One-Finger Manipulation of 3D Objects by Planning Start-to-Push Points and Pushing Forces

In this letter, we propose a one-finger nonprehensile manipulation strategy for repositioning and reorienting a 3D object in a frictional environment. The proposed manipulation strategy consists of the periodic searching and pushing modes of the robotic finger. In the searching mode, the finger starts from its initial configuration and searches for the start-to-push point on the object surface. The manipulability distribution can be quickly evaluated by defining three factors reflecting the continuous pushing distance, the contact force transmissibility, and the pushing demand of the object. In the pushing mode, the pushing force is planned to drive the object toward the desired pose. When the current pushing is less efficient, the finger rewinds to its initial configuration and restarts the searching mode. Both simulation and experimental results show that different 3D objects on a frictional table can be driven to the desired pose using a torque-driven robotic finger when the finger's base frame is appropriately selected.