On Sun, 17 Apr 2016, Gene Heskett wrote:
> Date: Sun, 17 Apr 2016 18:57:59 -0400
> From: Gene Heskett <[email protected]>
> Reply-To: "Enhanced Machine Controller (EMC)"
> <[email protected]>
> To: "Enhanced Machine Controller (EMC)" <[email protected]>
> Subject: [Emc-users] g33.1 fine tuning.
>
> Greetings;
>
> I am being plagued with joint 2 following errors that are manifested at
> about the time that Z is reset from its up overshoot, back to the
> original starting position.
>
> The problem comes down to the speed limit imposed by that 1600 oz/in 3.5
> amp Z motor.
>
> It, with the setup I have at the moment, seems to be triggered at the
> stop point of the upper reset to starting position after the Z is
> unlocked and run back to the original starting point, compounded by
> neither of the axis sliders to set limit speeds having any effect at all
> on the Z speed commanded by motion at this run it back down stage, and
> while I have it running ok with very little oscillation visible on the
> hal scope, about 1 in 100 cycles there is a big blast of ringing, and
> about once in 25 instances of that, the ringing will cause an axis 2
> following error.
>
> My thinking runs like this. Since it is locked to the spindle, moving
> one thread of Z for every turn of the spindle, forming the speed/dir
> command into the spindles PID to restrict its maximum speed with the
> maxv of a limit3, and a similar value fed into maxa, generates a
> nice "sine squared" waveform, effectively controlling the rate of change
> when it is moving the Z at maximum turn around speed. This seems to
> help, but its quite spindle speed sensitive, as in if its working well
> at 500 revs, it all goes in the toilet at 400 or at 600 spindle revs.
>
> The last thing I tried, and which appeared to stabilize it quite a bit,
> was to "setp pid.z.Dgain -0.001."
>
> But is that the proper way? I'd druther not be restricted to a spindle
> rpm that results in a 14.5 to 16 ipm Z speed, about 1/3rd of what it can
> move. Said another way, the optimum spindle revs will obviously go up
> and down with how fine a thread were boring.
>
> PID.z has the usual settings for a 4 kilohertz servo thread, Pgain=4000,
> Igain=0.0, FF0=0.00, FF1 = 1.0, and FF2=0.00025, and now Dgain = -0.001.
> Backlash is about 0.00075 atm.
>
> Ideas anybody? Time to try the atpid?
>
> Thanks.
>
> Cheers, Gene Heskett
> --
> "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>
>
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Try doubling the stepgen maxaccel setting
Peter Wallace
Mesa Electronics
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Find and fix application performance issues faster with Applications Manager
Applications Manager provides deep performance insights into multiple tiers of
your business applications. It resolves application problems quickly and
reduces your MTTR. Get your free trial!
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