Designing Underactuated Graspers with Dynamically Variable Geometry Using Potential Energy Map Based Analysis

TL;DR

This paper extends the energy map method for in-hand manipulation to include friction, enabling the design of underactuated grippers with variable geometry for improved grasping versatility.

Contribution

It analytically incorporates friction into energy maps for two-link underactuated fingers and evaluates key gripper parameters through extensive simulations.

Findings

Friction can be included in energy maps for underactuated fingers.

Variable palm width is essential for handling different part sizes.

Adjustable transmission ratio improves grasping capabilities.

Abstract

This paper introduces an extension to the energy map method for in-hand manipulation. Energy maps are used to predict how a part will evolve in the grasp given a specific actuation input to the gripper. Previous approaches assumed frictionless contacts, but we show analytically that friction can be included in the energy maps when using two-link underactuated fingers by understanding the evolution of the part-finger contact. These friction-based energy maps were used to evaluate the importance of various tendon-pulley gripper parameters across nearly 6 million simulated grasping scenarios. Specifically, a variable palm width is needed to manipulate parts of varying scales, and a variable transmission ratio, or the ratio of the distal to the proximal pulley radii, is needed to draw parts into a cage or to maintain a tip prehension grasp.