The concept of "dexterous manipulation" refers to a the ability of a robotic hand to reorient a grasped object or to finely adjust it in the hand. The ability to reorient a grasped object means the robot can use the best technique to grasp an object, without worrying about how to use it or place it. This ability has obvious usefulness in making robotic manipulation faster and more capable. However, in the past, dexterous manipulation has been associated with a particular hand's complexity and dexterity. We propose the approach of "extrinisic dexterity", wherein external resources such as gravity, contact forces, or inertia from the arm movements are exploited to manipulate objects. For example, we consider throwing and catching an object, pushing the object against an external surface, or letting the object roll or swing in the hand under the influence of gravity. Examples of extrinisic dexterity have been developed by hand and can be seen in the video above. I am focusing on the regrasp called "drooping" wherein the object is loosely held in the hand so that it can rotate but not translate. Then, we can use gravity and inertial forces to rotate the object in the hand.



A General Framework for Open-loop Pivoting
Anne Holladay, Robert Paolini, Matthew Mason. Proceedings of the IEEE International Conference on Robotics and Automation. Seattle, Washington, 2015. 

Advisors: Matthew mason

Extrinsic Regrasping

CMU RI MLab