Well I tried like Andy said increasing the ferror and I can work a lot better. Also my acceleration was too much so I decreased it and now I have a error of 0.2 mm without fine tunning and with the motor moving air for now, I guess that when it's attached to the screw this will be a lot better.
One thing about that error is that the motor keeps oscillating between those two points but never stops. Is this a normal behaviour on a bad tunned motor? If I tune it well I would expect the oscillation to dissapear or at least stop at some moment? Thanks as always! Leonardo. 2013/12/4 Leonardo Marsaglia <leonardomarsagli...@gmail.com> > Thanks Andy and Kirk. > > I think there's nothing activated on the VFD by now, the last whing was > the acceleration. > > About what you say andy, this VFD it's capable of handle a smooth turn > without load at 1 hz, but I don't know what's going to happen when the > motor is attached to the screw. > > I will try tomorrow with your advice of using more following error and try > to eliminate the oscilation. I thought it was tricky this way because > without the screw all the inertia has to be stopped without help. When it's > connected to the screw it will behave a lot different, I'll be ataching the > motor in the next days because I'm finishing the mechanical adaptation for > the encoder. > > > 2013/12/4 andy pugh <bodge...@gmail.com> > >> On 4 December 2013 22:19, Leonardo Marsaglia >> <leonardomarsagli...@gmail.com> wrote: >> >> > I managed to move the motor and do some tests but I can't get rid of the >> > oscillation from the PID. If I follow the classic way of tunning the >> > algorithm when I increment P I don't see any oscillation until I disturb >> > the motor. When that happens I get a really strong vibration and right >> > after that a following error. What I'm saying is I can't even start to >> test >> > my error to decrease it. >> >> Firstly I would set the folllowing error to about 16, two full turns. >> (if you get more than that, then you probably do want to stop). >> >> Then see if you can kill the oscillation with some D term. >> >> Tuning a bare motor is often hard even when it is a real servo, and an >> induction motor is likely to be worse. >> >> One problem you are likely to have, and which I had, was that my VFD >> didn't do anything at all unless the frequency demand was more than >> 5Hz. >> The solution to this might be some sort of inverse deadband, so that >> even a small velocity demand is at least 5Hz. (1V to the VFD or >> thereabouts) >> >> One way to do this, with a fair bit of tunability is with the >> "lincurve" HAL component. You could set that up to give no output with >> +/- 0.1V demand, 1V with >0.1V demand with X = -10, -0.1. -0.1, +0.1, >> +0.1 +10 and Y = -10, -1, 0, 0, 1, 10. >> >> >> -- >> atp >> If you can't fix it, you don't own it. >> http://www.ifixit.com/Manifesto >> >> >> ------------------------------------------------------------------------------ >> Sponsored by Intel(R) XDK >> Develop, test and display web and hybrid apps with a single code base. >> Download it for free now! >> >> http://pubads.g.doubleclick.net/gampad/clk?id=111408631&iu=/4140/ostg.clktrk >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > > > > -- > *Leonardo Marsaglia*. > -- *Leonardo Marsaglia*. ------------------------------------------------------------------------------ Sponsored by Intel(R) XDK Develop, test and display web and hybrid apps with a single code base. Download it for free now! http://pubads.g.doubleclick.net/gampad/clk?id=111408631&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
