> > Now if the motor has an encoder LinuxCNC could read the position every > 1ms > > and make it a host based closed loop system. And I get the appeal. > > But people are also using LinuxCNC with a BOB and Open Loop Steppers > > without an encoder. > > So it sounds like the feedback is missing there. > Some setups, have "synthetic" feedback from counting stepper > pulses. >
But what's the point of that? Isn't that just faking the position information? It seems like LinuxCNC could calculate that position even itself (time+velocity => position) It's just the position the motor should be at - not the position the motor really is. I make a hardware stepper board that has step generators > that are sent a velocity, and counters that can count the > steps or read an encoder. So, by flipping a switch on the > board, you can select open-loop or closed-loop mode. The > position counter is read back by the computer and LinuxCNC's > PID component computes the next velocity to send out, based > on the difference between commanded and actual position. I > also make a servo board that is very similar to the above, > except that it sends a PWM pulse train to the drives > proportional to desired velocity. The rest of the setup is > the same. > That's the "Universal Stepper Controller"? cheers, Torsten _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
