Derivative smoothing

[TomPcz]

Could you please add an optional derivative smoothing? Noisy input causes jitter in the input. A simple low-pass filter (with user-defined cutoff frequency) would solve it.

[Dlloydev]

I'll look further into this, however, being quite busy, it might take a while to get started. A document that keeps catching my interest is Practical PID Controls, where any enhancement(s) could be done in stages:

1. Removing Command Glitches from Derivative Response
2. Averaging filter
3. Single pole filter (as your suggestion)

I'm not sure if item 1 is an issue ... it'll take some testing (and so will 2 and 3).

[gmarquart]

@tpikalek -- why not try an existing filtering library? e.g., https://www.megunolink.com/articles/coding/3-methods-filter-noisy-arduino-measurements/

[Dlloydev]

Removed the "enhancement" label as there will be no time in the near term to work on this. Also having second thoughts as to how it may affect PID performance and as @tpikalek points out, an external filtering library could be an alternative. I'll leave this open for now as there could be more discussion.

[gmarquart]

e.g., using ExponentialFilter from aforementioned library to smooth the temp prior to feeding into QuickPID