Export pid gains as reference by kumar-sanjeeev · Pull Request #2020 · ros-controls/ros2_controllers

kumar-sanjeeev · 2025-11-21T19:39:34Z

This PR includes the following changes:

Added a new parameter export_gain_references to enable or disable the export of gains (p, i, d) as references.
Updated the update_and_write_commands function based on the value of export_gain_references.
Updated test cases for both scenarios i.e export_gain_references=true and export_gain_references=false
Updated the documentation to include the option for exporting PID gains as a reference.

codecov · 2025-11-21T20:08:03Z

Codecov Report

❌ Patch coverage is 68.25397% with 20 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.06%. Comparing base (ec198b1) to head (7c836d3).
⚠️ Report is 53 commits behind head on master.

Files with missing lines	Patch %	Lines
pid_controller/src/pid_controller.cpp	56.81%	15 Missing and 4 partials ⚠️
pid_controller/test/test_pid_controller.cpp	93.75%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2020      +/-   ##
==========================================
- Coverage   85.13%   85.06%   -0.07%     
==========================================
  Files         144      144              
  Lines       13968    14021      +53     
  Branches     1201     1211      +10     
==========================================
+ Hits        11891    11927      +36     
- Misses       1670     1685      +15     
- Partials      407      409       +2

Flag	Coverage Δ
unittests	`85.06% <68.25%> (-0.07%)`	⬇️

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.hpp	`87.50% <ø> (ø)`
..._controller/test/test_pid_controller_preceding.cpp	`100.00% <100.00%> (ø)`
pid_controller/test/test_pid_controller.cpp	`99.45% <93.75%> (-0.55%)`	⬇️
pid_controller/src/pid_controller.cpp	`66.42% <56.81%> (-1.50%)`	⬇️

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christophfroehlich

In principle, this looks fine for me.

christophfroehlich · 2025-11-22T22:10:09Z

pid_controller/src/pid_controller.cpp

+          switch (gain_type)
+          {
+            case 0:  // P gain
+              pids_[i]->set_gains(


Am I missing something? I think there is no functionality to skip setting the gain by passing a NaN value?

@christophfroehlich , you are right. I am thinking of following fix. What do you think ?

Suggested change

pids_[i]->set_gains(

auto current_pid_gains = pids_[i]->get_gains();

for (size_t j = 0; j < GAIN_INTERFACES.size(); ++j)

{

const size_t buffer_index = gains_start_index + i + j * dof_;

const double new_gain_value = reference_interfaces_[buffer_index];

if (std::isfinite(new_gain_value))

{

const size_t gain_type = GAIN_TYPES_INDEX[j];

switch (gain_type)

{

case 0: // P gain

current_pid_gains.p_gain_ = new_gain_value;

pids_[i]->set_gains(current_pid_gains);```

pid_controller/include/pid_controller/pid_controller.hpp

kumar-sanjeeev · 2025-11-24T19:54:37Z

In principle, this looks fine for me.

understood. I am trying to understand one thing, in my current implementation, when I set export_gain_references=true, the reference_interfaces_ vector allocates additional memory for the PID gains for each DOF, as expected:

  if (params_.export_gain_references)
  {
    total_reference_size += dof_ * GAIN_INTERFACES.size();
  }
  reference_interfaces_.resize(total_reference_size, std::numeric_limits<double>::quiet_NaN());

Because of this, some of the existing tests are failing. If this implementation is correct, should I update the tests so that they handle both cases (export_gain_references=true and export_gain_references=false)? Or is there something else I might be missing? Or is there any other recommended way to cater this ?

Test config that I used to reproduce the failure case, along with the corresponding log:

test_pid_controller:
  ros__parameters:
    dof_names:
      - joint1

    command_interface: position

    reference_and_state_interfaces: ["position"]

    export_gain_references: true

    gains:
      joint1: {p: 1.0, i: 2.0, d: 3.0, u_clamp_max: 5.0, u_clamp_min: -5.0}

/workspaces/ros2_control_rolling_dev_docker_ws/src/ros-controls/ros2_controllers/pid_controller/test/test_pid_controller.cpp:88: Failure
Expected equality of these values:
  ref_if_conf.size()
    Which is: 4
  dof_state_values_.size()
    Which is: 1

[  FAILED  ] PidControllerTest.check_exported_interfaces (6 ms)

thedevmystic · 2025-11-25T06:16:26Z

I also think implementation is correct @kumar-sanjeeev,
But if implementation is correct then, why are we failing tests?

Overall, I think some tests need to be updated, but this is just my assumption.

