Trying to integrate a CANopen motor

[VerlooyNick]

I'm trying to run a Nanotec motor through the ros2_canopen stack. Following the documentation and trinamic tutorial, I'm able to init, start and stop the motor by using the service calls. Now I'm looking for the next step: integrate the motor into my mobile robot. Therefore, I expected the /target topic to be available to publish to. This is not the case, I'm not seeing the /target topic in the list. So currently I'm not able to publish targets. Any suggestions?

Logs ros2 topic list

    /device_container_node/transition_event
    /motor_left/joint_states
    /motor_left/nmt_state
    /motor_left/rpdo
    /motor_left/tpdo
    /motor_right/joint_states
    /motor_right/nmt_state
    /motor_right/rpdo
    /motor_right/tpdo
    /parameter_events
    /rosout

Bus.yml

    options:
      dcf_path: "@BUS_CONFIG_PATH@"

    master:
      node_id: 10
      driver: "ros2_canopen::MasterDriver"
      package: "canopen_master_driver"
      sync_period: 1000

    defaults:
      dcf: "PD4-CB59M024035-E-08.eds"
      driver: "ros2_canopen::Cia402Driver"
      package: "canopen_402_driver"
      polling: true
      period: 10
      diagnostics:
        enable: false
      scale_pos_to_dev : 1.0
      scale_vel_to_dev : 1.0
      scale_pos_from_dev : 1.0
      scale_vel_from_dev : 1.0
      heartbeat_producer: 2000
      sdo: # SDO executed during config
        - {index: 0x6081, sub_index: 0, value: 1} # Set velocity
        - {index: 0x6083, sub_index: 0, value: 600} # Set acceleration
        - {index: 0x6083, sub_index: 0, value: 600} # Set deceleration
        - {index: 0x6085, sub_index: 0, value: 6000} # Set quickstop deceleration
        - {index: 0x6098, sub_index: 0, value: 35} # Set default homing mode to 35
        - {index: 0x60C2, sub_index: 1, value: 50} # Set interpolation time for cyclic modes to 50 ms
        - {index: 0x60C2, sub_index: 2, value: -3} # Set base 10-3s

    nodes:
      motor_left:
        node_id: 1

      motor_right:
        node_id: 2

launch file

    import os
    import sys

    sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))  # noqa
    sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", "..", "launch"))  # noqa

    import launch
    from launch.actions import IncludeLaunchDescription
    from launch.launch_description_sources import PythonLaunchDescriptionSource
    from ament_index_python import get_package_share_directory
    from launch import LaunchDescription

    def generate_launch_description():
        ld = LaunchDescription()

        device_container = IncludeLaunchDescription(
            PythonLaunchDescriptionSource(
                [
                    os.path.join(get_package_share_directory("canopen_core"), "launch"),
                    "/canopen.launch.py",
                ]
            ),
            launch_arguments={
                "master_config": os.path.join(
                    get_package_share_directory("nanotec_pd4_can"),
                    "config",
                    "double-pd4",
                    "master.dcf",
                ),
                "master_bin": os.path.join(
                    get_package_share_directory("nanotec_pd4_can"),
                    "config",
                    "double-pd4",
                    "master.bin",
                ),
                "bus_config": os.path.join(
                    get_package_share_directory("nanotec_pd4_can"),
                    "config",
                    "double-pd4",
                    "bus.yml",
                ),
                "can_interface_name": "can0",
            }.items(),
        )

        ld.add_action(device_container)

        return ld

Setup:

• OS: Ubuntu 22.04
• ROS-Distro: Humble
• Motor: PD4-CB59M024035-E-08

[lucasmluza]

The "/target" is a service, just like the "/init", and "/halt". You can check if it is available by running:

ros2 service list

If so, the "/target" may be set, for example, by:

ros2 service call /motor_left/target canopen_interfaces/srv/COTargetDouble "{ target: 10.0 }"

[VerlooyNick]

Indeed, that works. But for integration into a robot system working with the service does not seem the right way. Image I have a joystick creating a velocity command which I want to apply to the motor. I’d assume I could publish to a certain topic to have a more real time behaviour instead of working with services.

[hellantos]

This is where you would use the ros2_control interface that provides you with all kind of streaming options. Though I understand that the setup is a bit more difficult, we have a short but probably not optimal example here: https://ros-industrial.github.io/ros2_canopen/manual/rolling/user-guide/how-to-create-a-robot-system.html

[jclinton830]

This is where you would use the ros2_control interface that provides you with all kind of streaming options. Though I understand that the setup is a bit more difficult, we have a short but probably not optimal example here: https://ros-industrial.github.io/ros2_canopen/manual/rolling/user-guide/how-to-create-a-robot-system.html

@ipa-cmh Have you tested this robot system approach on real hardware?

[VerlooyNick]

Right now I'm working with the proxy driver and writing my own Cia402 application layer. Is the documentation for the Cia402 driver correct? This states that the /target is a subscriber but it only appears as a service?

[hellantos]

@ipa-cmh Have you tested this robot system approach on real hardware?

@jclinton830 we have the driver running on pilz prbt robot (6 axis robot arm). Apart from that we have just created a solution for a customer on Maxon hardware, this has pointed out some problems with the sdo timeouts.

Sorry we are currently a bit slow with work on the stack, but we are currently quite bound into other projects. Should get better in November though. I will prepare a workshop on the robot system part for ROS I Workshop in Singapore end of November.. That will hopefully add some of the necessary documentation.