I was thinking about implementing a custom controller for my setting but I'm not sure about which of the header files in firmware headers to include and/or inherit from as I can't find their related documentation nor comments inside the headers.

Looking at the controllers' implementation (in implementation it is still not clear how to decide with of the headers to inherit from. For example PIDController inherits from IUpdateble. Meanwhile PositionController inherits from IGoal and IAxisController, and therefore inherits indirectly from inherits from IUpdateble.

To wrap up my question is why is there no documentation at all, or is it located somewhere else? Also references to paper used in the code should be at least referenced.