On 8 August 2010 04:35, Igor Chudov <ichu...@gmail.com> wrote: > Say, I say S3000 and drill. Then I change tool to a tap and say S300 > and rigid tap. To accomplish that, EMC would actuate SPEED DECREASE > solenoid and wait until the output speed, as reported by the encoder, > approximately equals the commanded speed.
Rigid tapping is where a rather complicated behaviour is likely to be seen. Assuming the stop and reverse is done by the VFD, as soon as your varispeed control structure sees the speed dropping is it likely to try to try to keep the speed up and the two speed control systems are likely to end up fighting. A VFD is a much faster-reacting system than the Varispeed, and less prone to wear. However, the Varispeed gives increased torque at lower speeds, so you really should use both. You could potentially use the Varispeed as a gearbox, perhaps fitting a home-made encoder quadrant or disc to some part of the actuator and then automatically driving it a given position, or having input and output encoders and settting an absolute speed ratio dependent on spindle speed request then using a PID and the VFD for fine-tuning, load compensation etc. Ideally you would want to do this purely on the basis of the active "S=" parameter, rather than on the spindle speed output pin, which varies during rigid tapping moves. I am not aware if this value is available separately to HAL. Anyway, you can operate the solenoids fairly easily using two comparator functions in HAL. http://www.linuxcnc.org/docview/html//man/man9/comp.9.html loadrt comp names=over,under . . addf over servo-thread addf under servo-thread setp over.hyst 25 setp under.hyst 25 net motion.spindle-speed-out => over.in0 under.in1 net {whatever your speed signal pin is called} => over.in1 under.in0 net over.out => {speed reduce pin} net under.out => {speed increase pin} -- atp ------------------------------------------------------------------------------ This SF.net email is sponsored by Make an app they can't live without Enter the BlackBerry Developer Challenge http://p.sf.net/sfu/RIM-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
