Unfortunately I'm in Victoria, BC, the equipment is down south somewhere. The mechanical engineer was convinced it was software so there was very little support in trying to get the problem solved.
A senior engineer (as in not a millennial) was down a little later and he took apart the right angle drive from the motor to the lead screw and found all the binding areas that resulted in the mechanical locking. Once the mechanism moved freely there was no issue as far as I know. https://www.sonceboz.com/sites/default/files/medias/standard-products/data-sheets/hybrid-stepper-motor/version2018/8863R1000industrial-4.0.pdf It's a nice motor and easy to work with using CANopen messaging. John > -----Original Message----- > From: craig [mailto:[email protected]] > Sent: November-15-18 11:59 PM > To: [email protected] > Subject: Re: [Emc-users] Accuracy of step/servo > > could this possibly be a rigidity or mounting movement issue?��� Have > you tried to move it back and forth a number of times to see if error is > add up or stay bounded? > Craig > > On 11/4/2018 3:17 PM, John Dammeyer wrote: > > This discussion of servo gear heads brings up an interesting question for > > me. > > > > I've been working on a system that has a CANopen controller Step/Servo > with > > integrated encoder. The motor turns a lead screw (10 TPI) which moves a > > scissor jack type mechanism. We have an extra external encoder mounted > on > > the screw to be able to determine where the screw is on power up since it > > could be anywhere. The step/servo is configured to have 200 steps per rev > > which still works out to 0.0005" of linear movement. More than accurate > > enough. > > > > What we're finding is that occasionally, a CAN message with a Move to > > Position command of 2549 steps moves one or two less steps than it should. > > To position 2547. The status CANopen message does not report move > complete. > > Our software times out waiting for that move complete message after 15 > > seconds. The actual move up to that position is only 4 seconds. So the > > step/servo has over 10 seconds to move 1.8 to 3.6 degrees (2 steps) to reach > > the end of move position. > > > > I've been told to ignore this and when the external encoder is close enough > > go on with the rest of the motion profile. In other words, ignore that the > > motor isn't reaching the target position. > > > > If I allowed my Electronic Lead Screw to not always reach the end position I > > think I'd have users > > complaining. > > > > The process isn't severely compromised by that two step shortfall. So we > > can go on by ignoring motion complete. But this has all the appearance of > > something that will fail worse later on if not addressed. > > > > Am I being too fussy? > > > > Thanks > > John > > > > > > > > > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