…m value

…onsistency

…rences param

kumar-sanjeeev · 2025-11-26T22:08:48Z

hi @christophfroehlich, I have tried few different ways to fix the ABI check, but still haven’t succeeded. Do you have any recommendations? Or is it okay in this feature request, if it breaks ?

pid_controller/src/pid_controller.cpp

pid_controller/src/pid_controller.yaml

kumar-sanjeeev · 2025-12-11T14:16:29Z

Hi @christophfroehlich,

The implementation is complete from my side. Whenever you have time to review it, please let me know if there is anything I may have missed or should improve.

christophfroehlich

Another quick look and question

christophfroehlich · 2025-12-16T21:25:34Z

pid_controller/src/pid_controller.cpp

+        if (std::isfinite(new_gain_value))
+        {
+          const size_t gain_type = GAIN_TYPES_INDEX[j];
+          switch (gain_type)
+          {
+            case 0:  // P gain
+              current_pid_gains.p_gain_ = new_gain_value;
+              pids_[i]->set_gains(current_pid_gains);
+              break;
+            case 1:  // I gain
+              current_pid_gains.i_gain_ = new_gain_value;
+              pids_[i]->set_gains(current_pid_gains);
+              break;
+            case 2:  // D gain
+              current_pid_gains.d_gain_ = new_gain_value;
+              pids_[i]->set_gains(current_pid_gains);
+              break;
+          }


This is part is not covered by tests. Can you please think of a testcase in doing so? Friending the class and checking pids_ variable might be possible.

Hi @christophfroehlich,

I was on vacation, will look into comments and get back to you

christophfroehlich · 2025-12-16T21:26:59Z

pid_controller/src/pid_controller.yaml

        description: "Individual state publisher activation for each DOF. If true, the controller will publish the state of each DOF to the topic `/<controller_name>/<dof_name>/pid_state`."
      }
+  export_params:
+      gain_references: {


do we really need this parameter? can't they always be exported, and if they are not claimed they just remain nan?

github-actions · 2026-03-16T13:20:41Z

This PR is stale because it has been open for 45 days with no activity. Please tag a maintainer for help on completing this PR, or close it if you think it has become obsolete.

mergify · 2026-03-16T13:21:22Z

This pull request is in conflict. Could you fix it @kumar-sanjeeev?

christophfroehlich · 2026-03-28T13:37:22Z

@kumar-sanjeeev any updates on this?

christophfroehlich reviewed Nov 22, 2025

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thedevmystic reviewed Nov 24, 2025

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pid_controller/include/pid_controller/pid_controller.hpp Outdated Show resolved Hide resolved

kumar-sanjeeev added 6 commits November 26, 2025 18:15

Add bool param to export gains as reference

af1e76f

Add gains to export as references based on export_gain_reference para…

39d9932

…m value

Add export_gain_references param in yaml

4c29c0e

Switch modifier and storage specifier position to maintain codebase c…

d58134f

…onsistency

Do not skip gains by setting them NaN

ff8db06

Update test cases to accomodate for both values of exported_gain_refe…

79473e8

…rences param

kumar-sanjeeev force-pushed the feat-export-pid-gains-as-reference branch from 9914ad5 to 79473e8 Compare November 26, 2025 17:17

kumar-sanjeeev added 2 commits November 26, 2025 21:24

Shift export_gain_references variable to fix abi check

7304887

Add gain references inside new key to pass abi check

5b70746

Fix variable name as per gtest convention

3319cd2

thedevmystic reviewed Nov 27, 2025

View reviewed changes

pid_controller/src/pid_controller.cpp Outdated Show resolved Hide resolved

pid_controller/src/pid_controller.yaml Outdated Show resolved Hide resolved

kumar-sanjeeev added 2 commits November 28, 2025 08:28

Add code review suggestions

1bfe5ef

Update docs with gain reference export possibility

7c836d3

kumar-sanjeeev marked this pull request as ready for review November 28, 2025 08:37

github-actions bot requested review from MarqRazz, bijoua29, destogl, fmauch and mamueluth November 28, 2025 08:37

kumar-sanjeeev changed the title ~~Draf PR : Export pid gains as reference~~ Export pid gains as reference Dec 1, 2025

kumar-sanjeeev requested a review from christophfroehlich December 1, 2025 13:08

christophfroehlich added this to Review triage Dec 16, 2025

christophfroehlich moved this to Needs review in Review triage Dec 16, 2025

christophfroehlich requested changes Dec 16, 2025

View reviewed changes

github-project-automation bot moved this from Needs review to WIP in Review triage Dec 16, 2025

github-actions bot added the stale label Mar 16, 2026

github-actions bot removed the stale label Mar 17, 2026

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