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Re: Torque mode troubles persist with Pixie board

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  • Keith Clark
    Thanks Mark, that is just what I needed something to look for. So far so good, no oscillation and crisp rapids and stops. Keith ... voltage ... rather than
    Message 1 of 45 , Feb 1, 2008
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      Thanks Mark, that is just what I needed something to look for. So far
      so good, no oscillation and crisp rapids and stops.

      Keith

      --- In mach1mach2cnc@yahoogroups.com, "Mark Vaughan" <mark@...> wrote:
      >
      > Hi Keith
      >
      > While speed mode is wrong, I suppose loosely you could say that the
      voltage
      > output from the pixie calls for some torque, or incorrectly speed, both
      > initially require a throttling effect, if the machine has enough inertia
      > then the pixie will correct for the fact that that it is speed
      rather than
      > torque, if the speed isn't enough, the differential term should add some
      > more.
      >
      > Mathematically it works within certain constraints.
      >
      >
      >
      > All you can do is try it for a while. Look at the pixie test traces,
      can you
      > get a nice step response, doesn't need big steps since machs
      acceleration
      > can restrict the maximum step error the system sees in practice,
      just a nice
      > small step say 50 to 100 with text book trace. If it won't totally
      come to
      > position, is the error, or small oscillation left acceptable, remember
      > though oscillation means more wear and tear on the machine.
      >
      > When you run the machine and set up machs acceleration and velocity
      listen
      > for oscillation, and when it gets to position watch to see if it is
      > fidgeting or gets there nice and smartish as it should with a crisp
      stop, as
      > you increase the acceleration and speed, some of these problems may
      arise,
      > on rapid moves you will see a little bounce / overshoot when it stops, a
      > certain amount is normal.
      >
      > When you are machining look for surface patterns on the work piece,
      this is
      > another sign of resonance, in all cases if a problem arises back off
      > acceleration or speed until it stops.
      >
      >
      >
      > If it all looks good, and since it's the only way we can get it
      going then
      > run it for a while and see how you go, a few limitations may well be
      more
      > acceptable than the cost of another drive.
      >
      > But to begin with stay with the machine and look for problems, the
      risk is
      > unstable oscillations that increase more and more until it breaks
      something.
      > This is the bit all control systems engineers fear, unlikely but
      possible.
      > If it starts to shack the hell out of itself and your building hit the
      > Estops and shut it down.
      >
      >
      >
      > best of luck.
      >
      >
      >
      > Regs Mark
      >
      >
      >
      > Dr. Mark Vaughan Ph'D., B.Eng. M0VAU
      >
      > Managing Director
      >
      > Vaughan Industries Ltd., reg in UK no 2561068
      >
      > Water Care Technology Ltd, reg in UK no 4129351
      >
      > Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH UK.
      >
      > Phone/Fax 44 (0) 1872 561288
      >
      > RSGB DRM111 (Cornwall)
      >
      > _____
      >
      > From: mach1mach2cnc@yahoogroups.com
      [mailto:mach1mach2cnc@yahoogroups.com]
      > On Behalf Of Keith Clark
      > Sent: 31 January 2008 23:01
      > To: mach1mach2cnc@yahoogroups.com
      > Subject: [mach1mach2cnc] Re: Torque mode troubles persist with Pixie
      board
      >
      >
      >
      > Mark,
      >
      > I wonder what you think about the motor running in speed reference
      > mode. I just can't get it to run in torque mode. If it runs
      > smoothly, accurately and quietly, I guess I can't complain. Is there
      > anything I should look for that would preclude me from just leaving
      > well enough alone? I just can't find any fault with how it is
      > working but I have not tried under load yet.
      >
      > Thanks,
      > Keith
      >
      > --- In mach1mach2cnc@ <mailto:mach1mach2cnc%40yahoogroups.com>
      > yahoogroups.com, "Keith Clark" <clarkfamily5@>
      > wrote:
      > >
      > > Mark,
      > >
      > > I think an error in the software makes the most sense but there are
      > > so many variables.
      > >
      > > Thanks,
      > > Keith
      > >
      > > --- In mach1mach2cnc@ <mailto:mach1mach2cnc%40yahoogroups.com>
      > yahoogroups.com, "Mark Vaughan" <mark@> wrote:
      > > >
      > > > Hi Keith
      > > >
      > > > Your understanding here is the same way I thought they worked, they
      > > are
      > > > variables I have never adjusted before on a pixie.
      > > >
      > > > Very strange, I'll have to have a think about this, or perhaps
      > > theres an
      > > > error in this part of the pixie like we know something is a little
      > > odd with
      > > > Ki.
      > > >
      > > >
      > > >
      > > > Regs Mark
      > > >
      > > >
      > > >
      > > > Dr. Mark Vaughan Ph'D., B.Eng. M0VAU
      > > >
      > > > Managing Director
      > > >
      > > > Vaughan Industries Ltd., reg in UK no 2561068
      > > >
      > > > Water Care Technology Ltd, reg in UK no 4129351
      > > >
      > > > Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH UK.
      > > >
      > > > Phone/Fax 44 (0) 1872 561288
      > > >
      > > > RSGB DRM111 (Cornwall)
      > > >
      > > > _____
      > > >
      > > > From: mach1mach2cnc@ <mailto:mach1mach2cnc%40yahoogroups.com>
      > yahoogroups.com
      > > [mailto:mach1mach2cnc@ <mailto:mach1mach2cnc%40yahoogroups.com>
      > yahoogroups.com]
      > > > On Behalf Of Keith Clark
      > > > Sent: 29 January 2008 04:03
      > > > To: mach1mach2cnc@ <mailto:mach1mach2cnc%40yahoogroups.com>
      > yahoogroups.com
      > > > Subject: [mach1mach2cnc] Re: Torque mode troubles persist with
      > > Pixie board
      > > >
      > > >
      > > >
      > > > Mark,
      > > >
      > > > I tried to turn down the parameter 11? ( the maximum output ) on the
      > > > Pixie and it did not do anything that I could notice. If the goal
      > > was
      > > > to limit the output to 3 volts would I cut down parameter 11 by 3/5
      > > ths?
      > > >
      > > > Also, when I raised the parameter 13 from 1 to 2, the motor
      > > oscillated
      > > > radically. The manual says this should prevent oscillation.
      > > >
      > > > It's not making much sense at this point.
      > > >
      > > > Thanks,
      > > > Keith
      > > >
      > > >
      > > >
      > > >
      > > >
      > > > [Non-text portions of this message have been removed]
      > > >
      > >
      >
      >
      >
      >
      >
      > [Non-text portions of this message have been removed]
      >
    • Mark Vaughan
      Could be still a rotor encoder as well. Some AC servo controls have the rotor encoder calibrated to exact position on the motor, they are hell to setup again
      Message 45 of 45 , Feb 5, 2008
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        Could be still a rotor encoder as well.

