Robotic Contact Juggling
Contact juggling is a form of object manipulation where the juggler controls the motion of an object, often a crystal ball, as it rolls on the juggler’s arms, hands, torso, or even shaved head. The manipulation is typically nonprehensile (no form- or force-closure grasp) and dynamic, i.e., momentum plays a crucial role. An example is shown below.
This is a variation of a contact juggling skill called “the butterfly.” The object (typically a ball) is initially at rest on the palm, and the goal state is rest on the back of the hand. The hand is accelerated to cause the object to roll up and over the fingers to the other side of the hand. This research addresses modeling, motion planning, and feedback control to solve dynamic rolling manipulation tasks.
Woodruff, J. Zachary, and Kevin M. Lynch. “Robotic Contact Juggling.” IEEE Transactions on Robotics, 2023. paper | TRO| code.
Woodruff, J. Zachary, Shufeng Ren, and Kevin M. Lynch. “Motion planning and feedback control of rolling bodies.” IEEE Access, vol. 8, 2020. pdf.
Woodruff, J. Zachary, and Kevin M. Lynch. “Second-order contact kinematics between three-dimensional rigid bodies.” Journal of Applied Mechanics vol. 86 issue 8, 2019. pdf.
Hybrid Manipulation
Traditionally, robotic manipulation tasks have been performed by firmly grasping an object and then moving it to a new location. Operations like this are widely used in the manufacturing industry, but there are many everyday manipulation tasks such as pushing, rolling, hitting, and throwing that do not necessarily involve a grasp. Planning for these motions is a difficult problem that has not been well explored. I have developed contact models between objects and manipulators to estimate how to achieve desired object motions when objects are not constrained from slipping and rolling on a manipulator. I have tested these experimentally with a planar robot moving parallel to the surface of an air hockey table to simulate a reduced-gravity environment. This project involves object marker tracking, motor control, motion planning, and developing safety systems.
Woodruff, J. Zachary, and Kevin M. Lynch. “Planning and control for dynamic, nonprehensile, and hybrid manipulation tasks.” Robotics and Automation (ICRA), 2017 IEEE International Conference on. IEEE, 2017. pdf.
In-Hand Sliding Manipulation
This work focuses on planning manipulation tasks that involve an object sliding in a manipulator’s grasp.
Shi, Jian, J. Zachary Woodruff, Paul Umbanhowar, and Kevin M. Lynch. “Dynamic in-hand sliding manipulation.” IEEE Transactions on Robotics, vol. 33, issue 4, pp. 778-795, 2017. pdf.
Shi, Jian, J. Zachary Woodruff, and Kevin M. Lynch. “Dynamic in-hand sliding manipulation.” Intelligent Robots and Systems (IROS), 2015 IEEE/RSJ International Conference on. IEEE, 2015. pdf.