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  • Dimal
    replied
    Re: PID Silvia Sydney

    Originally posted by bloop link=1143536728/75#77 date=1145885925
    Ive tried altering 1-7 but its still quite random.
    Hi Bloop,

    Playing around with the Overshoot function is not very useful really, until youve managed to fine tune the PID settings to their optimum for your particular requirements. Once you have achieved that, the Overshoot function will prove to be more effective,

    Cheers,
    Mal.

    Leave a comment:


  • bloop
    replied
    Re: PID Silvia Sydney

    Hi Christian,

    Good to hear you have the same setup with a Silvia. My experiences with the overshoot are exactly the same as yours.

    I havent had a play with it lately, its too frustrating for me!!!

    Autotune also came up with roughly the same figures.

    Ive tried altering 1-7 but its still quite random.

    I rarely pull consecutive shots unless theres guests over so it doesnt bother me so much, but still Id like to improve on it. Ill have a play tomorrow and let you know the outcome.

    Leave a comment:


  • Dimal
    replied
    Re: PID Silvia Sydney

    Good news Christian ,

    Those new parameters look a lot more healthy than before, so thats a good start. Yes, the AutoTune feature doesnt affect anything other than the PID parameters, all other functions have to be adjusted manually.

    The best way to approach tuning your current settings now, to achieve less overshoot, is use the guide from the link I provided earlier as you mention, and once you have it operating as tight as you can get it from this perspective, then you can start upping the Function at Line 1-7. The only detriment that increasing this Function causes, is to delay the arrival at Setpoint from cold by a small margin, the higher the value of this parameter. Its no big deal though, just a matter of tweaking it so that the all round performance of the controller is to your satisfaction.

    All the best,
    Mal.

    Leave a comment:


  • christians
    replied
    Re: PID Silvia Sydney

    Hi there Mal,

    Thanks for the link, has proven very useful.

    I started again with the auto tune process, and this time its proven to be alot more stable. I think my problem before was starting the auto-tune feature before the temperature was reasonably stable, therefore skewing the settings.

    Parameters as follows:-

    p = 4.7
    i = 187
    d = 46
    tv = .40 ( target value, this is the default btw, auto tune doesnt appear to modify this parameter )

    With the new settings, while idle the setpoint is kept almost perfectly, every 30 seconds or so it might drop 0.1C but only for a brief moment. Recovery times after a shot will need a fair amount of tweeking though, as I observed the following (approximate times) :-

    * initial overshoot of +0.5C (1 minute)
    * slow decrease to +0.3C (1 minute)
    * slow increase to +2.3C (4 minutes)
    * this is where things leveled out (1 minute)
    * slow decrease to setpoint (5 minutes)


    Overall recovery of over 12 minutes. Which is actually fine for my usage, but Id like to rain that in to around 3 minutes if possible. Next step is to follow the guidelines in your link, onto round three


    christian

    Leave a comment:


  • Dimal
    replied
    Re: PID Silvia Sydney

    Hi ChristianS,

    Good to see you having a go CS [smiley=thumbsup.gif]. To try and cut down on the Over/Under-shoot, you will need to dial-in some Integral. The most important factor though as Sparky has mentioned before, is to get the Proportional Band parameter fairly close to ideal before you start introducing the other parameters. Once this Steady State error has been identified, it is a much simpler process to then target the Integral and Derivative.

    I realise the Silvia has a slightly different Boiler design to the Mokita but the final PID parameters shouldnt be streets away from the settings Ive arrived at and Im surprised that your Proportional Band is set at 1.0, seems very low to me. For example, the P on my Mokita is set at 3.8. Your Derivative setting of 40 by contrast seems a bit too high, the Mokitas is set to 16 and the Integral is set to 155. Function Item Line 1-7 is set to 0.85.

    Just out of interest, where does the Autotune routine leave your PID settings? These numbers should at least be in the ballpark and give somewhere to start. I highly recommend you browse this link https://<span style="color:#ffcc00">...m/qmbst</span> to PID Tuning to help you arrive at specific settings to suit the Silvia. Hope some of this is helpful,

    Cheers,
    Mal.

    Leave a comment:


  • christians
    replied
    Re: PID Silvia Sydney

    Hey there Bloop and everyone else interested,

    After following this thread for a while I finally bit the bullet and PIDed the silvia last friday evening. Im using the same SR1 PID module, and 40A SSR.

    I started out by having the T/C attached on the opposite side to the water inlet valve (next to brew T/S). Auto tuning performance was good but not great, large overshoot after a shot, settling down after say 5 minutes to +/- 2C). Instead of manually tuning I decided to try Mals idea of having the T/C attached right next to the water inlet. I can live with the compromised steam T/S since I never use it anyway.

