On Mon, 21 Apr 2008, Anders Wallin wrote: > Date: Mon, 21 Apr 2008 09:15:55 +0300 > From: Anders Wallin <[EMAIL PROTECTED]> > 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] PID-tuning > >> I would only add I gain at the end of tuning to keep static errors and errors >> at low speeds to minimum. Enabling I gain early in tuning will only mask the >> effects of the FF1 and FF2 tuning > > OK, I will do some more tuning with only P-gain and try to get the FF1 > and FF2 gains right. > >> 1. Is it possible that you are running into current limits of your HBridge? >> (ours have little red LEDS the indicate current limit), sometimes you can >> hear the current limit in the motor if the mechanical noise lets you > > I don't think there are indicators for that on the pico drive. I will > check if the current limit can be set higher. > >> 2. Are you running out of headroom (in other words what PWM values are >> supplied when you have the large errors) I would have at least 20% of >> headroom available. > > The DAC is not maxing out during the cruise-phase. The motor will turn > around 2400 rpm at DAC=9.7 and the rapid move was around 8-8.5 on the > DAC. I don't really need that fast rapids so could go a bit lower. > The DAC signal looks trapezoidal during a move, but I guess the motor > current peaks at accel/decel ?
Yep > >> 3. What sample frequency are you using? with torque mode and straight PWM >> amps >> you will need a high sample rate than used with velocity mode servos. A >> a higher sample rate will allow higher P gains with these amps, improving >> performance. > > This is the standard 1 ms servo-thread. I could try decreasing that a > bit. Will EMC2 report about real-time delays if I reduce the servo > period too much? > Not sure, may just slow down userland stuff until the system is unuseable if set too fast. Since EMC2 is ok with 20+ KHz for step motors, 4 KHz or so should be no problem for the servo thread > > Anders > > ------------------------------------------------------------------------- > This SF.net email is sponsored by the 2008 JavaOne(SM) Conference > Don't miss this year's exciting event. There's still time to save $100. > Use priority code J8TL2D2. > http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone > _______________________________________________ > 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. ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
