Brian, If you have a closed loop system and are using scales then using screw comp really doesn't make any sense since the outer loop is closed to the scales.
Screw comp only makes sense if you are relying on the screws accuracy. You will be relying on the scales accuracy, not the screws. You won't care how accurate your screws are with the scales you have. Backlash can be done at least two different ways within EMC. You can do it the way you described or you can simply specify a backlash value for each axis. I think there is also a third method which I can't remember. If your backlash is not too severe, and you are closing the position loop with the scales, the position loop might be able to compensate for your backlash also. I'd try it. I already know that the closed loop setup with EMC2 works fine. The machine I did a few months ago is was running two shifts the last I heard - non stop and it is very accurate due to the closed position loop. Dave On 8/8/2010 11:00 PM, Brian wrote: >> And that's what I SIMPLY don't understand. I have two servo-controlled >> machines. >> >> Jon >> > Jon, > > EMC adds the screw compensation to the measured value from the > encoder before it is interpreted as actual joint position. Therefore, > if I want to use screw comp and scale feedback at the same time, it > wont work. > > If you have any further doubt as to how EMC works, you should > investigate HAL for yourself, to avoid any further assumption. > > Dave, > > When using a screw comp table, backlash correction is incorporated > by default. It is the difference between the forward and reverse > screw maps. > > Brian > > ------------------------------------------------------------------------------ > 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-developers mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-developers > > ------------------------------------------------------------------------------ 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-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
