Epidaurus 0.2.0

PID based room temperature controller - to be used in combination with pelops/copreus, pelops/argaeus and pelops/alcathous.

Ἐπίδαυρος [1] is a PID based room temperature controller - to be used in combination with pelops/copreus, pelops/argaeus and pelops/alcathous.

Pelops Overview

Epidaurus is part of the collection of mqtt based microservices pelops. An overview on the microservice architecture and examples can be found at (http://gitlab.com/pelops/pelops).

For Users

Installation Core-Functionality

Prerequisites for the core functionality are:

sudo apt install python3 python3-pip
sudo pip3 install paho-mqtt pyyaml pelops

Install via pip:

sudo pip3 install epidaurus

To update to the latest version add --upgrade as prefix to the pip3 line above.

Install via gitlab (might need additional packages):

git clone [e-mail]:pelops/epidaurus.git
cd epidaurus
sudo python3 setup.py install

This will install the following shell scripts: * epidaurus

The script cli arguments are: * ‘-c’/’–config’ - config file (mandatory) * ‘-v’ - verbose output (optional) * ‘–version’ - show the version number and exit

YAML-Config

A yaml [2] file must contain four root blocks: * mqtt - mqtt-address, mqtt-port, and path to credentials file credentials-file (a file consisting of two entries: mqtt-user, mqtt-password) * logger - which log level and which file to be used * controller - parameters for the controller and the embedded pid

mqtt:
    mqtt-address: localhost
    mqtt-port: 1883
    credentials-file: ~/credentials.yaml
    log-level: INFO

logger:
    log-level: DEBUG  # DEBUG, INFO, WARNING, ERROR, CRITICAL
    log-file: test_epidaurus.log

controller:
    value-idle: 4.5  # idle mode output - heating system does nothing
    value-min: 5  # minimum output for active (=heating) system
    value-max: 23  # maximum value for heater
    pid-max-output: 500  # for normalization purposes. this is the expected maximum output of the pid controller
    idle-mode-threshold: 0.75  # if temperature is this value above set-point, set output to volt-idle value.
    topics-sub:
        set-point: /test/thermostat/set-point  # receive new set point via this topic
        input:     /test/thermostat/input  # receive input (=temperature) updates via this topic
    topics-pub:
        output: /test/thermostat/output  # publish resulting output voltage to this topic
    pid:
        p-gain: 75
        i-gain: 20
        d-gain: 0
        update-interval: 30  # in seconds (in fact not used anywhere)
        windup-guard: 20  # protect integral term from windup

systemd

• add systemd example.

For Developers

Getting Started

The project consists of two main modules: * pid - classic pid-implementation * controller - wraps around the pid and adds thermostat related behavior like minimum output, idle output, normalization of pid output to expected voltage range.

The values for pid and some for controller must be determined using experiments with the real system. To get a first set of parameters you can use tests/test_controller_model_nomqtt.py together with tools/model_trivial_flat.py.

Todos

• Auto parameterization of pid

• …

Misc

The code is written for python3 (and tested with python 3.5 on an Raspberry Pi Zero with Raspbian Stretch).

Merge requests / bug reports are always welcome.

[1]

The icon used for this project is not Epidaurus, son of pelops.

[2]

Currently, pyyaml is yaml 1.1 compliant. In pyyaml On/Off and Yes/No are automatically converted to True/False. This is an unwanted behavior and deprecated in yaml 1.2. In copreus this autoconversion is removed. Thus, On/Off and Yes/No are read from the yaml file as strings (see module baseclasses.myconfigtools).