I would agree that antiwindup is important when you have integrators. They always seem to cause trouble without it, in applications as diverse as car throttle control and time-domain filtering of respiratory data. I would also recommend, sometimes, the use of feed-forward control to provide an estimate of power demand without relying on the integrator : although most useful for speeding the response, it can also reduce the expected integrator term and hence allow more aggressive antiwindup.
On Sat, Jul 6, 2019 at 9:00 AM Glen English VK1XX < glenl...@pacificmedia.com.au> wrote: > Hi Rick > > Thank you very much for the reply and the suggested leads. I think your > work on the balanced bridge oscillator was both preeminant and seminal . > > I have read all the papers on it, and there are few other things in my > 30 years of this field professionally that really impress me as much in > the new approaches and new thinking on the entire unit. Agreed on the > PII^2D control system. > > I've built a few OCXOs back in the 90s, the best I did on (inner) oven > control was using dual glass bead thermistors in a bridge configuration > with lots of gain driving a simple opamp integrator. The opamp was > chopper stabilized and I ensured the op amp never operated in the > crossover region of the opamp output driver. These were on AT cuts at > 97 deg C ... > > cheers > > Glen. AI6UM / VK1XX > > > > On 6/07/2019 2:37 PM, Richard (Rick) Karlquist wrote: > > On 7/5/2019 8:20 PM, Glen English VK1XX wrote: > >> Has anyone got this , is the PIC read data prohibited ? > >> > >> Is it still a closely guarded secret?, there were some very clever > >> and novel ideas used in that slab, in my opinion. > >> > >> Glen > >> > > > > Hi Glen. I worked on this project, but am an RF/Analog > > guy. The product line was sold to Symmetricom 20 years > > ago and they didn't continue the E1938A. At that point, > > there were no closely guarded secrets. I don't know what > > happened to the source code. The last contract manufacturer > > for the E1938A was Scotts Valley Magnetics. You could > > contact them and see if they have the PIC info. In theory, > > they would have had to have it to program the PIC's. > > > > The most clever thing in the PIC (AFAIK) is the oven > > controller with the double integrator. "P, I, I^2, D". > > Len Cutler was the mastermind behind this. I believe > > he leveraged his experience with double integrators used > > in Cs control loops. I remember him telling me that the > > secret was to have an "anti-windup" algorithm. Whatever > > he did, the results were phenomenal. I spent countless > > days in the lab exercising the loop and it always worked > > perfectly. > > > > Rick Karlquist, N6RK > > > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.