Flexiv ROS 2

For ROS 2 users to easily work with RDK, the APIs of RDK are wrapped into ROS packages in flexiv_ros2. Key functionalities like real-time joint torque and position control are supported, and the integration with ros2_control framework and MoveIt! 2 is also implemented.

References

Flexiv RDK main webpage contains important information like RDK user manual and network setup.

Compatibility

Release Status

ROS 2 Distro	Foxy	Humble
Branch	foxy	humble
Release Status

Getting Started

This project was developed for ROS 2 Foxy (Ubuntu 20.04) and Humble (Ubuntu 22.04). Other versions of Ubuntu and ROS 2 may work, but are not officially supported.

1. Install ROS 2 Humble via Debian Packages

2. Install colcon and additional ROS packages:

   sudo apt install -y \
   python3-colcon-common-extensions \
   python3-rosdep2 \
   libeigen3-dev \
   ros-humble-xacro \
   ros-humble-tinyxml2-vendor \
   ros-humble-ros2-control \
   ros-humble-realtime-tools \
   ros-humble-control-toolbox \
   ros-humble-moveit \
   ros-humble-ros2-controllers \
   ros-humble-test-msgs \
   ros-humble-joint-state-publisher \
   ros-humble-joint-state-publisher-gui \
   ros-humble-robot-state-publisher \
   ros-humble-rviz2
   

1. Setup workspace:

   mkdir -p ~/flexiv_ros2_ws/src
   cd ~/flexiv_ros2_ws/src
   git clone https://github.com/flexivrobotics/flexiv_ros2.git
   cd flexiv_ros2/
   git submodule update --init --recursive
   

1. Install dependencies:

   cd ~/flexiv_ros2_ws
   rosdep update
   rosdep install --from-paths src --ignore-src --rosdistro humble -r -y
   

[!NOTE] Skip step 5 and 6 if you have compile and install flexiv_rdk.

1. Choose a directory for installing flexiv_rdk library and all its dependencies. For example, a new folder named rdk_install under the home directory: ~/rdk_install. Compile and install to the installation directory:

   cd ~/flexiv_ros2_ws/src/flexiv_ros2/flexiv_hardware/rdk/thirdparty
   bash build_and_install_dependencies.sh ~/rdk_install
   

1. Configure and install flexiv_rdk:

   cd ~/flexiv_ros2_ws/src/flexiv_ros2/flexiv_hardware/rdk
   mkdir build && cd build
   cmake .. -DCMAKE_INSTALL_PREFIX=~/rdk_install
   cmake --build . --target install --config Release
   

1. Build and source the workspace:

   cd ~/flexiv_ros2_ws
   source /opt/ros/humble/setup.bash
   colcon build --symlink-install --cmake-args -DCMAKE_PREFIX_PATH=~/rdk_install
   source install/setup.bash
   

[!NOTE] Remember to source the setup file and the workspace whenever a new terminal is opened:

source /opt/ros/humble/setup.bash
source ~/flexiv_ros2_ws/install/setup.bash

Usage

[!NOTE] The instruction below is only a quick reference, see the Flexiv ROS 2 Documentation for more information.

The prerequisites of using ROS 2 with Flexiv Rizon robot are enable RDK on the robot server and establish connection between the workstation PC and the robot.

The main launch file to start the robot driver is the rizon.launch.py - it loads and starts the robot hardware, joint states broadcaster, Flexiv robot states broadcasters, and robot controller and opens RViZ. The arguments for the launch file are as follows:

• robot_sn (required) - Serial number of the robot to connect to. Remove any space, for example: Rizon4s-123456
• rizon_type (default: rizon4) - type of the Flexiv Rizon robot. (rizon4, rizon4s, rizon10 or rizon10s)
• load_gripper (default: false) - loads the Flexiv Grav gripper as the end-effector of the robot and the gripper control node.
• use_fake_hardware (default: false) - starts FakeSystem instead of real hardware. This is a simple simulation that mimics joint command to their states.
• start_rviz (deafult: true) - starts RViz automatically with the launch file.
• fake_sensor_commands (default: false) - enables fake command interfaces for sensors used for simulations. Used only if use_fake_hardware parameter is true.
• robot_controller (default: rizon_arm_controller) - robot controller to start. Available controllers: forward_position_controller, rizon_arm_controller, joint_impedance_controller.

(Details about other launch files can be found in flexiv_bringup)

Example Commands

1. Start robot, or fake hardware:

   • Test with real robot:

     ros2 launch flexiv_bringup rizon.launch.py robot_sn:=[robot_sn] rizon_type:=rizon4
     

• Test with fake hardware (ros2_control capability):

     ros2 launch flexiv_bringup rizon.launch.py robot_sn:=Rizon4-123456 use_fake_hardware:=true
     

[!TIP] To test whether the connection between ROS and the robot is established, you could disable the starting of RViz first by setting the start_rviz launch argument to false.

