EZGripper

A ROS2 package that serves as a driver to the EZGripper module designed by SAKE Robotics. If you are not using ROS, use https://github.com/SAKErobotics/SAKErobotics

Tutorial

Installation

---

• Install the python EZGripper library. Use the python3 version from the ubuntu 20.04 branch.

• Install gazebo_ros2_control to enable Gazebo to mimic the EZGripper joints:

  git clone https://github.com/leander-dsouza/gazebo_ros2_control -b foxy
  

• Install all the remaining dependencies using rosdep, at the root of your ROS workspace:

  rosdep install --from-paths src --ignore-src -r -y
  

• Clone the ROS2 Driver at your src folder:

  git clone --branch=foxy-devel https://github.com/blackcoffeerobotics/EZGripper_ros2.git
  

• Build your workspace and source it:

  colcon build --symlink-install
  source install/setup.bash
  

• For testing hardware through a joystick, connect your USB joystick to the system and execute:

  ros2 launch ezgripper_driver joy.launch.py
  

Simulation testing

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• Launch the gripper module in RViz :

  ros2 launch ezgripper_description display.launch.py
  

• Similarly to launch in Gazebo:

  ros2 launch ezgripper_gazebo gazebo.launch.py
  

• To actuate the gripper into its respective open/close configurations in Gazebo:

  # Open Gripper
  ros2 run ezgripper_control open_gripper
  
  # Close Gripper
  ros2 run ezgripper_control close_gripper
  

• Result of actuation:

  

MoveIt!

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• To launch the ezgripper in Gazebo and RViz for control:

  ros2 launch ezgripper_single_mount_moveit_config demo_gazebo.launch.py
  

• To control the ezgripper hardware through MoveIt!:

  ros2 launch ezgripper_single_mount_moveit_config ezgripper_single_mount_moveit_planning_execution.launch.py
  

Additional Configurations

• Setup parameters in joy.yaml file

  • port -
            serial device (like /dev/ttyUSB0) or tcp endpoint (like 192.168.0.200:5000) to use.

  • baudrate -
            baud rate of the serial device, not used for tcp.

  • no_of_grippers -
            number of grippers to control.

  • Depending upon the number of grippers, gripper profiles can be created as shown:

    gripper_1:
    	action_name: gripper_cmd
    	servo_ids: [1]
    	module_type: dual_gen2_single_mount
    	robot_ns: main
    

    action_name -
            name of the action to be used.
    servo_ids -
            list of servo ids to control. (several ids if several grippers are to be used as one group). For example [9] and [10,11] for two grippers.
    By default, SAKE Robotics delivers its grippers with address 1 for Duals and 1 and 2 for Quads and 57kbps.
    robot_ns -
            namespace of the robot.

• Example launch files to support various EZGripper configurations.

  ros2 launch ezgripper_driver joy.launch.py
  # joy.launch is configured for a single servo gripper (dual) and the USB interface
  
  ros2 launch ezgripper_driver joy2.launch.py
  # joy2.launch is configured for two independent servos (quad independent) and the USB interface
  
  ros2 launch ezgripper_driver joy2sync.launch.py
  # joy2sync.launch controls two servos as if it were a single servo (quad dependent) and the USB interface
  
  ros2 launch ezgripper_driver joy_tcp.launch.py
  # joy_tcp.launch controls a single servo via TCP instead of USB
  

Action API

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• The driver provides an implementation of the SimpleActionServer, that takes in control_msgs/GripperCommand actions.
  
• A sample client (scripts/ezgripper_joy_action_client.py) is included that provides joystick control using the action API.

URDF Models

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Access the URDF models for additional information.

TroubleShooting

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Serial connection issues:

• The following message indicates you have a new version of serial library that causes issues.

  Error message: 'Serial' object has no attribute 'setParity'  ---
  

  Do the following command to load an older serial library.

  sudo apt-get install python3-serial==2.0.0
  

• This indicates the user does not have privileges to use the /dev/ttyUSBx:

  Error message: permission denied (get accurate error message).
  

  The solution is to add the <user> to the dialout group. After executing the following command, reboot.

  sudo adduser <user> dialout
  reboot