open_manipulator_x

In this repo, you can find the integration of OpenManipulatorX with ros2_control. Based on the code provided by Robotis, updated to work with the Humble distribution of ROS 2. You can use it by including open_manipulator_x_macro in the URDF of your robot, for example:

<xacro:include
    filename="$(find open_manipulator_x_description)/urdf/open_manipulator_x_macro.urdf.xacro"
    ns="manipulator" />
  <xacro:manipulator.open_manipulator_x parent_link="cover_link"
    xyz="-0.1 0.0 0.0"
    rpy="0.0 0.0 0.0"
    use_sim="False"
    collision_enabled="True"
    usb_port="/dev/ttyUSB0"
    baud_rate="1000000"
    joint1_limit_min="-2.356"
    joint1_limit_max="5.934" />

Parameters description:

• parent_link link to which manipulator will be attached (with transform specified by xyz and rpy parameters)
• tf_prefix - optional parameter that can be used to add some prefix to all links of the manipulator (can be omitted, as in the example)
• use_sim - whether simulation ros2_control plugin should be included instead of real hardware one (currently only Gazebo is supported).
• collision_enabled - due to lack of dedicated collision meshes of open_manipulator_x, visual ones are also used for collisions. This can result in a drop in simulation performance, you can opt to disable collisions in this case.
• usb_port in case of using hardware, name of USB port where manipulator is connected (e.g. /dev/ttyUSB0).
• baud_rate in case of using hardware, a baud rate of communication with servos.
• joint1_limit_min and joint1_limit_max - with these parameters you can adjust limits on the first joint of the manipulator - it is constrained by the cable connecting the first and second servo, and it can differ depending on how this cable was connected and the length of it.

Additionally, you have to add an appropriate controller, an example is provided in the open_manipulator_x_hardware/config directory.

For an exact usage example of the manipulator please check out rosbot_xl_manipulation_ros.

Usage

Before activating torque, the current position of the manipulator is read, then it is set as a goal position - the manipulator stays in the position that it was activated.

Turning off torque

One useful thing that can be a little tricky is turning off the torque of the manipulator's joints. To do it, you have to manually set the hardware controller to an inactive state:

ros2 service call /controller_manager/set_hardware_component_state \
  controller_manager_msgs/srv/SetHardwareComponentState \
  "{name: 'manipulator', target_state: {id: 0, label: 'inactive'}}"

To activate it again use the same service, but change the label to active.