Signal interoperability

The examples below show how signal translator components included in the core components can be used with a selection of common ROS message types for interoperability.

tip

If you haven't done so already, review the corresponding concepts page first.

AICA signals to standard ROS messages

This example uses the Joint Signal To Joint State Message component to translate the joint state output from the hardware interface to a sensor_msgs::msg::JointState message and the Cartesian Signal to Pose Stamped Message component to translate the Cartesian state output to a geometry_msgs::msg::PoseStamped message.

With the application loaded and playing, the two components will publish the converted message on their output signal each time a new message is received from the hardware interface. A jsonified version of those messages can be observed in the live topic view.

With content

{
  "header": { "stamp": { "sec": 1749019367, "nanosec": 736960997 }, "frame_id": "world" },
  "pose": {
    "position": { "x": 0.37246365888399174, "y": 0.048146868357851064, "z": 0.4299999920960212 },
    "orientation": {
      "x": 0.7073880448768991,
      "y": 0.7068251811053661,
      "z": 8.971607761328708e-7,
      "w": -0.0005633114591638605
    }
  }
}

With content

{
  "header": { "stamp": { "sec": 1749019239, "nanosec": 277825301 }, "frame_id": "" },
  "name": ["joint_0", "joint_1", "joint_2", "joint_3", "joint_4", "joint_5"],
  "position": [0, 0, 0, 0, 0, 0],
  "velocity": [0, 0, 0, 0, 0, 0],
  "effort": [0, 0, 0, 0, 0, 0]
}

Application YAML

schema: 2-0-4
dependencies:
  core: v4.3.2
on_start:
  load:
    hardware: hardware
components:
  joint_signal_to_joint_state_message:
    component: aica_core_components::ros::JointSignalToJointStateMsg
    display_name: Joint Signal To Joint State Message
    inputs:
      input: /hardware/robot_state_broadcaster/joint_state
  cartesian_signal_to_pose_stamped_message:
    component: aica_core_components::ros::CartesianSignalToPoseStampedMsg
    display_name: Cartesian Signal To Pose Stamped Message
    inputs:
      input: /hardware/robot_state_broadcaster/cartesian_state
hardware:
  hardware:
    display_name: Hardware Interface
    urdf: Generic six-axis robot arm
    rate: 100
    events:
      transitions:
        on_load:
          load:
            controller: robot_state_broadcaster
            hardware: hardware
    controllers:
      robot_state_broadcaster:
        plugin: aica_core_controllers/RobotStateBroadcaster
        outputs:
          joint_state: /hardware/robot_state_broadcaster/joint_state
          cartesian_state: /hardware/robot_state_broadcaster/cartesian_state
        events:
          transitions:
            on_load:
              switch_controllers:
                hardware: hardware
                activate: robot_state_broadcaster
            on_activate:
              load:
                - component: cartesian_signal_to_pose_stamped_message
                - component: joint_signal_to_joint_state_message
graph:
  positions:
    components:
      joint_signal_to_joint_state_message:
        x: 200
        y: 880
      cartesian_signal_to_pose_stamped_message:
        x: 200
        y: 660
    hardware:
      hardware:
        x: 200
        y: -20
  edges:
    hardware_hardware_robot_state_broadcaster_on_activate_cartesian_signal_to_pose_stamped_message_cartesian_signal_to_pose_stamped_message:
      path:
        - x: 80
          y: 400
        - x: 80
          y: 720
    hardware_hardware_robot_state_broadcaster_on_activate_joint_signal_to_joint_state_message_joint_signal_to_joint_state_message:
      path:
        - x: -20
          y: 400
        - x: -20
          y: 940
    hardware_hardware_robot_state_broadcaster_joint_state_joint_signal_to_joint_state_message_input:
      path:
        - x: 120
          y: 520
        - x: 120
          y: 1060
    hardware_hardware_robot_state_broadcaster_cartesian_state_cartesian_signal_to_pose_stamped_message_input:
      path:
        - x: 140
          y: 560
        - x: 140
          y: 840

Standard ROS messages to AICA signals

Mirroring the first example, this application uses the Wrench Stamped Message To Cartesian Signal component to translate a geometry_msgs::msg::WrenchStamped from some custom component to a Cartesian signal that is connected to the force controller of the hardware interface.

note

The custom component is just an example placeholder in for any implementation that has a ROS standard message output, which might occur when porting existing ROS nodes into AICA Studio using the Component SDK.

Application YAML

schema: 2-0-4
dependencies:
  core: v4.3.2
on_start:
  load:
    hardware: hardware
components:
  wrench_stamped_message_to_cartesian_signal:
    component: aica_core_components::ros::WrenchStampedMsgToCartesianSignal
    display_name: Wrench Stamped Message To Cartesian Signal
    events:
      transitions:
        on_load:
          switch_controllers:
            hardware: hardware
            activate: force_controller
    inputs:
      input: /custom_motion_generator/command
    outputs:
      output: /wrench_stamped_message_to_cartesian_signal/output
  custom_motion_generator:
    component: template_component_package::PyComponent
    display_name: Custom Motion Generator
    events:
      transitions:
        on_load:
          load:
            component: wrench_stamped_message_to_cartesian_signal
    outputs:
      command: /custom_motion_generator/command
hardware:
  hardware:
    display_name: Hardware Interface
    urdf: Generic six-axis robot arm
    rate: 100
    events:
      transitions:
        on_load:
          load:
            - controller: robot_state_broadcaster
              hardware: hardware
            - controller: force_controller
              hardware: hardware
    controllers:
      robot_state_broadcaster:
        plugin: aica_core_controllers/RobotStateBroadcaster
        events:
          transitions:
            on_load:
              switch_controllers:
                hardware: hardware
                activate: robot_state_broadcaster
            on_activate:
              load:
                component: custom_motion_generator
      force_controller:
        plugin: aica_core_controllers/effort/ForceController
        parameters:
          force_limit:
            - !!float 20.0
            - !!float 20.0
            - !!float 20.0
            - !!float 2.0
            - !!float 2.0
            - !!float 2.0
        inputs:
          command: /wrench_stamped_message_to_cartesian_signal/output
graph:
  positions:
    components:
      wrench_stamped_message_to_cartesian_signal:
        x: 100
        y: 780
      custom_motion_generator:
        x: 100
        y: 420
    hardware:
      hardware:
        x: 680
        y: -20
  edges:
    wrench_stamped_message_to_cartesian_signal_output_hardware_hardware_force_controller_command:
      path:
        - x: 660
          y: 1040
        - x: 660
          y: 820
    wrench_stamped_message_to_cartesian_signal_on_load_hardware_hardware_force_controller:
      path:
        - x: 580
          y: 920
        - x: 580
          y: 660
    hardware_hardware_robot_state_broadcaster_on_activate_custom_motion_generator_custom_motion_generator:
      path:
        - x: 40
          y: 400
        - x: 40
          y: 480
    custom_motion_generator_on_load_wrench_stamped_message_to_cartesian_signal_wrench_stamped_message_to_cartesian_signal:
      path:
        - x: 540
          y: 560
        - x: 540
          y: 740
        - x: 40
          y: 740
        - x: 40
          y: 840
    custom_motion_generator_command_wrench_stamped_message_to_cartesian_signal_input:
      path:
        - x: 500
          y: 680
        - x: 500
          y: 760
        - x: 80
          y: 760
        - x: 80
          y: 1040