Introduction: Hot Dental plate Automatic Control Organization (HPACS)

This jut out aims at providing a orbicular intuitive way of life of understanding how to do Automatic PID tuning using a smoke. What I have made is supported the Åström–Hägglund method for deriving parameters using have intercourse-smash insure to bring out system characteristics and subsequenctly chose parameters founded on this knowledge. There is nothing secret to it and info can be found hither: https://en.wikipedia.org/wiki/PID_controller#Loop... And for chosing parameters you can read a snatch present: https://nut.wikipedia.org/wiki/PID_controller#Loop...

To make it decent a Nextion 3.2" HMI interface is added for user input and displaying variant variables real-time. Simply I also made a Serial concluding version of the library which makes the externalise way cheaper !

The real background story is that partly I promised my pop to make a temperature control for melting bees wax, partly I wanted to refresh my basic control theory and finally I wanted to look into auto tuning of PID controllers. Unofficially I also managed to use it for Sous Vide making nice steaks and Bearnaise sauce A part of the testing !

WARNING!

I am working with 230 V here which is dangerous if you get along not eff what you are doing ! I am an electrician and electronics engineer so I rich person some experience here - but Doctor of Osteopathy NOT work with 230 V if you are non comfortable with it and take great care not to touch live wires ! Also, beware of the cut-rate SS-relays with regards to possible fire hazard as this has been seen by some people (not by me though).

Supplies

  • A cheap WASCO Hotplate (could be a better one - e.g. an Ikea induction plate)
  • A cheap SS-relay
  • A Dallas onewire temperature sensor
  • An Arduino Mega
  • (Optional) A Nextion 3.2" HMI port/display
  • 5V power supplying for the Arduino

Step 1: Assembly

I only built an enclosure for the HMI variation of the project since this is what I ended heavenward using. So, I successful an enclosure for accommodation relay, HMI and Arduino. I also made a clamp for the temperature detector just because I could...

Step 2: Coding

All the code for HMI and Arduino is available at my Git repo for the project.

I commented a good deal in the inscribe to try fashioning it easier to read and understand. But essentially I set dormie a actually larghetto PWM for the sulfurous-plate and a timer disturb for the state-motorcar/control and that is really information technology.

Then there is of course the tuning routine and the control itself + HMI or Ordering interface...

I do something that I'm non a giant fan of in that codification, and that is to use serial print in a timekeeper interrupt. Serial impress takes a lot of time and should real be avoided in a timer interrupt...

The tuning workings as follows:

  1. Set PWM duty cycle to 40%
  2. Await until setpoint temperature is reached
  3. Set PWM duty cycle to 0%
  4. Wait until temperature is infra setpoint
  5. Repeat pace 1-4 until e.g. 3 periods with almost same time and amplitude is seen
  6. Calculate paraemters for Pelvic inflammatory disease based on the above

Pretty simple ;)

Step 3: Testing !

Now that the coding is done its meter for testing. In the former section I showed the tuning graphically from a test - so for that in that location's not much left to say. But a couple of tests using the obtained parameters is shown here.

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