Modify I-Component (not Ki) of PID during roast?

[peterz1972]

Hi, I hope, this is the right place for a question like this...

I would like to start experimenting with PID control on my production roaster. I want to use the Software PID from Artisan.

Is it possible during the roast to manually set the I-component (not Ki) from the PID, for example via a button or an alert, to a specific value, respectively to reduce it by a certain amount?

The background is that I currently run my roast curves very reproducibly using the Alarms, by setting gas and air depending on BT.
But of course, there are always small deviations. Now I would like to get those under control with the help of a PID as an additional tool.

That means I would like to continue defining my roast curve using Alarms, but additionally activate the PID (following the background curve). Each time I normally reduce the gas to a certain value at a specific BT, or decrease it by a certain amount, I would no longer do this directly via the gas control, but instead simply reducing the I-component by that same amount.

I do not want to leave the entire roast to a PID. Until I find the right parameters (if I ever do), I am afraid quite a few batches would go down the drain.

Regards
Peter, dunkelhell.at

[MAKOMO]

In PID control theory, I is a computed value which drives the resulting PID duty together with P and D, respecting the PID parameters Kp, Ki and Kd. What you describe sounds far away from traditional PID closed control loop (which is well studied in control theory) and requires a separate implementation. Lucky you that Artisan is open-source and you can modify it in any way you want!

[peterz1972]

Hm... Let's stick to the traditional PID closed control loop then.
Is there a possibility yet for doing something like "Feedforward", anticipating known disturbances at some points within the roast before they occur?
I.e. decrease or increase the output value after the PID before it gets feeded to the Burner Slider (for doing Scott Rao's "Gas dip method" for example).

As an idea … a kind of Offset setting within the PID Control Output section which can also be manipulated via Buttons, Alarms, …
Maybe it is already there, but I just don’t see it?