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enter image description hereQuestion edit Latest (09-Apr):

I wrote my own custom hardware interface called dig_cont (actuator interface and sensor interface) and I am able to compile and run successfully. I can see two different topic for dig_cont which is my actuator and sensor I have interfaced with. It has two different topics as shown. So I am going to send my microcontroller, a trigger signal to actuate and it gives a feedback back to the interface with its state. I did not implement a GPIO instead, I chose to send the trigger as velocity and receive its position for my actuator.

  1. I want to know which topic my sensor feedback updates to? All I can see is two different topics for dig_cont. I believe the trigger signal should be updated through /dig_cont/commands, am I right?

  2. Why is my controller name dig_cont not visible in rqt graph similar to diff_cont. Maybe It is not configured properly?

Feed:

ubuntu@MobileRobot:~/ros2_ws$ ros2 launch dandebot_description launch_robot.launch.py 
[INFO] [launch]: All log files can be found below /home/ubuntu/.ros/log/2024-04-09-09-41-49-037336-MobileRobot-19687
[INFO] [launch]: Default logging verbosity is set to INFO
[INFO] [robot_state_publisher-1]: process started with pid [19691]
[INFO] [twist_mux-2]: process started with pid [19693]
[twist_mux-2] [INFO] [1712670109.378276539] [twist_mux]: Topic handler 'topics.joystick' subscribed to topic 'cmd_vel_joy': timeout = 0.500000s , priority = 100.
[twist_mux-2] [INFO] [1712670109.379431617] [twist_mux]: Topic handler 'topics.navigation' subscribed to topic 'cmd_vel': timeout = 0.500000s , priority = 10.
[twist_mux-2] [INFO] [1712670109.379640602] [twist_mux]: Topic handler 'topics.servo' subscribed to topic 'cmd_vel_servo': timeout = 0.500000s , priority = 100.
[robot_state_publisher-1] [WARN] [1712670109.389885430] [kdl_parser]: The root link base_link has an inertia specified in the URDF, but KDL does not support a root link with an inertia.  As a workaround, you can add an extra dummy link to your URDF.
[robot_state_publisher-1] [INFO] [1712670109.389953062] [robot_state_publisher]: got segment base_footprint
[robot_state_publisher-1] [INFO] [1712670109.390011924] [robot_state_publisher]: got segment base_link
[robot_state_publisher-1] [INFO] [1712670109.390018656] [robot_state_publisher]: got segment camera_1
[robot_state_publisher-1] [INFO] [1712670109.390037998] [robot_state_publisher]: got segment digging_frame
[robot_state_publisher-1] [INFO] [1712670109.390042987] [robot_state_publisher]: got segment laser_1
[robot_state_publisher-1] [INFO] [1712670109.390060360] [robot_state_publisher]: got segment leftwheel_1
[robot_state_publisher-1] [INFO] [1712670109.390064929] [robot_state_publisher]: got segment rightwheel_1
[INFO] [ros2_control_node-3]: process started with pid [19753]
[INFO] [spawner-4]: process started with pid [19755]
[INFO] [spawner-5]: process started with pid [19757]
[INFO] [spawner-6]: process started with pid [19759]
[ros2_control_node-3] [WARN] [1712670114.992177586] [controller_manager]: [Deprecated] Passing the robot description parameter directly to the control_manager node is deprecated. Use '~/robot_description' topic from 'robot_state_publisher' instead.
[ros2_control_node-3] [INFO] [1712670114.992538295] [resource_manager]: Loading hardware 'dandebot' 
[ros2_control_node-3] [INFO] [1712670114.993326592] [resource_manager]: Initialize hardware 'dandebot' 
[ros2_control_node-3] [INFO] [1712670114.993509170] [DiffDriveArduino]: Configuring...
[ros2_control_node-3] [INFO] [1712670114.993793225] [DiffDriveArduino]: Finished Configuration
[ros2_control_node-3] [INFO] [1712670114.993806448] [resource_manager]: Successful initialization of hardware 'dandebot'
[ros2_control_node-3] [INFO] [1712670114.993948738] [resource_manager]: Loading hardware 'DigController' 
[ros2_control_node-3] [INFO] [1712670114.994726613] [resource_manager]: Initialize hardware 'DigController' 
[ros2_control_node-3] [INFO] [1712670114.994902467] [DigController]: Configuring Actuators...
[ros2_control_node-3] [INFO] [1712670114.995134096] [DigController]: Finished Initializing Actuators...
[ros2_control_node-3] [INFO] [1712670114.995145271] [resource_manager]: Successful initialization of hardware 'DigController'
