Filter design tool

[calcmogul]

Is your feature request related to a problem? Please describe.

It's difficult for teams to select and tune filters to meet their signal processing requirements.

Describe the solution you'd like

Features

I'd like to a see a filter design tool akin to the one in MATLAB's DSP toolbox that supports the following:

• Read in sensor data from pre-recorded .wpilog files
• Read in sensor data live over NetworkTables via NT4 topics
• Filter pipeline builder (node-based if there's parts with multiple inputs for a given pipeline stage)
• Export to LinearFilter class coefficients or a code generator
• Common filters like Butterworth, Chebyshev, Elliptical, Band-pass, Notch (could be part of the LinearFilter factory functions) (see https://en.wikipedia.org/wiki/Network_synthesis_filters)
• Building higher order filters from biquad segments
• FFT and/or Morlet wavelets of data to help user determine cutoff frequencies
• Pole placement?
• Show pole-zero map?

UI framework

The DSP parts will need native performance. Options for a GUI framework include:

• Dear ImGUI (what most of our tools use, and provides seamless access to native libraries)
• A web frontend with wpimath cross-compiled to WebAssembly via Emscripten
• Another GUI framework that can invoke native code

Finding long-term maintainers will be an important part of keeping the tool alive. We use Dear ImGUI a lot because many of the active WPILib developers are comfortable with C++. Web technologies are more popular nowadays, but none of the currently active maintainers know those; we'll need to recruit from outside.

Describe alternatives you've considered

A filter base class was suggested in https://github.com/wpilibsuite/allwpilib/issues/5083, but that still requires manual user plumbing to dashboard elements that could be done in a dedicated filter UI instead.

[Starlight220]

Could this be made part of SysId?

[calcmogul]

There's nothing preventing that, but SysId is for a completely different use case. The UI layout requirements will almost certainly be different between the two tools.