use gz-physics#283 to implement joint_states/effort feedback (backport #186)

[christophfroehlich]

Fixes joint_states/effort being zero for joints with <state_interface name="effort" /> in combination with joint_state_broadcaster/JointStateBroadcaster by using the JointTransmittedWrench component introduced by gazebosim/gz-physics#283.

The joint axis is hard coded to z. I did not yet look into reading out the actual <axis> of the joint and extracting the respective force/torque component of the wrench.

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This is an automatic backport of pull request #186 done by Mergify.

[christophfroehlich]

@federicociresola can you please test this? do you use fortress or harmonic? The backport for fortress was not straight forward because of the introduction of gz::physics::Vector3d, but it seems to work now (i.e, it compiles. haven't further tested it)

[federicociresola]

I have tested the branch and it seems to work for Gz Harmonic @christophfroehlich

I tested it on

• Ubuntu 22.04 LTS
• ROS2 Humble
• Gazebo Harmonic
  and I used the cart effort example as follows:

# Terminal 1
ros2 launch gz_ros2_control_demos cart_example_effort.launch.py

# Terminal 2
ros2 run gz_ros2_control_demos example_effort

# Terminal 3
ros2 topic echo /joint_states

In addition while I was testing the branch ,I noticed that the effort state was published even through it wasn't include in the state _interfaces of the configuration file such as the cart_controller_effort.yaml. I don't think this is normal behavior, do you?

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