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  1. #201
    Join Date
    Jul 2018
    Posts
    6248

    Re: Jerk Control in machines

    Hi Jack - Here's a couple of papers. Shapers are not a compete solution. They "solve" the mechanical vibration side of things in a simple way, they do not improve jerk, they are like a noise cancelling circuit. You have to identify the potential vibrations of the machine and address those with the cancelling circuit. It does not change the trajectory to improve jerk.

    Once machines have accelerometers on the spindles (such as printers do) we can feed back the head accels and use jerk algorithms hand in hand with the shaper to solve it even better. Sophisticated machines have been doing this for some time. Peter

    https://www.mdpi.com/1424-8220/22/6/2186

  2. #202
    Join Date
    Jun 2015
    Posts
    4131

    Re: Jerk Control in machines

    their trajectory planner (it's open source, you can check it out) has no realtime requirements ... trajectory can be computed entirely offline
    a cnc system that does not adapt to inertia caused by part's mass change, can be considered to be "offline", or runing in only one dynamic mode; have the algorithms for such, and you can estimate toolpaths at a pc, with pretty acurrate time, without miscelanous like tool changes, magazines, etc

    I fear they are not up to the task for a machine tool where cutting loads are constantly changing
    basically, that's what a diff control is

    Once machines have accelerometers on the spindles ... Sophisticated machines have been doing this for some time
    another trick is the diff map, for controlers that are to operate at minimal cutting loads, like a high speed finishing, or a cam lathe, so to identify hot position, where motion is a bit out of control



    and in last 2 months, i did such applications :
    ... lathe sinusoisal acceleration rpm, for heavy parts, as basic acceleration is way to agressive
    ... harmonic control for live tools, like to destabilize the rpm, instead of using an endmill with variable flutes / kindly
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

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