Merge branch 'current' into beta
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Jesse Hills
commit
a62f0438fc
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@ -12,6 +12,20 @@ PID controllers are good at modulating an output signal to get a sensor reading
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setpoint. For example, it can be used to modulate the power of a heating unit to get the
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temperature to a user-specified setpoint.
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.. note::
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PID is like cruise control in the cars: it keeps the car's speed constant by continuously
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adjusting the fuel quantity, based on load measurements. Eg when the car has to go up on a hill,
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the system notices the load increase thus immediately gives more fuel to the engine; and when it
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goes down on the other side of the hill, it notices the load decrease thus reduces or cuts off fuel
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completely so that car speed remains as constant as possible. The calculation takes in consideration
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constants like car weight, wind resistance etc.
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This kind of math can be used for a heating or cooling system too, and an auto-tuning algorithm can help
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determining such constants, which mainly describe the heat loss of the room or building. Goal is to
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keep the temperature as constant as possible, and smooth out oscillations otherwise produced by
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classic thermostats.
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Explaining how PID controllers work in detail is out of scope of this documentation entry,
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but there's a nice article explaining the function principle `here <https://blog.opticontrols.com/archives/344>`__.
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@ -110,7 +124,7 @@ To set up a PID climate controller, you need a couple of components:
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.. note::
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The sensor should have a short update interval. The PID update frequency is tied to the update
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interval of the sensor. Set a short ``update_interval`` like ``1s`` on the sensor.
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interval of the sensor. Set a short ``update_interval`` like ``5s`` on the sensor.
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We recommend putting a filter on the sensor (see filters in :doc:`/components/sensor/index`) and
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using ``output_averaging_samples`` to calm the PID sensor from a noisy input sensor.
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@ -210,33 +224,39 @@ To autotune the control parameters:
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ki: 0.0
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kd: 0.0
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2. Create a :doc:`template switch </components/switch/template>` to start autotuning later:
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2. Create a :doc:`template button </components/button/template>` to start autotuning later:
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.. code-block:: yaml
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switch:
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button:
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- platform: template
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name: "PID Climate Autotune"
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turn_on_action:
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on_press:
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- climate.pid.autotune: pid_climate
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3. Compile & Upload the new firmware.
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Now you should have a climate entity called "PID Climate Controller" and a switch called
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"PID Climate Autotune" visible in your frontend of choice.
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Now you should have a climate entity called *PID Climate Controller* and a button called
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*PID Climate Autotune* visible in your frontend of choice.
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The autotune algorithm works by repeatedly switching the heat/cool output to full power and off.
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This induced an oscillation of the observed temperature and the measured period and amplitude
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is automatically calculated.
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This induces an oscillation of the observed temperature and the measured period and amplitude
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is automatically calculated. To do this, it needs to observe at least 3 oscillation cycles.
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But this also means you **have to set the setpoint** of the climate controller to a value the
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device can reach. For example if the temperature of a room is to be controlled, the setpoint needs
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to be above the ambient temperature. If the ambient temperature is 20°C, the setpoint of the
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climate device should be set to at least ~24°C so that an oscillation can be induced.
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.. note::
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4. Set an appropriate setpoint (see above).
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You **have to set the setpoint** of the climate controller to a value the
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device can reach. For example if the temperature of a room is to be controlled, the setpoint needs
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to be above the ambient temperature. If the ambient temperature is 20°C, the setpoint of the
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climate device should be set to at least ~24°C so that an oscillation can be induced.
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Also take care of external influences, like for example when room temperature is severely affected by
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outdoor weather like sun, if it starts to warm up the room in parallel with the heating
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autotune will likely fail or give false results.
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5. Click on the "PID Climate Autotune" and view the logs of the device.
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4. Set an appropriate setpoint (see note above) and turn on the climate controller (Heat, Cool or Auto).
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5. Click the *PID Climate Autotune* button and look at the the logs of the device.
