URDF <gpio> component state interface "initial_value" param not getting read.

[Nibanovic]

Describe the bug
I've been trying to set up scaled_joint_trajectory_controller for my manipulator, like in UR_robot_driver, and test it using mocked hardware.
To do that, I need a <gpio> component which will hold the scaling_factor value.

Example component:

<gpio name="speed_scaling">
  <state_interface name="speed_scaling_factor">
    <param name="initial_value">1.0</param>
  </state_interface>
</gpio>

When setting the initial_value param, like in <joint> components for example, the param is not getting read.

To Reproduce

1. Add the above component to your <ros2_control> tag in URDF
2. Use mock_components/GenericSystem as hardware
3. Add the speed_scaling_state_broadcaster controller from ur_controllers, which publishes the state interface of the component
4. Launch the ros2_control node, robot_state_publisher node and the speed_scaling_state_broadcaster
5. ros2 topic echo /speed_scaling_state_broadcaster/speed_scaling

Expected behavior
I would expect the topic to echo 100.0, as speed_scaling_state_broadcaster outputs the factor as %.
The actual output is .nan.

More Context
If I change the <gpio> tag to <joint>, so that the component looks like this:

<joint name="speed_scaling">
  <state_interface name="speed_scaling_factor">
    <param name="initial_value">1.0</param>
  </state_interface>
</joint>

... the component behaves as expected with mocked hardware. This leads me to believe that there could be an issue with the way <gpio> param initial value is parsed in the mock_components/GenericSystem

Environment:

• OS: Ubuntu
• Version: Humble -> both ros2_control and ur_controllers packages are humble

[christophfroehlich]

I was not able to reproduce your issue with ros-controls/ros2_control_demos#429, neither on rolling or humble. Can you have a look at this PR, if there is a difference to your configuration?

Btw there is already a test for that

ros2_control/hardware_interface/test/mock_components/test_generic_system.cpp

Lines 1662 to 1679 in 71506d5

	TEST_F(TestGenericSystem, gpio_with_initial_value)
	{
	auto urdf = ros2_control_test_assets::urdf_head + gpio_with_initial_value_ +
	ros2_control_test_assets::urdf_tail;
	TestableResourceManager rm(urdf);
	// Activate components to get all interfaces available
	activate_components(rm, {"GPIOWithInitialValue"});
	// Check interfaces
	EXPECT_EQ(1u, rm.system_components_size());
	ASSERT_EQ(1u, rm.state_interface_keys().size());
	EXPECT_TRUE(rm.state_interface_exists("sample_io/output_1"));
	// Check initial values
	hardware_interface::LoanedStateInterface state = rm.claim_state_interface("sample_io/output_1");
	ASSERT_EQ(1, state.get_value());
	}

[bailaC]

@Nibanovic , will you be able to check this behavior with rolling? I see some code changes around the mock components in rolling. Just asking to verify this behavior on rolling.

[bailaC]

Thank you @christophfroehlich for enhancing example 10. Your changes are working well for me for rolling. Humble yet to be checked.

[bailaC]

Tried your test @christophfroehlich with humble also. Working as expected.

[Nibanovic]

I have rebuilt my packages and retested everything as described in the issue. Funnily enough, now it is working as expected. Thanks for your time, apologies for the non-issue.