[ros2_control_node-3] [INFO] [1712670114.995218957] [resource_manager]: Loading hardware 'DigControllerFeedback' 
[ros2_control_node-3] [INFO] [1712670114.995309343] [resource_manager]: Initialize hardware 'DigControllerFeedback' 
[ros2_control_node-3] [INFO] [1712670114.995330207] [DigControllerFeedback]: Configuring Sensors...
[ros2_control_node-3] [INFO] [1712670114.995450199] [DigControllerFeedback]: Finished Initializing Sensors..
[ros2_control_node-3] [INFO] [1712670114.995459131] [resource_manager]: Successful initialization of hardware 'DigControllerFeedback'
[ros2_control_node-3] [INFO] [1712670114.995547155] [resource_manager]: 'configure' hardware 'DigControllerFeedback' 
[ros2_control_node-3] [INFO] [1712670114.995563933] [DigControllerFeedback]: Configuration successful.
[ros2_control_node-3] [INFO] [1712670114.995571543] [resource_manager]: Successful 'configure' of hardware 'DigControllerFeedback'
[ros2_control_node-3] [INFO] [1712670114.995578865] [resource_manager]: 'activate' hardware 'DigControllerFeedback' 
[ros2_control_node-3] [INFO] [1712670114.995585923] [DigControllerFeedback]: Successfully activated!
[ros2_control_node-3] [INFO] [1712670114.995592717] [resource_manager]: Successful 'activate' of hardware 'DigControllerFeedback'
[ros2_control_node-3] [INFO] [1712670114.995601682] [resource_manager]: 'configure' hardware 'DigController' 
[ros2_control_node-3] [INFO] [1712670114.995608454] [resource_manager]: Successful 'configure' of hardware 'DigController'
[ros2_control_node-3] [INFO] [1712670114.995615749] [resource_manager]: 'activate' hardware 'DigController' 
[ros2_control_node-3] [INFO] [1712670114.995621898] [DigController]: Activating Dig Controller...
[ros2_control_node-3] [INFO] [1712670114.995784003] [resource_manager]: Successful 'activate' of hardware 'DigController'
[ros2_control_node-3] [INFO] [1712670114.995798048] [resource_manager]: 'configure' hardware 'dandebot' 
[ros2_control_node-3] [INFO] [1712670114.995805810] [resource_manager]: Successful 'configure' of hardware 'dandebot'
[ros2_control_node-3] [INFO] [1712670114.995813479] [resource_manager]: 'activate' hardware 'dandebot' 
[ros2_control_node-3] [INFO] [1712670114.995820061] [DiffDriveArduino]: Starting Controller...
[ros2_control_node-3] [INFO] [1712670115.004922170] [resource_manager]: Successful 'activate' of hardware 'dandebot'
[ros2_control_node-3] [INFO] [1712670115.012059746] [controller_manager]: update rate is 30 Hz
[ros2_control_node-3] [INFO] [1712670115.012235157] [controller_manager]: RT kernel is recommended for better performance
[ros2_control_node-3] [INFO] [1712670115.306154682] [controller_manager]: Loading controller 'joint_broad'
[spawner-4] [INFO] [1712670115.363645812] [spawner_joint_broad]: Loaded joint_broad
[ros2_control_node-3] [INFO] [1712670115.364885662] [controller_manager]: Configuring controller 'joint_broad'
[ros2_control_node-3] [INFO] [1712670115.365000558] [joint_broad]: 'joints' or 'interfaces' parameter is empty. All available state interfaces will be published
[spawner-4] [INFO] [1712670115.446832382] [spawner_joint_broad]: Configured and activated joint_broad
[ros2_control_node-3] [INFO] [1712670115.538087962] [controller_manager]: Loading controller 'diff_cont'
[spawner-6] [INFO] [1712670115.580553490] [spawner_diff_cont]: Loaded diff_cont
[ros2_control_node-3] [INFO] [1712670115.581333953] [controller_manager]: Loading controller 'dig_cont'
[INFO] [spawner-4]: process has finished cleanly [pid 19755]
[ros2_control_node-3] [INFO] [1712670115.613354313] [controller_manager]: Configuring controller 'diff_cont'
[spawner-5] [INFO] [1712670115.614195053] [spawner_dig_cont]: Loaded dig_cont
[ros2_control_node-3] [INFO] [1712670115.646575217] [controller_manager]: Configuring controller 'dig_cont'
[ros2_control_node-3] [INFO] [1712670115.648069760] [dig_cont]: configure successful
[spawner-6] [INFO] [1712670115.747167790] [spawner_diff_cont]: Configured and activated diff_cont
[ros2_control_node-3] [INFO] [1712670115.779496946] [dig_cont]: activate successful
[spawner-5] [INFO] [1712670115.813855217] [spawner_dig_cont]: Configured and activated dig_cont
[INFO] [spawner-6]: process has finished cleanly [pid 19759]
[INFO] [spawner-5]: process has finished cleanly [pid 19757]