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You should see output like
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@ -250,11 +270,15 @@ climate device should be set to at least ~24°C so that an oscillation can be in
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Detected 5 zero-crossings
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# ...
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For example, in the output above, the autotuner is driving the heating output at 100%
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and trying to reach 24.25 °C.
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.. note::
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This will continue for some time until data for 6 phases (or a bit more, depending on the data
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quality) have been acquired.
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In the output above, the autotuner is driving the heating output at 100% and trying to reach 24.25 °C.
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This will continue for some time until data for 3 phases (6 crossings of the setpoint; or a bit more, depending on
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the data quality) have been acquired.
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The autotune algorithm may take a long time to complete, it depends on the time needed to reproduce the
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heating up and cooling down oscillations the required number of times.
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6. When the PID autotuner has succeeded, output like the one below can be seen:
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@ -264,7 +288,6 @@ climate device should be set to at least ~24°C so that an oscillation can be in
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State: Succeeded!
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All checks passed!
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Calculated PID parameters ("Ziegler-Nichols PID" rule):
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Calculated PID parameters ("Ziegler-Nichols PID" rule):
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control_parameters:
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kp: 0.49460
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@ -272,9 +295,11 @@ climate device should be set to at least ~24°C so that an oscillation can be in
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kd: 12.56301
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Please copy these values into your YAML configuration! They will reset on the next reboot.
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# ...
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Copy the values in ``control_parameters`` into your configuration.
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As soon as the the autotune procedure finishes, the climate starts to work with the calculated parameters
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so that expected operation can be immediately verified.
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If satisfied, copy the values in ``control_parameters`` into your configuration:
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.. code-block:: yaml
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@ -286,10 +311,14 @@ climate device should be set to at least ~24°C so that an oscillation can be in
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ki: 0.00487
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kd: 12.56301
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The *PID Climate Autotune* button can be removed from the config, if the results are satisfactory,
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it's not needed anymore.
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7. Complete, compile & upload the updated firmware.
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If the calculated PID parameters are not good, you can try some of the alternative parameters
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printed below the main control parameters in the log output.
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If the calculated PID parameters are not good, you can try some of the alternative parameters
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printed below the main control parameters in the log output.
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``climate.pid.autotune`` Action
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-------------------------------
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@ -316,9 +345,14 @@ Configuration variables:
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of the PID controller must be able to reach this value. Defaults to ``0.25``.
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- **positive_output** (*Optional*, float): The positive output power to drive the heat output at.
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Defaults to ``1.0``.
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- **negative_output** (*Optional*, float): The positive output power to drive the cool output at.
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- **negative_output** (*Optional*, float): The negative output power to drive the cool output at.
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Defaults to ``-1.0``.
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The ``positive_output`` and ``negative_output`` parameters can be used to compensate the heating or the
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cooling process during the autotune, in the cases when they are not changing the temperature at the
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same rate, resulting in a not symmetrical oscillation. The autotune result will print a message when
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it's recommended to repeat the entire procedure with such parameters configured.
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``climate.pid.set_control_parameters`` Action
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---------------------------------------------
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@ -402,6 +436,7 @@ See Also
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Proceedings of IFAC 9th World Congress, Budapest, 1867-1872
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- :doc:`/components/climate/index`
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- :doc:`/components/output/slow_pwm`
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- `Principles of PID <https://blog.opticontrols.com/archives/344>`__
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- :apiref:`pid/pid_climate.h`
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- :apiref:`PID Autotuner <pid/pid_autotune.h>`
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- :apiref:`PID Autotuner <pid/pid_autotuner.h>`
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- :ghedit:`Edit`
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@ -123,7 +123,7 @@ Home Assistant, as well as starting services in Home Assistant.
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}
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};
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See also :apiclass:`CustomAPIDevice`.
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See also :apiclass:`api::CustomAPIDevice`.
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MQTT Custom Component
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---------------------
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