Add derivative filter and discretization methods

[ViktorCVS]

Overview

Add a first-order derivative filter and selectable discretization methods for the I and D paths, keeping previous behavior as the default.

What was added/changed in this PR

• Derivative filter (D path): added derivative_filter_time (seconds) in gains.__map_dof_names.
  Continuous form: C_D(s) = D * s / (1 + s * derivative_filter_time). Default 0.0 preserves the prior (unfiltered) behavior; non-negative validation.

• Discretization methods: added per-DOF options

  • integration_method: forward_euler (default), backward_euler, trapezoidal (Tustin).
  • derivative_method: forward_euler (default), backward_euler, trapezoidal (Tustin).
    Defaults match the previous implicit scheme, so existing setups remain unchanged unless these parameters are set.

About tests

Builds cleanly and passes pre-commit and colcon test.

About change in tests

Added PidControllerTest.all_parameters_set_configure_success_full_gains, which loads test_pid_controller_full_gains, asserts successful on_configure(...), and verifies parsing/mapping of all standard fields plus the new derivative_filter_time, integration_method, and derivative_method values.

Related PR's

• Add derivative filter and discretization control_toolbox#471

Final notes

I'm very open to any recommendations to improve this code.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.26%. Comparing base (9ce90ba) to head (30b8e73).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1909   +/-   ##
=======================================
  Coverage   85.25%   85.26%           
=======================================
  Files         143      143           
  Lines       13794    13801    +7     
  Branches     1197     1198    +1     
=======================================
+ Hits        11760    11767    +7     
  Misses       1636     1636           
  Partials      398      398           

Flag	Coverage Δ
unittests	85.26% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
pid_controller/test/test_pid_controller.cpp	100.00% <100.00%> (ø)
pid_controller/test/test_pid_controller.hpp	86.66% <ø> (ø)

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[christophfroehlich]

Thanks for the follow-up. But this feature is not yet included in the PID class, right?

[ViktorCVS]

Contributor

still not, I'll add a warning in the PR description