arduino induction cooker96 Star 296 Fork 121 Manuel83/craftbeerpi Code Issues 89 Pull requests 10 Projects 0 Wiki Insights Autotune PID Stefan Hirschmann edited this page on May 2 · 13 revisions Pages 29 What is CraftBeerPI? Hardware Installation GPIO Relay Setup PiFace Setup Gembird Setup Thermometer Setup Buzzer Setup Hendi Induction cooker model 3500 M Setup do Setup Again Display support Software Installation First Installation Software Update IOS APP Using CraftBeerPI Quick Start Dashboard Kettle Autotune PID PWM control Experimental Manual PID adjustment Steps iSpindel Additional Hardware Import Recipes from Kleiner Brauhefer Remote interface of CBP Release Notes Trouble Shooting Clone this wiki locally https://github.com/Manuel83/craftbeerpi.wiki.git Clone in Desktop You can autotune your system following these steps: Set the folder permission of /home/pi/craftbeerpi to 777 (chmod) (this is to allow a file to be written later) In the kettle setup, select PIDAutotuneLogic as automatic logic Set a temperature setpoint. Usually something between 50°C to 60°C works well. Add the amount of water you usually use If you use a pump, turn it on Enable automatic control (the car symbol) Wait until the autotune-logic disables automatic control itself This can take up to an hour or more (depending on the individual hardware setup and the setpoint temperature), because the autotune logic tries to oscillate around the setpoint. The problem is, that after overshooting the setpoint, the autotune-logic waits until the temperature drops below the setpoint which usually takes some time. During tuning, you can read the autotune log by reading the craftbeerpi logfile and filtering for PIDAutotune: tail -f craftbeerpi/log/name_of_the_logfile | grep PIDAutotune After the autotune-process is completed successfully, the results will be saved to a file named pidparams.txt in the craftbeerpi working directory (usually: craftbeerpi/pidparams.txt). The autotune-process can fail. In this case, the automatic mode will be disabled, but no pidparams.txt file will be created. If autotune runs forever, the problem is usually either the heater being not powerful enough to reach the setpoint or the temperature not dropping below the setpoint fast enough for whatever reason (isolation, ambient temp. etc.). :bulb: Hint: If you aren't sure how auto tuning works, you can do a dry run on this brewing kettle simulation. PIDAutotune settings output step %: defines the the output of the autotune-algorithm when stepping up/down, e.g. output step = 100; step up (=heating) output = 100; step down (= cooling) output = -100. This setting should stay at 100% lookback seconds: determines how far the algorithm will look back when trying to find local (temperature) extrema (minima/maxima). If the algorithm recognizes even short peaks as extrema, you should increase this value. If it doesn't recognize actual extrema, you should decrease it. Usually the default of 30 seconds work fine. max. output %: limits the maximum power output. This is useful if your heater is overpowered and would heat up the kettle way too fast. If you don't want to limit your heater, leave this at the default value of 100% Tuning rules The PID-tuning rules basically are different ways of calculating the PID-parameters, which changes the behavior of the PID-controller (e.g. ziegler-nichols produces quite a lot of overshoot - not that good for brewing). See Ziegler–Nichols method. In most cases, brewing is the best rule for brewing, obviously ;) Example of pidparams.txt file: rule: ziegler-nichols P: 7.237315918538419 I: 0.32527262555228853 D: 40.25756979686996 rule: tyreus-luyben P: 5.592471391597869 I: 0.05655308148806835 D: 39.50237728985797 rule: ciancone-marlin P: 3.728314261065246 I: 0.3686423089592603 D: 20.482714150296722 rule: pessen-integral P: 8.788169329653794 I: 0.49371737807043786 D: 58.80805040144268 rule: some-overshoot P: 4.101145687171771 I: 0.18432115447963016 D: 60.83366102638127 rule: no-overshoot P: 2.4606874123030624 I: 0.11059269268777809 D: 36.50019661582876 rule: brewing P: 98.4274964921225 I: 0.6635561561266685 D: 230.52755757365532