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  1. #1
    Join Date
    Jan 2005
    Posts
    15362

    Re: Jerk Control in machines

    Quote Originally Posted by ihavenofish View Post
    That fanuc article is from 2012 and still considered valid methodology although the exact feature naming has changed. It is still a trajectory planning algorithm and has nothing to do with the drives.

    ---------

    Features
    Whereas the rate-of-change of velocity is referred to as Acceleration, the rate-of-change of acceleration is technically
    known as Jerk. Jerk is therefore the third derivative of Position, with Acceleration the second and Velocity the first.
    Wherever a part program causes a significant change in cutter-path direction, such as in a transition from a straight line
    to curve, any axis acceleration that is required to maintain a constant cutter-path vector feedrate through that transition
    may cause vibration or shock to be induced into the machine structure.
    The Jerk Control function can be used to reduce shock and any resultant position error from sudden axis acceleration.
    Jerk Control temporarily modifies the cutter-path vector feedrate by applying a smoothing effect progressively modifying
    the rate-of-change of acceleration (Jerk).
    Without using Jerk Control, Bell-Shaped Acceleration alone would apply a harsher, constant rate-of-change, acceleration
    profile. The permissible rate-of-change of acceleration (Jerk) is set by CNC parameters for each machine axis; these
    limits are usually set in advance by the machine-tool-builder. Any velocity adjustments applied by the Jerk Control
    function are calculated as true positional commands
    and hence incur only minimal acceleration or deceleration delays
    (Acc/Dec Before Interpolation).
    This function is a basic function in FANUC Series 0i-MF Plus (Type 0, 1 and 3) and 0i-LF Plus.
    Benefits
    • Reduction of machining errors caused by shock and vibration induced into the machine structure that result of
    sudden changes in axis acceleration

    ----------

    Page 262 of their current 2020 feature catalogue (more specifically relating to jerk control COMBINED with G64 motions, but its all the same at the root. https://www.fanucamerica.com/docs/de...-catalogue.pdf

    Likewise siemens who outline the same method. And Delta. And LNC. And SGZH. And Heidenhain. And DDCS. And Centroid. And Beckhoff. In fact, I have yet to find a single control that states they do anything differently besides the hobby controls which do nothing at all.... Including Eding.

    Eding has no jerk control methodology, it makes no reference to anything other than constant acceleration in the manual. It is also a open loop pulse driven system with no communication with the drive - not even encoder feedback. "Make your servo settings sloppy and hope for the best" is not jerk control, it's NO control.



    You need to do way better in your trolling, this is getting old. I only reply to make sure people don't take your information as some sort advice, but by now they all get it, so I'm done.
    (There is a reason most of the forum has him on ignore,) I wonder what happened and why you are replying then, I guess the logarithm is broken (nuts)

    You should not talk about controls that you have never used or installed and have No hands-on experience with, it just shows your ignorance in your posts


    The Fanuc completely changed their whole control platform, and none of what you have been posting is current or reverent, your Google search is only as good as what you find without any knowledge or education in the subject, you can pretend to know, but it shows in your Google posts you have no clue on this subject, anyone can do a Google search and post what you have

    You seem fixated with G64 making it out to be more than what it is, in the real world nobody uses it. unless they have a very old machine this helps the Hobby user some, to smooth out the bumps in the road.

    Eding does have Look-ahead corner control and works very well, again your lack of of use and knowledge, shows your postings are incorrect.
    Mactec54

  2. #2
    Join Date
    Jan 2018
    Posts
    1516
    Quote Originally Posted by mactec54 View Post
    your Google search is only as good as what you find without any knowledge or education in the subject
    Can't stand google search sometimes.
    It's always making old cr*p look up to date.

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