PID-controller/brewing kettle simulation

This project has been created to support tuning a PID controller for a home brewing setup using CraftBeerPI.
It consists of a brewing kettle simulation, a PID controller (based on Arduino PID Library) and a PID autotune algorithm (based on Arduino PID Autotune Library)

Project goals

• allow users to find PID parameters which provide a sufficient basis for further manual tuning
• allow users to compare different PID parameters
• help users to understand how different PID parameters (Kp, Ki, Kd) influence a PID controller’s behavior (not only limited to home brewing setups)
• speed up auto tuning

PID comparison

Compare different PID parameters using the default kettle setup:
sim.py --pid 'reference' 98 0.66 230 --pid 'Kp too low' 30 0.66 230 --pid 'Ki too low' 98 0.01 230

PID autotune simulation

Simulate a PID autotune run on a 50l kettle with a 4 kW heater:
sim.py --atune --volume 50 --power 4

Generated PID parameters using different tuning rules:

rule: ziegler-nichols
Kp: 7.66141138481997
Ki: 0.4086086071903984
Kd: 35.91286586634361
rule: tyreus-luyben
Kp: 5.920181524633613
Ki: 0.07104217829560336
Kd: 35.239175741866745
rule: ciancone-marlin
Kp: 3.9467876830890756
Ki: 0.46308975481578485
Kd: 18.272165199486462
rule: pessen-integral
Kp: 9.30314239585282
Ki: 0.6202094930568547
Kd: 52.46132929992192
rule: some-overshoot
Kp: 4.341466451397983
Ki: 0.2315448774078924
Kd: 54.26833064247478
rule: no-overshoot
Kp: 2.60487987083879
Ki: 0.13892692644473545
Kd: 32.56099838548487
rule: brewing
Kp: 104.1951948335516
Ki: 0.8335615586684127
Kd: 205.64841085569392

Options

usage: sim.py [-h] [-p name kp ki kd] [-a] [-v] [-e] [-n] [-t T] [-s T]
              [--ambient T] [-i t] [-d t] [--sampletime t] [--volume V]
              [--diameter d] [--power P] [--heatloss x] [--minout x]
              [--maxout x]
optional arguments:
  -h, --help            show this help message and exit
  -p name kp ki kd, --pid name kp ki kd
                        simulate a PID controller
  -a, --atune           simulate autotune
  -v, --verbose         be verbose
  -e, --export          export data to a .csv file
  -n, --noplot          do not plot the results
  -t T, --temp T        initial kettle temperature in °C (default: 40)
  -s T, --setpoint T    target temperature in °C (default: 45)
  --ambient T           ambient temperature in °C (default: 20)
  -i t, --interval t    simulated interval in minutes (default: 20)
  -d t, --delay t       system response delay in seconds (default: 15)
  --sampletime t        temperature sample time in seconds (default: 5)
  --volume V            kettle content volume in liters (default: 70)
  --diameter d          kettle diameter in cm (default: 50)
  --power P             heater power in kW (default: 6)
  --heatloss x          kettle heat loss factor (default: 1)
  --minout x            minimum PID controller output (default: 0)
  --maxout x            maximum PID controller output (default: 100)

Installation

1. Install git and python3
2. Clone this repository:
   git clone https://github.com/hirschmann/pid-autotune.git
3. Install project dependencies:
   pip install matplotlib

After you have completed these steps, you should be able to run sim.py as shown above. If plots are not shown, you have to configure the matplotlib backend, see What is a backend?