Igor Chudov wrote: > Think about it this way: the way I worked with a MANUAL crank is, when I > needed to move the knee, I would crank it, watch the dial, and stop where > appropriate. > > After this, I let go of the crank. I do not obsessively hold the crank, > trying to prevent any movevent (like EMC does), and specifically I do not > keep pushing the crank to move that last thousandth, while not quite pushing > enough to really make the move. I just get it to where I am satisfied, and > let go of the handle. > > What EMC does instead is, it keeps applying the PID algorithm to the motor, > and tries to push it "the last thousandth", without actually geting there, > so the motor just heats up from current passing through it. > > The knee ACME screw is self locking. > > How can I make EMC do the same, just "let go" after it gets to the right > place? > > You really can't do this with an axis in EMC, as far as I know. If you had a linear encoder on the knee, you could read that into EMC2 and use it for whatever purpose you want. You could rig a switch to the servo drive and set the following error tolerance so that EMC would accept and display it as an axis, but not actually be able to control it. But, if you can jog it or command it with G-code, then it needs to be controlled all the time, unless you do something fairly different from normal EMC use.
I think the real problem is that the motor is severely underpowered for the load, and is being forced into the peak torque range under standstill conditions, which is an abusive situation, as you have discovered. Either a stronger motor or a greater reduction ratio is needed so the motor is safely within the continuous torque rating when standing still. This may take a really big motor for such a heavy knee. Jon ------------------------------------------------------------------------------ Free Software Download: Index, Search & Analyze Logs and other IT data in Real-Time with Splunk. Collect, index and harness all the fast moving IT data generated by your applications, servers and devices whether physical, virtual or in the cloud. Deliver compliance at lower cost and gain new business insights. http://p.sf.net/sfu/splunk-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
