PID autotuning - not working for heating application
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From: RRogers on 15 Nov 2009 18:05 On Nov 15, 8:17 am, pnachtwey <pnacht...(a)gmail.com> wrote: > On Nov 14, 1:25 pm, RRogers <rerog...(a)plaidheron.com> wrote: > > > clip.......... > > > > ... > > > > read more » > > > Okay I have uploaded the file that corresponds to step inputs. This > > one is fairly clean.http://www.plaidheron.com/ray/temp > > static-test.jpg > > static-test.xls > > Should get you there. If there is a permission problem let me know; I > > will resolve. > > > The .jpg is a graph to get the idea. T-11 is included to verify the > > environment didn't change much. > > The .xls is: sheet 1 graphs, sheet static-test is the long > > experimental run covering about 4 hours > > Cols: T-1,2,3 are the three direct thermistors used later for control > > Cols: M,N,O are the PWM drives, 0-100%, to the corresponding heaters; > > the trailing columns can be ignored > > The intermediate columns are various sensors distributed away from the > > actively controled points. > > > Let me know and I (or you ) can cross-verify your model against other > > experimental runs. > > > I have other experimental data sets that are less clear; some are > > basically random inputs to try to satisfy the sys-id programs. > > > Ray > > When starting the identification process the system must be at steady > state. The three temperature sensors are at different temperatures. > That could be steady state for a combination of heater outputs but it > is hard to know. If all the heaters started at the same ambient > temperature then I know the system was at steady state. > > Peter Nachtwey Peter, Okay, I will post that experiment but it's not as clean. Since I only had shared access to the prototype I couldn't let the machine cool down long enough for a real restart, and (of course) the room temperature changed. These thermal systems have really long "tails"; some sections (plastic) absorb heat and let it out very slowly. Ray
From: RRogers on 15 Nov 2009 19:43 On Nov 15, 8:17 am, pnachtwey <pnacht...(a)gmail.com> wrote: > On Nov 14, 1:25 pm, RRogers <rerog...(a)plaidheron.com> wrote: > > > clip.......... > > > > ... > > > > read more » > > > Okay I have uploaded the file that corresponds to step inputs. This > > one is fairly clean.http://www.plaidheron.com/ray/temp > > static-test.jpg > > static-test.xls > > Should get you there. If there is a permission problem let me know; I > > will resolve. > > > The .jpg is a graph to get the idea. T-11 is included to verify the > > environment didn't change much. > > The .xls is: sheet 1 graphs, sheet static-test is the long > > experimental run covering about 4 hours > > Cols: T-1,2,3 are the three direct thermistors used later for control > > Cols: M,N,O are the PWM drives, 0-100%, to the corresponding heaters; > > the trailing columns can be ignored > > The intermediate columns are various sensors distributed away from the > > actively controled points. > > > Let me know and I (or you ) can cross-verify your model against other > > experimental runs. > > > I have other experimental data sets that are less clear; some are > > basically random inputs to try to satisfy the sys-id programs. > > > Ray > > When starting the identification process the system must be at steady > state. The three temperature sensors are at different temperatures. > That could be steady state for a combination of heater outputs but it > is hard to know. If all the heaters started at the same ambient > temperature then I know the system was at steady state. > > Peter Nachtwey Peter, Okay, I will post that experiment but it's not as clean. Since I only had shared access to the prototype I couldn't let the machine cool down long enough for a real restart, and (of course) the room temperature changed. These thermal systems have really long "tails"; some sections (plastic) absorb heat and let it out very slowly. Ray
From: RRogers on 15 Nov 2009 19:54 > > When starting the identification process the system must be at steady > > state. The three temperature sensors are at different temperatures. > > That could be steady state for a combination of heater outputs but it > > is hard to know. If all the heaters started at the same ambient > > temperature then I know the system was at steady state. > > > Peter Nachtwey > > Peter, > Okay, I will post that experiment but it's not as clean. Since > I only had shared access to the prototype I couldn't let the machine > cool down long enough for a real restart, and (of course) the room > temperature changed. These thermal systems have really long "tails"; > some sections (plastic) absorb heat and let it out very slowly. > > Ray Well I looked around, while I do have SIMO heater by heater data the subject heater input is random trying to obtain information the sys-id routines like. Incidentally: In case I forget; some of the data was taken has a problem which I found out after much work and threatening to sue the programmers; the PWM percentages were rounded down to units not tenths and such. That's the reason for the second set of PWM data. Maybe I should have quit when they separated the programming from engineering (: Endeavour to write and check your own control and monitoring algorithms; you will have a happier life. Ray