    Ok so all back together and I attempt auto tuning. Massive overshoot, massive recovery times Quite obvious that this setup needs manual tuning. After reading a few online tutorials I opted for a "Tune By Feel" approach, first starting out with all other parameters except P turned off, adjusting until just before temperature oscillation then adding the D parameter. All the while oberving how the different parameters and their values effect things.

    Anyway Im going to begin the whole process again starting out with just P, while documenting the effects. But in the meantime here are my current parameters, which sort of work ok...

    P: 1.0
    I: off
    D: 40
    Target Value (1-7): 1

    With these parameters when silvia has been pre-heated for around 30 minutes :-

    +0.6C and -0.4C, fairly regular cycle, say 30 seconds.

    After a double shot, overshoot is around +3.6C, with a recovery time of &lt; 4 minutes.



    Happy PIDing everyone ;D

    christian

    Leave a comment:


  • Dimal
    replied
    Re: PID Silvia Sydney

    Originally posted by Billi link=1143536728/60#68 date=1145321228
    Hi Bloop,
    I have followed your journey with great interest, because I have been thinking of taking the plunge myself. If it’s not too early can you let us know if the exercise has improved the shots you are pulling? Put another way, I’m sure that the P.I.D. will reduce the amount of time, temp. surfing, but I’m not convinced that it will do anything to improve the coffee.
    Thanks
    Bruce
    Gday Billi,

    Just my $0.02 worth....

    A properly set up PID Controller that is calibrated to produce Optimum Brew Water temperature to the top of the coffee cake each and every time, means that you can divert the attention required from you to control this aspect of espresso brewing to other criteria that may benefit from increased scrutiny. Ultimately this leads to the capability of being able to brew better quality coffee on a much more consistent basis, and I guess that is what we are all trying to achieve in the end ;D.

    Since installing and setting up the PID controller on my Mokita (more than a year now), I have noticed a considerable increase in the quality and consistency of my shots. As intimated above though, it cant all be attributed to the addition of the controller but being able to concentrate on other aspects of the process that accumulates and equates to better quality shots. Basically, Im one very happy PID camper ,

    Cheers,
    Mal.

    Leave a comment:


  • bloop
    replied
    Re: PID Silvia Sydney

    Billi, with good surfing technique, Im sure you can pull the same quality shots as a machine with a PID, however for me it was the convenience factor. To be honest I cant taste the difference between the shots I pull now and the shots I pulled in the past that were good. Its just Im pulling better shots on a more consistent basis now.

    JGG, I wouldnt call my enclosure attractive, especially after seeing yours!

    Mal, have you adjusted any other parameters besides 1-7 and the P/I/D values?

    Leave a comment:


  • Dimal
    replied
    Re: PID Silvia Sydney

    Originally posted by bloop link=1143536728/60#67 date=1145283477
    Thanks for the link and tips Mal. I tried adjust setting 1-7. It has made a big difference, the temperature is pretty much stable after about 2-3 minutes, but on occasion it still overshoots, it doesnt always give the same response each time. Is this normal?
    Hiya Bloop,

    Glad to hear that 1-7 has helped you out . Re. the occasional inconsistency in response.....
    This is significantly affected by the rate of pour for each shot, even slight differences in pour rate will produce a slightly different outcome.... thats where Fuzzy Logic assistance can be a big help, providing the FL code has been well written, Ive seen some pretty awful ones .

    I guess as you get more used to your improved performance Silvia, you will start to become more consistent with controlling each shot and the inconsistency in response will gradually diminish. One really important advantage in being able to control your shot temperature to the nth degree, is to ensure that the Brew Water Temperature is spot-on each and every time. With all else being equal, this has the flow-on effect of increased efficiency of coffee extraction from the grounds which improves flavour significantly, better and more crema and in turn produces much firmer, dryer pucks to boot (helps to make for quick turn-around for multiple shot sequences) 8-).

    All the best mate,
    Mal.

    Leave a comment:


  • jggall01
    replied
    Re: PID Silvia Sydney

    Bloop - I was not as fortunate as you in finding an attractive stock enclosure. I suffered with a poorly fitting Radio Shack project box on our Silvia for awhile, and then started making enclosures for others out of stainless steel in my home shop. When you started your project I had only made them for 1/32 DIN controllers, or I would have offered you one. The one I posted here is my first attempt at 1/16 DIN.

