This package is an implementation of robotic in-hand manipulation technique that can be applied to pick an object too large to grasp in a prehensile manner, by taking advantage of its contact interactions with a curved, passive end-effector, and two flat support surfaces. First, the object is tilted up while being held between the end-effector and the supports. Then, the end-effector is tucked into the gap underneath the object, which is formed by tilting, in order to obtain a grasp against gravity. We demonstrate successful picking of objects of various size and geometry using our technique through a set of experiments performed with a custom-made robotic device and a conventional robot arm. Our experiment results show that object picking can be performed reliably with our method using simple hardware and control, and when possible, with appropriate fixture design.
Related Paper
Y. Song, A. Nazir, D. Lau, and Y. Liu, "Picking by Tilting: In-Hand Manipulation for Object Picking using Effector with Curved Form," submitted to 2023 International Conference on Robotics and Automation (ICRA).
- Each of the two joints connected to the ground is actuated by a HT8108-J6 DC motor (rated torque: 6.9 Nm at 24 volts, according to the manufacturer1) through a built-in planetary gear train. (http://www.haitaijd.cn/)
- The axes of the motors are horizontally offset to realize the desired manipulation behavior of the palm. The palm is 3D printed and covered with a high-friction rubber material. Its proximal end features a curved, ellipsical surface to facilitate tilting by rolling.
To execute the picking operation:
cd dexterous_picking/robot_arm/scripts/5 bar mechanism
python Control by keys.py
To get plots of the result data:
cd dexterous_picking/robot_arm/scripts/5 bar mechanism
python Plot by Python.py
To execute the picking operation on a large steel box
cd dexterous_picking/robot_arm/scripts
python large_steel_box.py