Status:


ros2 topic list
/cmd_vel
/cmd_vel_joy
/cmd_vel_servo
/diagnostics
/diff_cont/cmd_vel_unstamped
/diff_cont/odom
/diff_cont/transition_event
/dig_cont/commands
/dig_cont/transition_event
/dynamic_joint_states
/joint_broad/transition_event
/joint_states
/parameter_events
/robot_description
/rosout
/tf
/tf_static

Command Interfaces:
    dig_to_base_link/velocity [available] [claimed]
    leftwheel_to_base_link/velocity [available] [claimed]
    rightwheel_to_base_link/velocity [available] [claimed]
state interfaces
    dig_to_base_link/position
    leftwheel_to_base_link/position
    leftwheel_to_base_link/velocity
    rightwheel_to_base_link/position
    rightwheel_to_base_link/velocity



ubuntu@MobileRobot:~$ ros2 control list_hardware_components
Hardware Component 1
    name: DigControllerFeedback
    type: sensor
    plugin name: dig_controller/DigControllerFeedback
    state: id=3 label=active
    command interfaces
Hardware Component 2
    name: DigController
    type: actuator
    plugin name: dig_controller/DigController
    state: id=3 label=active
    command interfaces
        dig_to_base_link/velocity [available] [claimed]
Hardware Component 3
    name: dandebot
    type: system
    plugin name: diffdrive_arduino/DiffDriveArduino
    state: id=3 label=active
    command interfaces
        leftwheel_to_base_link/velocity [available] [claimed]
        rightwheel_to_base_link/velocity [available] [claimed]


Controller yaml:

controller_manager:
  ros__parameters:
    update_rate: 30
    # use_sim_time: true

    diff_cont:
      type: diff_drive_controller/DiffDriveController

    joint_broad:
      type: joint_state_broadcaster/JointStateBroadcaster

    dig_cont:
      type: forward_command_controller/ForwardCommandController

dig_cont:
  ros__parameters:

    publish_rate: 30.0
    joints:
      - dig_to_base_link
      
    interface_name: velocity

diff_cont:
  ros__parameters:

    publish_rate: 30.0

    base_frame_id: base_link

    left_wheel_names: ['leftwheel_to_base_link']
    right_wheel_names: ['rightwheel_to_base_link']
    wheel_separation: 0.65
    wheel_radius: 0.1692

    use_stamped_vel: false

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  • $\begingroup$ please don't fully rewrite your question, this is not the sense of this forum. but see my updated answer below $\endgroup$ Apr 7 at 6:09

1 Answer 1

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The typical ros2_control approach is to write a controller to interact (from ROS via topics, services) with the hardware component. Have a look at this example of a GPIO controller.

It seems that you have mixed controllers and hardware components. Why are you calling your hardware component (derived from actuator interface) "dig_controller"? The pluginlib error comes from the controller_manager, which obviously can't load your hardware component as a controller.

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  • $\begingroup$ Thank you for your quick reply. The problem was the type in my controller yaml file where I chose digController instead of Forward command controller so it was not able to link up. However, when I try to read and write something, I print the received variables and the ones I send, but it doesn't print anything. How do you think my approach towards this should be? $\endgroup$ Apr 7 at 17:39
  • $\begingroup$ If you see my read and write function in my cpp file, you will see how I print it. It works for all the other cpp nodes but it doesn't for this. Am I doing something wrong here? Does that mean that my read and write functions are not really executed? $\endgroup$ Apr 7 at 17:40
  • $\begingroup$ Introspect your system with ros2controlcli: Are the interface claimed? If nothing is claiming the interfaces of your hardware, the read/write method might not get called. $\endgroup$ Apr 7 at 18:03
  • $\begingroup$ Yes they are claimed after I changed the type in my yaml file: ubuntu@MobileRobot:~/ros2_ws$ ros2 control list_hardware_interfaces command interfaces dig_to_base_link/velocity [available] [claimed] leftwheel_to_base_link/velocity [available] [claimed] rightwheel_to_base_link/velocity [available] [claimed] state interfaces dig_to_base_link/position leftwheel_to_base_link/position leftwheel_to_base_link/velocity rightwheel_to_base_link/position rightwheel_to_base_link/velocity $\endgroup$ Apr 7 at 18:18
  • $\begingroup$ I am sure that something is wrong. I have added the rqt_graph of what's going on in the post. The topic /dig_cont seems to be inactive $\endgroup$ Apr 7 at 19:04

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