Design Paradigms Based on Spring Agonists for Underactuated Robot Hands: Concepts and Application

TL;DR

This paper explores a novel design paradigm for underactuated robot hands using springs as agonists and tendons as antagonists, formalizing the approach in a design matrix and demonstrating its practical benefits through prototypes.

Contribution

It introduces a formal design matrix for spring agonist-based underactuated hands and demonstrates how combining tendons and springs on a single motor shaft enables versatile behaviors.

Findings

Design matrix formalizes spring agonist approach

Combining tendons on one motor shaft enables multiple behaviors

Prototype demonstrates practical implementation

Abstract

In this paper, we focus on a rarely used paradigm in the design of underactuated robot hands: the use of springs as agonists and tendons as antagonists. We formalize this approach in a design matrix also considering its interplay with the underactuation method used (one tendon for multiple joints vs. multiple tendons on one motor shaft). We then show how different cells in this design matrix can be combined in order to facilitate the implementation of desired postural synergies with a single motor. Furthermore, we show that when agonist and antagonist tendons are combined on the same motor shaft, the resulting spring force cancellation can be leveraged to produce multiple desirable behaviors, which we demonstrate in a physical prototype.