1. Publish commands to controllers

   • To send the goal position to the controller by using the node from flexiv_test_nodes, start the following command in a new terminal:

     ros2 launch flexiv_bringup test_joint_trajectory_controller.launch.py robot_sn:=[robot_sn]
     

 The joint position goals can be changed in `flexiv_bringup/config/joint_trajectory_position_publisher.yaml`    - To test another controller, define it using the `robot_controller` launch argument, for example the `joint_impedance_controller`:

     ros2 launch flexiv_bringup rizon.launch.py robot_sn:=[robot_sn] robot_controller:=joint_impedance_controller
     

 Open a new terminal and run the launch file:

     ros2 launch flexiv_bringup sine_sweep_impedance.launch.py robot_sn:=[robot_sn]
     

 The robot should run a sine-sweep motion with joint impedance control.

[!NOTE] The command starts the robot in the joint torque mode. In this mode, gravity and friction are compensated only for the robot without any attached objects (e.g. the gripper, camera).

[!NOTE] Joint impedance control is not supported in fake/simulated hardware.

Using MoveIt

You can also run the MoveIt example and use the MotionPlanning plugin in RViZ to start planning:

ros2 launch flexiv_bringup rizon_moveit.launch.py robot_sn:=[robot_sn]

Test with fake hardware:

ros2 launch flexiv_bringup rizon_moveit.launch.py robot_sn:=Rizon4-123456 use_fake_hardware:=true

Robot States

The robot driver (rizon.launch.py) publishes the following feedback states to the respective ROS topics:

• /${robot_sn}/flexiv_robot_states: Flexiv robot states including the joint- and Cartesian-space robot states. [flexiv_msgs/msg/RobotStates.msg]
• /joint_states: Measured joint states of the robot: joint position, velocity and torque. [sensor_msgs/JointState.msg]
• /${robot_sn}/tcp_pose: Measured TCP pose expressed in world frame $^{0}T_{TCP}$ in position $[m]$ and quaternion. [geometry_msgs/PoseStamped.msg]
• /${robot_sn}/external_wrench_in_tcp: Estimated external wrench applied on TCP and expressed in TCP frame $^{TCP}F_{ext}$ in force $[N]$ and torque $[Nm]$. [geometry_msgs/WrenchStamped.msg]
• /${robot_sn}/external_wrench_in_world: Estimated external wrench applied on TCP and expressed in world frame $^{0}F_{ext}$ in force $[N]$ and torque $[Nm]$. [geometry_msgs/WrenchStamped.msg]

GPIO

All digital inputs on the robot control box can be accessed via the ROS topic /{robot_sn}/gpio_inputs, which publishes the current state of all the 18 (16 on control box + 2 inside the wrist connector) digital input ports (True: port high, false: port low).

The digital output ports on the control box can be set by publishing to the topic /{robot_sn}/gpio_outputs. For example:

ros2 topic pub /Rizon4_123456/gpio_outputs flexiv_msgs/msg/GPIOStates "{states: [{pin: 0, state: true}, {pin: 2, state: true}]}"

Gripper Control

The gripper control is implemented in the flexiv_gripper package to interface with the gripper that is connected to the robot.

Start the flexiv_gripper_node with the following launch file, the default gripper is Flexiv Grav (Flexiv-GN01):

ros2 launch flexiv_gripper flexiv_gripper.launch.py robot_sn:=[robot_sn] gripper_name:=Flexiv-GN01

Or, you can also start the gripper control with the robot driver if the gripper is Flexiv Grav:

ros2 launch flexiv_bringup rizon.launch.py robot_sn:=[robot_sn] load_gripper:=true

Gripper Actions

In a new terminal, send the gripper action move goal to open or close the gripper:

# Closing the gripper
ros2 action send_goal /flexiv_gripper_node/move flexiv_msgs/action/Move "{width: 0.01, velocity: 0.1, max_force: 20}"
# Opening the gripper
ros2 action send_goal /flexiv_gripper_node/move flexiv_msgs/action/Move "{width: 0.09, velocity: 0.1, max_force: 20}"

The grasp action enables the gripper to grasp with direct force control, but it requires the mounted gripper to support direct force control. Send a grasp command to the gripper:

ros2 action send_goal /flexiv_gripper_node/grasp flexiv_msgs/action/Grasp "{force: 0}"

To stop the gripper, send a stop service call:

ros2 service call /flexiv_gripper_node/stop std_srvs/srv/Trigger {}