        Some AC servo controls have the rotor encoder calibrated to exact position
        on the motor, they are hell to setup again if you strip them down.

        Most however now start to turn the motor and are quickly able to detect the
        rotor encoder alignment which they then remember and resync as needed.

        If that signal is down they just generate a slow three phase output while
        looking for the signal which is what you are getting.



        Regs Mark



        Dr. Mark Vaughan Ph'D., B.Eng. M0VAU

        Managing Director

        Vaughan Industries Ltd., reg in UK no 2561068

        Water Care Technology Ltd, reg in UK no 4129351

        Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH UK.

        Phone/Fax 44 (0) 1872 561288

        RSGB DRM111 (Cornwall)

        _____

        From: mach1mach2cnc@yahoogroups.com [mailto:mach1mach2cnc@yahoogroups.com]
        On Behalf Of Keith Clark
        Sent: 04 February 2008 22:11
        To: mach1mach2cnc@yahoogroups.com
        Subject: [mach1mach2cnc] Re: Torque mode troubles persist with Pixie board



        Dave,

        Fixed - found a loose wire at the encoder inputs! Problem is now the
        Yaskawa amp for the small motor is not working. The jog function does
        not work and the motor continually turns when it should be still. I
        am waiting for the repairman to come visit. I may have to scrap the
        small motor and switch to a stepper unless I can get the board
        repaired. I am hoping there is some adjustment but not to optimistic.

        Thanks
        Keith

        --- In mach1mach2cnc@ <mailto:mach1mach2cnc%40yahoogroups.com>
        yahoogroups.com, "Mark Vaughan" <mark@...> wrote:
        >
        > That sounds as though you have a bad encoder wiring for the yaskawa
        drive.
        >





        [Non-text portions of this message have been removed]
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