Andy Holcomb wrote: >What resolution of encoders have should I use, my first thought is as >high as possible, is my logic wrong? > > Heh. I didn't see any logic in that statement, just a conclusion ;)
In general, higher resolution is better. It will increase cost though, both because very high resolution encoders are more expensive, and because they will require hardware to read them at any significant speed. Here's what I'd do to figure out what resolution encoder you need. First, you should know the distance the axis in question moves per turn of the encoder shaft (this may not be the same as the servo shaft). Next, decide the effective accuracy you'll want from the machine. In general, you'll want the feedback resolution to be greater than the desired effective resolution - at least twice the resolution, and often people say 10 times (at least in the measurement wotld). The last thing to think about is whether the machine itself is built to the tolerances you want - no point getting 1 micron encoder counts with acme screws ... Once you have all that info, it's easy to figure out the resolution you need/want: encoder resolution = (steps per inch or mm) / (shaft revs per inch or mm). so 10 revs/inch at 50000 steps/inch resolution = 50000/10 = 5000 counts, or a 12-13 bit encoder (4096 or 8192 counts/rev, respectively). Hope this helps. Sorry I can't be more specific regarding this machine. - Steve ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
