On Tuesday 22 May 2018 18:58:52 Chris Albertson wrote: > Try this one, sorry it moved. > > http://www.cds.caltech.edu/~murray/books/AM08/pdf/am08-complete_22Feb0 >9.pdf > > -- Chris
That worked. Pretty well covers feedback systems from a cursory read, less technical but still complete. It looks like I ought to add it to my dead tree library, after I put some fresh ink in my big Brother, its got two nearly empty tanks ATM. And pick up another ream of good paper and a 2" D ring binder. Thanks Chris. > On Tue, May 22, 2018 at 3:04 PM, Gene Heskett <[email protected]> wrote: > > On Tuesday 22 May 2018 12:10:47 Chris Albertson wrote: > >> I just got a copy of "Feedback Systems - An Introduction for > >> Scientists and Engineers, Karl Johan °Aström and Richard M. Murray" > >> > >> The book is FREE and pdf format at > >> http://www.cds.caltech.edu/∼murray/amwiki > > > > I, like others are reporting Chris, am getting a not found error, > > and I suspect its the character in the little box in front of the > > "murray" string above. Its reproduced as a small "1/4" symbol here > > in the browsers (palemoon) font, and I don't think it belongs in a > > url address. Swag: caltecs way of establishing copyright? > > > >> It is an actual set book that seem to be exactly what anyone > >> working in this field needs to know. I'd say it is not is > >> mathematically oriented as a real university control theory book > >> and certainly well above the hobby level. It assume some know age > >> of Calculus but not a lot. Pretty much what the title says. But > >> it covers feedback, not just motion control. so things like op-amps > >> are covered. But you need to know that to if designing control > >> circuits > >> > >> I'm using stepper motors but already have DRO scales. It seems > >> that I should be able to combine open loop counting with closed > >> loop linear sensors. > >> > >> Suggestion above were good, thanks, because they contain a solution > >> I had not thought of, drive "I" with different data than "PD" > >> > >> On Tue, May 22, 2018 at 6:44 AM, John Kasunich > >> <[email protected]> > > > > wrote: > >> > On Fri, May 11, 2018, at 11:16 PM, Chris Albertson wrote: > >> >> I looked at the unit. It seems like a good idea. It uses > >> >> inputs from both the motor's shaft encoders and another encoder > >> >> on the object that is being moved, like a linear encoder on the > >> >> table. > >> >> > >> >> Question: Let's say I wanted to do this myself. Is there a > >> >> method that "everyone" in the machine tool industry uses for > >> >> combining the reading of multiple encoders? If not it seems > >> >> like the perfect application for a Kalman filter. > >> >> > >> >> But maybe you don't combine them but use the linear DRO for > >> >> position loop and the motor shaft encoders for velocity. > >> >> > >> >> This is a common problem I think with robot arms. The joint has > >> >> an angle sensor but the motor has a shaft encoder. So the > >> >> control loops might be nested. > >> >> > >> >> It reminds my the old saying the "A man with a watch knows what > >> >> time it is, a man with two watches is never sure of the time." > >> > > >> > We did something like this several years ago at Stuart's shop in > >> > Wichita, on a big Giddings and Lewis boring mill. > >> > > >> > We used two PID loops, with their outputs summed. The position > >> > command went to both loops. The feedback for one loop came from > >> > the motor encoder, and the feedback for the other loop came from > >> > the linear scale. > >> > > >> > The motor loop was tuned as normal, except that the I-gain was > >> > kept at zero. The linear scale loop was tuned using ONLY I-gain. > >> > So the linear scale loop corrected the fairly small steady-state > >> > errors due to things like the lead screw heating up (10 foot long > >> > screw, it adds up). It also compensates for backlash in the > >> > screw, and if there is much of that it leads to disturbances on > >> > direction reversal. Isn't going to fix a clapped out machine, > >> > but can improve the accuracy of a tight machine. > >> > > >> > > >> > -- > >> > John Kasunich > >> > [email protected] > >> > > >> > ----------------------------------------------------------------- > >> >--- ---------- Check out the vibrant tech community on one of the > >> > world's most engaging tech sites, Slashdot.org! > >> > http://sdm.link/slashdot > >> > _______________________________________________ > >> > Emc-users mailing list > >> > [email protected] > >> > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > -- > > Cheers, Gene Heskett > > -- > > "There are four boxes to be used in defense of liberty: > > soap, ballot, jury, and ammo. Please use in that order." > > -Ed Howdershelt (Author) > > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > > -------------------------------------------------------------------- > >---------- Check out the vibrant tech community on one of the world's > > most engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users -- Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
