On Sat, 20 Oct 2018 06:38:20 -0400 Gene Heskett <[email protected]> wrote:
> On Saturday 20 October 2018 01:12:02 Nicklas Karlsson wrote: > > > > > On 10/19/2018 2:12 PM, Nicklas Karlsson wrote: > > > > > Probably not, I have done quite a lot of search on Internet, > > > > > have a few books and have taken two courses specifically in the > > > > > area but if you have readily available I could always take a > > > > > look. > > > > > > > > > > I find a lot of documents about PID controllers and theory using > > > > > bode, nyquist diagrams. > > > > > > > > > > I found state space feedback and bode, nyquist diagram are > > > > > useful also for state feedback but then state space model is > > > > > available I prefer method to calculate gains using the model. I > > > > > could do state space feedback including integral action but get > > > > > the feeling a chapter or so is missing, maybe I have to write it > > > > > myself. > > > > > > Someone who really understands it needs to.. Whats out there tends > > > to talk more theory than hardware. ... > > > > The hardware need to be properly modeled. There are plenty of > > litterature available including for freely accesible on internet about > > electric motors. Static friction may be a problem but I think a > > properly lubricated machine have rather viscous friction which easy to > > put in a mathematical model suitable for control of machine. > > The std milling machine is a bigger problem WRG static friction than it > first appears, particularly the X motions. because the table is so long, > there's a huge disparity between the friction of the ways when the table > is centered vs when its at the end of its range. Static friction is a problem since it is non linear and will most probably cause problem then changing direction. If force is known for different speeds/directions feed forward should be able to compensate and integrator may eventually integrate it but with slower response. Viscous friction varies linearly with speed, a constant multiplied by speed and will add dampening to system. I think a well lubricated machine will have viscous friction since shear friction force in oil film vary linearly with speed. It is possible to use position dependent friction coefficient and I would guess linear interpolation would work well. I have to digest the inductance matrix for three phase machines then I will probably have a rather good understanding of the most common electric motors: induction, PMSM, BLDC, synchronous reluctance and DC. Do anybody happen to know how to identify the constants in a linear state space model? Regards, Nicklas Karlsson _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
