Gripper Control using Dynamixel 12A and OpenRB-150

Repository containing code to control Dynamixel motor(s) (12A - Tested) with OpenRB-150 Controller. The software is designed in a way to prevent occurence of the overcurrent in the Dynamixels and enable slippage detection.

Getting started

1. Download Arduino IDE (do not use Ubuntu software manager!).
2. Open the IDE, go to File->Preferences and add the below line to the Additional Boards Manager URLs:

   https://raw.githubusercontent.com/ROBOTIS-GIT/OpenRB-150/master/package_openrb_index.json
   

3. Download libraries for Arduino IDE (Tools->Manage Libraries):
   • Arduino SAMD Board Manager
   • OpenRB-150
   • Dynamixel2Arduino
   • CircularBuffer
   • Arduino_JSON
4. Open file openrb_150_controller.ino in the openrb_150_controller directory, compile it and upload on the microcontroller.

Setting up the Dynamixel

• Please follow the guide here.
• Setup video can be found here.
• For setting the baudrate here.
• Connection diagram:
• A Molex-JST convertible cable is required to connect the Dynamixel to the OpenRB-150 board.
• For configuring the motors using Dynamixed Wizard 2.0, you can use the same setup and connect the USB cable to the computer.

Note: Please make sure to set the Jumper on the OpenRB-150 board to 12V as highlighted in the above image. Otherwise, the motor will not work.

Dynamixel 12A motor configuration

• ID's: 1, 2
• DXL_PROTOCOL_VERSION: 1.0
• Baudrate: 9600
• Operating mode: Position control
• Inpt voltage: 12V

Usage

• Connect the USB cable to the microcontroller and the computer.
• Select the Board (OpenRB-150) and Port (e.g. /dev/ttyACM0) in the Arduino IDE (Tools->Board, Tools->Port)
• Open the serial monitor in the Arduino IDE (Tools->Serial Monitor) and set the baudrate to 9600.
• You can see the feedback from the microcontroller in the serial monitor like:

  gripper_command: 0.00 curr_pos: 448 new_pos: 450 change_state: 0
  {"state":"GRIPPER_OPEN","parsing_error":0,"last_command":0,"left_gripper_pos":129,"right_gripper_pos":166,"diff_encoders":-37}
  

• In the Message input window, you can send commands to control the gripper position:
  • {"command": 0.0} - open the gripper
  • {"command": 1.0} - close the gripper
  • You can also send the command to set the gripper position in the range [0.0, 1.0] (0.0 - open, 1.0 - close): {"command": 0.5}
  • If you want to further open the gripper, you can send command in the range [-1.5, 1.0]: {"command": -1.0}

ROS Usage

• For the ROS interface, please check the script at mas_industrial_robotics