On Wed, Sep 15, 2010 at 09:07:28AM -0500, Chris Radek wrote: > > It looks like the axes can't accelerate as fast as you are requesting.
After looking at it again, this comment is wrong. The problem is that your tuning is completely wrong for velocity mode. With P only, you're commanding a velocity proportional to the position error. This is not at all what you want. Setting this up is a little tricky. Your amps probably have their gain set so that something around 9v is the rapid speed for the axis. You need to set your ppmc dac scaling so a commanded rapid velocity (in inches/second) gives this 9 volts. Looks like on ppmc, duty cycle = value / scale. So with value 8 (rapid speed from your ini) if you want duty cycle 0.9 your scale should be 8.89. Then you should set FF1 = 1 to make the pid output equal to the commanded velocity (plus or minus the adjustments that will come from P and D as you settle on a good tuning.) Once you have your scale set correctly you will get better following but there will probably be a little steady following error that is proportional to the velocity. You can adjust this by adjusting FF1, scale, or (my preference) the tach gain knob on the amp. This will fine tune that 9 volts to be your rapid speed. Everything else will fall into place then. Chris ------------------------------------------------------------------------------ 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
