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[pidcontroller] Implement previous state recovery on startup (#13003)

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* [pidcontroller] Implement previous state recovery on startup

This feature allows the PID controller parameters to be updated and
OpenHAB to be restarted without losing the current controller state.

This is especially important for systems with a long response time.
For example it might take up to a day for an underfloor heating
controller to stabilise after losing state and having to build up
the integrator value from zero.

Signed-off-by: Lenno Nagel <lenno@nagel.ee>

* Change logger.info -> logger.debug

Signed-off-by: Lenno Nagel <lenno@nagel.ee>

* Change debug Item -> inspector Item in README

Signed-off-by: Lenno Nagel <lenno@nagel.ee>

* Add documentation regarding state persistence

Signed-off-by: Lenno Nagel <lenno@nagel.ee>

* Update bundles/org.openhab.automation.pidcontroller/README.md

Signed-off-by: Fabian Wolter <github@fabian-wolter.de>

* Update bundles/org.openhab.automation.pidcontroller/README.md

Signed-off-by: Fabian Wolter <github@fabian-wolter.de>

Co-authored-by: Fabian Wolter <github@fabian-wolter.de>
This commit is contained in:
Lenno Nagel
2022-07-02 12:28:18 +03:00
committed by GitHub
parent b886650bae
commit 2c919c6a38
3 changed files with 63 additions and 12 deletions
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25
bundles/org.openhab.automation.pidcontroller/README.md
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@@ -35,14 +35,14 @@ This is then transferred to the action module.
| `ki` | Decimal | I: [Integral Gain](#integral-i-gain-parameter) Parameter | Y |
| `kd` | Decimal | D: [Derivative Gain](#derivative-d-gain-parameter) Parameter | Y |
| `kdTimeConstant` | Decimal | D-T1: [Derivative Gain Time Constant](#derivative-time-constant-d-t1-parameter) in sec. | Y |
| `commandItem` | String | Send a String "RESET" to this item to reset the I- and the D-part to 0. | N |
| `commandItem` | String | Send a String "RESET" to this item to reset the I- and the D-part to 0. | N |
| `loopTime` | Decimal | The interval the output value will be updated in milliseconds. Note: the output will also be updated when the input value or the setpoint changes. | Y |
| `integralMinValue` | Decimal | The I-part will be limited (min) to this value. | N |
| `integralMaxValue` | Decimal | The I-part will be limited (max) to this value. | N |
| `pInspector` | Item | Name of the debug Item for the current P-part | N |
| `iInspector` | Item | Name of the debug Item for the current I-part | N |
| `dInspector` | Item | Name of the debug Item for the current D-part | N |
| `eInspector` | Item | Name of the debug Item for the current regulation difference (error) | N |
| `integralMinValue` | Decimal | The I-part will be limited (min) to this value. | N |
| `integralMaxValue` | Decimal | The I-part will be limited (max) to this value. | N |
| `pInspector` | Item | Name of the inspector Item for the current P-part | N |
| `iInspector` | Item | Name of the inspector Item for the current I-part | N |
| `dInspector` | Item | Name of the inspector Item for the current D-part | N |
| `eInspector` | Item | Name of the inspector Item for the current regulation difference (error) | N |
The `loopTime` should be max a tenth of the system response.
E.g. the heating needs 10 min to heat up the room, the loop time should be max 1 min.
@@ -57,6 +57,9 @@ You can view the internal P-, I- and D-parts of the controller with the inspecto
These values are useful when tuning the controller.
They are updated every time the output is updated.
Inspector items are also used to recover the controller's previous state during startup. This feature allows the PID
controller parameters to be updated and openHAB to be restarted without losing the current controller state.
## Proportional (P) Gain Parameter
Parameter: `kp`
@@ -135,3 +138,11 @@ This can be done either by changing the setpoint (e.g. 20°C -> 25°C) or by for
This process can take some time with slow responding control loops like heating systems.
You will get faster results with constant lighting or PV zero export applications.
## Persisting controller state across restarts
Persisting controller state requires inspector items `iInspector`, `dInspector`, `eInspector` to be configured.
The PID controller uses these Items to expose internal state in order to restore it during startup or reload.
In addition, you need to have persistence set up for these items in openHAB. Please see openHAB documentation regarding
[Persistence](https://www.openhab.org/docs/configuration/persistence.html) for more details and instructions.