Two Degree-of-Freedom Vibratory Transport in a Grasp
This work addresses the problem of precise in-hand manipulation for robotic grippers, offering an incremental improvement in control over part movement.
This paper demonstrates two degree-of-freedom in-hand manipulation of grasped parts using asymmetric vibrations. By controlling two vibratory waveform parameters, the sticking and slipping accelerations, the authors achieved bidirectional translation and rotation of various parts within a parallel jaw gripper.
In this paper, we use asymmetric vibrations to demonstrate two degree-of-freedom (DoF) in-hand manipulation of grasped parts. The asymmetric vibrations are achieved through closed-loop position control of a moving surface, which applies a periodic stick-slip waveform to the part to be manipulated. We show analytically how two vibratory waveform parameters, the sticking acceleration and the slipping acceleration, affect average part velocity when moving against gravity. The theoretical trends are then validated using an experimental setup where the squeeze force is controlled and part motion is recorded by a high-resolution encoder. We also develop a 2-DoF vibratory surface capable of translation in one direction and rotation about the surface normal. Using two of these 2-DoF surfaces in a parallel jaw gripper configuration, we bidirectionally translate and rotate a variety of grasped parts, as well as demonstrate that the same waveform trends for translation also persist for in-plane rotation.