    -- JGG

    Leave a comment:


  • Billi
    replied
    Re: PID Silvia Sydney

    Hi Bloop,
    I have followed your journey with great interest, because I have been thinking of taking the plunge myself. If it’s not too early can you let us know if the exercise has improved the shots you are pulling? Put another way, I’m sure that the P.I.D. will reduce the amount of time, temp. surfing, but I’m not convinced that it will do anything to improve the coffee.
    Thanks
    Bruce

    Leave a comment:


  • bloop
    replied
    Re: PID Silvia Sydney

    JGG, that is one lovely enclosure you have there for the PID, is it custom made?

    Thanks for the link and tips Mal. I tried adjust setting 1-7. It has made a big difference, the temperature is pretty much stable after about 2-3 minutes, but on occasion it still overshoots, it doesnt always give the same response each time. Is this normal?

    Leave a comment:


  • Dimal
    replied
    Re: PID Silvia Sydney

    Great Job Bloop [smiley=thumbsup.gif],

    And a terrific commentary to boot [smiley=tekst-toppie.gif]. From looking at your photos, you have completed the work to a very professional level, if you dont mind my saying . I hope Sparky and Robusto have answered your queries ok and that you are now well on your way. As Sparky mentioned earlier, there are some great reference sites to be found by googling "PID Tuning Guide".

    I dont know if I provided this link to you before.....http://tinyurl.com/qmbst, but it is a particularly useful guide without too much techno-jargon and should help you optimise the controller to suit your way of doing things. Regarding the Shimaden controller.... it has a particularly useful feature that helps minimise over/under-shoot and can be found in the users brochure under line number "1-7.. Target Value Function Setting". The default value is set to a conservative value of 0.4.... Ive found that for the Mokita a setting of 0.85 does what I require so you might like to start there and try settings lower or slightly higher until the over-shoot settles back to the Setpoint by the time youre ready to pull another shot.

    Hope this helps a bit and as I said before, a really terrific job Bloop 8-),

    Cheers,
    Mal.

    Leave a comment:


  • Dimal
    replied
    Re: PID Silvia Sydney

    Originally posted by robusto link=1143536728/30#41 date=1144780216
    Appreciate what you are saying Mal, and I know Sparky disagrees with this, and I dont yet have a PID.

    But there have been numerous experiments done by Greg Scace and others at Google alt.coffee similar to yours, using a Silvia without a PID---and the result is a remarkable one or two degree variation during the pour, thanks to Silvias thermal stability.

    Robusto
    Hi Robusto,

    Sorry for taking a bit long to get back to you.... have been on holidays ;D.

    Actually, Im not really arguing about the Silvias built-in Thermal Stability, thats a well known fact and just as well documented.... have also read the Greg Scace notes on this too . What I was intending to point out but seemed to have failed, is that you can "cheat" a little bit when installing a PID by locating the Feedback t/c on the Boiler but close to the Cold Water Inlet. Once you have established the temperature gradient for the location of the t/c to the Top of Puck temperature, it is possible to shorten up the reaction time of the controller when pulling shots.

    As Sparky has pointed out, the time lag between actual temperature change and measured temperature change dictates to a large extent how a PID controller will perform in any particular application. By positioning the t/c bead nearer to the cold water inlet, it is possible to cheat a little because the t/c will detect a temperature drop before the temperature actually drops at the Group Brew Water Inlet. This equates into the controller reacting more quickly to pulling shots and thereby reheating the Boiler to optimum temperature ready for the next shot a little more quickly than if the t/c was located, e.g. close to the Group Brew Water Inlet. If the t/c was located here, there would be a more significant lag to take into account if optimising for quick recovery between shots was one of the criteria one used for installing a PID controller in the first place, as it was for me . If the capability is there, why not use it..... a bit of "feed forward" control doesnt hurt, even if one is cheating a little bit to implement it .

    Cheers,
    Mal.

    P.S.
    On my Mokita, the overshoot has been adjusted to be within the time frame for pulling consecutive shots, of about 3 minutes maximum. The maximum overshoot temp is no more than 1.5 degrees and by the time 3 minutes have elapsed, it is within +0.3deg C of the Setpoint. Unfortunately, it wouldnt be helpful for me to provide my PID parameters here, except where someone else is going to PID a Mokita Junior II the same as mine, as a Silvia has sufficient differences in key areas that will affect the optimum PID settings.

    Leave a comment:


  • jggall01
    replied
    Re: PID Silvia Sydney

    Bloop, you inspired me! I really liked your dual display setup and decided to re-PID my wifes Silvia this weekend. I removed the Fuji DIN 1/32 controller that had been there, and replaced it with the one you see. Attached is a little different variation on the PID theme.

    -- JGG


    Leave a comment:

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