On Sun, 6 Apr 2008, Jon Elson wrote: > Date: Sun, 06 Apr 2008 20:06:27 -0500 > From: Jon Elson <[EMAIL PROTECTED]> > Reply-To: "Enhanced Machine Controller (EMC)" > <[email protected]> > To: "Enhanced Machine Controller (EMC)" <[email protected]> > Subject: Re: [Emc-users] PID tuning / Inverse-deadband > > Anders Wallin wrote: >> Hi All, >> >> did some initial PID tuning with a DC servo motor on the bench (no load) >> today. I'm using Jon Elsons servo amplifiers with a m5i20 (hostmot >> config with 100MHz clock to enable 50 kHz PWM). >> >> Some hal-scope screenshots here: >> http://www.anderswallin.net/2008/04/pid-tunig/ >> (click the pictures for better views) >> >> I found the PID-loop to be slightly 'squishy' when twisting the axle by >> hand from the set-point, so I added an inverse deadband component which >> cures this problem: > Really, just more gain should help this. The inverse deadband > just makes it more jittery, I'd think.
Actually anything you can do to linearize the torque/PID function including inverse deadband is a good thing, as long as you dont have so much that you get positive feedback. Feed forward is your friend, feedback is good but its always too late... I've been dealing with Deadband (and inverse deadband) in the current control loop of our new 8I20 3 Phase BLDC torque Amp (for weeks it seems). The fast switching speeds of MOSFETs really spoil you, With IGBTs the carrier crossover deaband is a killer... >> http://www.anderswallin.net/2008/04/idb-inverse-deadband-component-for-emc2/ >> >> Would be nice to hear from others with the same kind of setup on what >> tuning methods you use and whether you found 'inverse deadband' to be >> required. The end result was a FE of +/- 32 encoder counts - would that >> be typical? > If your encoders have sufficient resolution, you should be able > to do a lot better. I get down to about 5 encoder counts of > peak error when accelerating to 60 IPM or so on my mini-mill. > > Jon > > ------------------------------------------------------------------------- > This SF.net email is sponsored by the 2008 JavaOne(SM) Conference > Register now and save $200. Hurry, offer ends at 11:59 p.m., > Monday, April 7! Use priority code J8TLD2. > http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone > _______________________________________________ > 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. ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Register now and save $200. Hurry, offer ends at 11:59 p.m., Monday, April 7! Use priority code J8TLD2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
