Hi Jon; Answers below. On Thu, Feb 3, 2011 at 9:32 PM, Jon Elson <[email protected]> wrote:
> Don Stanley wrote: > > Hi All; > > I am attempting to configure EMC2 10.04.06 to control RPM > > on a 60 HZ AC generator. > > > > The basic approach is: > > -Set the steps per inch to the number of AC cycles per day. > > -Monitor the AC frequency into phase A of a HAL encoder. > > -Feed the encoder output into the axis and PID feedback. > > -Feed the axis motor-pos-cmd to stepgen position-cmd. > > -Feed the stepgen out through the paraport to a stepper motor driver. > > > > This seems to work in general but there are two problems I > > have not been able to pin down. > > 1- The PID error is a sawtooth shape causing the throttle > > stepper motor to quiver at 60 HZ. > > A HAL Scope image is available at > > http://imagebin.org/135986 > > > > > The sawtooth appears to be happening at 16.5 ms, which is one 60 Hz cycle. > Perhaps that is significant. Also the steps in the sawtooth are one millisecond, the thread rate. > What is the velocity coming out of the > encoder counter > component? The encoder.1.velocity is showing 1.16nnnn e-5 to 1.18nnnn e-5 . > Does it waver at all? Yes it does, but no surprise considering the test environment. To protect the generator and engine from runaway bug damage, I have the throttle drive motor connected to a variable output transformer connected to an electric drill driving a permanent magnet motor to produce the AC signal into the encoder input. Until I get the maximum catchup RPM under control I can't consider going to the live generator. On start up EMC2 is driving the generator to 120 HZ to get the target position in sync. > If all these calculations are > performed in arithmetic > scaled to days, you may be looking at the limits of binary precision. I > notice your > sawtooth is fluctuating by much less than 1 millionth of a unit, roughly > 2 x 10 ^ -7. > I have questioned that possibility but have not got the round TUIT. But, if I can't get the over speed under control I may have to abandon this approach. Any suggestions appreciated. Thanks Don > > Jon > > > ------------------------------------------------------------------------------ > The modern datacenter depends on network connectivity to access resources > and provide services. The best practices for maximizing a physical server's > connectivity to a physical network are well understood - see how these > rules translate into the virtual world? > http://p.sf.net/sfu/oracle-sfdevnlfb > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ The modern datacenter depends on network connectivity to access resources and provide services. The best practices for maximizing a physical server's connectivity to a physical network are well understood - see how these rules translate into the virtual world? http://p.sf.net/sfu/oracle-sfdevnlfb _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
