The trajectory planner obeys the MAX_ACCELERATION, the problem is when you throw backlash compensation in on top of it. The Step generator then needs the extra headroom in STEPGEN _MAXACCEL to catch up with where the trajectory planner is commanding it to be plus the backlash take up move. So the real problem is that the trajectory planner doesn't account for backlash, that is something added in on top of it's calculations.
Todd Zuercher P. Graham Dunn Inc. 630 Henry Street Dalton, Ohio 44618 Phone: (330)828-2105ext. 2031 -----Original Message----- From: John Dammeyer <jo...@autoartisans.com> Sent: Thursday, March 04, 2021 3:41 PM To: 'Enhanced Machine Controller (EMC)' <emc-users@lists.sourceforge.net> Subject: Re: [Emc-users] Following Error Joint 2 [EXTERNAL EMAIL] Be sure links are safe. > From: Les Newell [mailto:les.new...@fastmail.co.uk] > > I'm going to guess that low-level I/O error is a general > > _Following_Error_Joint_2_? > > No. It is a different error. I can't remember the exact wording but I > have seen it before. > > The following error message is correct. With steppers you have two > acceleration settings. There is the joint acceleration which is used > by the trajectory planner and the stepgen acceleration. > STEPGEN_MAXACCEL is used to simulate the physical limits of the > stepper and it's load. It's a simulated equivalent to to a servo motor > running out of torque. If the trajectory planner commands a higher > acceleration than STEPGEN_MAXACCEL the stepgen will not be able to > keep up and you get a following error in exactly the same way you would on a > servo system that ran out of torque. > > Les That doesn't explain why, if STEPGEN _MAXACCEL is set to 125% of MAX_ACCELERATION that the trajectory planner or Stepgen tries to use a number larger than that. It's like saying I know you have a 1 gallon pail but because I have 1 gallon in my pail I'm going to pour it into yours. Too bad it overflows when I pour two of my pails into one of yours. You should have had a 2 gallon pail. What the heck is the point of a parameter like STEPGEN_MAXACCEL or MAX_ACCELRATION if it can be broken so easily. Just confused here. John _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
