“Issues configuring Dual-IIR PID via MQTT

ip-10

Hi,

I am currently working with the Stabilizer (Dual-IIR application) and I have been trying to configure it for a PID-based control loop. I followed the setup instructions provided in the documentation (https://quartiq.de/stabilizer/setup.html) to establish communication with the device, and I am now using MQTT Explorer to inspect and modify the available topics. I can also interact with the device via the serial interface.

However, I am encountering several issues that I have not been able to resolve with the available documentation:

Some topic values can be modified in MQTT Explorer, but the changes only take effect on the device after performing a store and then issuing a platform reboot via the serial interface. Until the reboot, the device behavior does not reflect the updated values, even though they appear changed in MQTT.
Other topics appear to accept changes in MQTT Explorer, but after performing store and rebooting, they revert to their default values. This makes me suspect that either the format is incorrect or that those fields are not actually writable in the way I am attempting.
In particular, I have been trying to configure the biquad block with typ = "Pid" and adjust its parameters (order, gains, limits, etc.), but I am not confident that my configuration is being correctly interpreted or applied by the firmware.

At this point, I am not sure whether I am misunderstanding part of the configuration model, or if there are constraints or requirements that are not clearly documented. The current documentation provides structural definitions, but it is difficult (at least for me) to understand how to correctly apply them in practice, especially for a control application like a PID loop.

I would like to ask:

Is there a more detailed guide or example on how to properly configure the Dual-IIR application (especially for PID use)?
Are there known constraints on which topics can be modified dynamically vs. those that require specific procedures?
Is there a recommended workflow for applying and validating configuration changes (MQTT vs. serial, store/reboot behavior, etc.)?

Any clarification or example configurations would be greatly appreciated.

Thank you in advance for your help.

rjo

ip-10
The settings are applied in layers, as described in the manual: Defaults < Flash < MQTT retained < MQTT non-retained
If you have retained MQTT messages, they will override the flash settings. You'd have to explain what exactly you are doing.
We have a bunch of hardware in the loop tests that we run. They show how to set up a simple proportional controller:
https://github.com/quartiq/stabilizer/blob/5d7a40dc960a01bd93f0bbd6a86850f5f6265e45/hitl/run.sh#L31-L41

awallin

with the FLS firmware some (all?) PID-parameters take effect only after you write 'None' to update:
e.g. /fls/ch/0/iir/update
I assume it works similarly with dual_iir.

You should be able to set/get parameters over the USB-terminal (easiest?), over ethernet with the command-line miniconf,
e.g. python -m miniconf --broker 192.168.10.3 dt/sinara/fls/80-34-28-5e-bc-e8 ch/1/iir/typ='"Pid"'
(replace IP with your broker, and the parameter path as appropriate) or maybe with MQTT explorer like you do now.

I agree that a howto-guide would be good, and/or simple GUIs for basic use. I made a rough GUI for FLS using nicegui (used with a browser) - if there's interest maybe stabilizer users should collaborate on a GUI (for linux/ubuntu?).

ip-10

Thanks for your insight.

I am using the stabilizer with the MQTT explorer access through a Windows machine. Through the serial connection (a cmd window with python -m serial <port> opened), I have to store the values, some topics get indeed stored in the memory but some others need the platform reboot to be saved ( I guess this is the same as for the 'None' command you mentioned), but some of the topics previously stored return to a default value when rebooting (I don't know if this also happens with other firmware topics, like FLS).

I wanted to used miniconf but was not able to connect to the broker through it, so I stayed with MQTT explorer.

I agree with the GUI idea, the current documentation with Rust has me a bit confused with the actual values I can input to the topics. So I am more incline to think I need to continue discovering the actual values I can input to the different topics.

Tobias

In case it's useful, the oxford ion trappers do have a GUI for stabilizer ( https://github.com/OxfordIonTrapGroup/stabilizer-ui ), though you'll probably have to use their fork of the firmware as well