From: RRogers on 15 Nov 2009 20:16 > > When starting the identification process the system must be at steady > > state. The three temperature sensors are at different temperatures. > > That could be steady state for a combination of heater outputs but it > > is hard to know. If all the heaters started at the same ambient > > temperature then I know the system was at steady state. > > > Peter Nachtwey > > Peter, > Okay, I will post that experiment but it's not as clean. Since > I only had shared access to the prototype I couldn't let the machine > cool down long enough for a real restart, and (of course) the room > temperature changed. These thermal systems have really long "tails"; > some sections (plastic) absorb heat and let it out very slowly. > > Ray Well I looked around, while I do have SIMO heater by heater data the subject heater input is random trying to obtain information the sys-id routines like. Incidentally: In case I forget; some of the data was taken has a problem which I found out after much work and threatening to sue the programmers; the PWM percentages were rounded down to units not tenths and such. That's the reason for the second set of PWM data. Maybe I should have quit when they separated the programming from engineering (: Endeavour to write and check your own control and monitoring algorithms; you will have a happier life. Ray
From: JCH on 16 Nov 2009 05:45
"RRogers" <rerogers(a)plaidheron.com> schrieb im Newsbeitrag news:b489cc63-2964-418f-9dcd-90fd9e4b3683(a)z3g2000prd.googlegroups.com... > On Nov 15, 6:14 am, "JCH" <ja...(a)nospam.arcornews.de> wrote: >> "RRogers" <rerog...(a)plaidheron.com> schrieb im >> Newsbeitragnews:3d4e61d7-69d7-4431-a12a-88e31d5868f7(a)x5g2000prf.googlegroups.com... >> >> >> >> > clip.......... >> >> ... >> >> >> read more � >> >> > Okay I have uploaded the file that corresponds to step inputs. This >> > one is fairly clean. >> >http://www.plaidheron.com/ray/temp >> > static-test.jpg >> > static-test.xls >> > Should get you there. If there is a permission problem let me know; I >> > will resolve. >> >> > The .jpg is a graph to get the idea. T-11 is included to verify the >> > environment didn't change much. >> > The .xls is: sheet 1 graphs, sheet static-test is the long >> > experimental run covering about 4 hours >> > Cols: T-1,2,3 are the three direct thermistors used later for control >> > Cols: M,N,O are the PWM drives, 0-100%, to the corresponding heaters; >> > the trailing columns can be ignored >> > The intermediate columns are various sensors distributed away from the >> > actively controled points. >> >> > Let me know and I (or you ) can cross-verify your model against other >> > experimental runs. >> >> > I have other experimental data sets that are less clear; some are >> > basically random inputs to try to satisfy the sys-id programs. >> >> Basically refering to >> >> *http://home.arcor.de/janch/janch/_control/20081123-real-system-model/ >> >> Can you approach the best possible ODE (process transfer function) in a >> range of order <= 6? >> >> C6 y'''''' + C5 y''''' + C4 y'''' + C3 y''' + C2 y'' + C1 y' + y = K >> >> Decimal commas! >> >> Example data points: 30 >> >> 0 0 >> 0,062 0 >> 0,124 0,002 >> 0,187 0,012 >> 0,249 0,04 >> 0,311 0,093 >> 0,373 0,17 >> 0,435 0,266 >> 0,498 0,373 >> 0,56 0,48 >> 0,622 0,581 >> 0,684 0,671 >> 0,746 0,748 >> 0,809 0,811 >> 0,871 0,861 >> 0,933 0,899 >> 0,995 0,929 >> 1,057 0,95 >> 1,12 0,966 >> 1,182 0,977 >> 1,244 0,984 >> 1,306 0,99 >> 1,368 0,993 >> 1,431 0,996 >> 1,493 0,998 >> 1,555 0,999 >> 1,617 1 >> 1,679 1 >> 1,741 1 >> 1,804 1,001 >> >> -- >> Regards JCH >> >> My solution see down here: >> >> Decimal commas! >> 1,048734E-06 y'''''' + 6,2427E-05 y''''' + 0,001548347 y'''' + 0,02048154 >> y''' + 0,1523982 y'' + 0,6047773 y' + y = 1,000953 > > We seem to have a disconnect here. > The system is MIMO which means that a finite model would have a set of > simultaneous differential equations... If you can't find one differential equation (process transfer function) as part of a set you won't be able to solve anything. See basics and decoupling of MIMO system: * http://home.arcor.de/janch/janch/_control/20091117-mimo-system/ -- Regards JCH |