioning loop without disabling the drives, you could tell whether it is the EMC2 positioning loop or the servo amp's velocity loop that is oscillating. But, I would probably guess it is the velocity loop. What you want to do is either increase damping on the amplifier or reduce BOTH the command gain and the tach feedback gain. If the oscillation is in the velocity loop, nothing you do in EMC will fix it. Jon -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
