Amplifying the Kinematics of Origami Mechanisms With Spring Joints

TL;DR

This paper introduces the spring joint, a novel origami mechanism that amplifies kinematic output and offers enhanced control by coupling multiple folds, with potential applications and a modular alternative for practical use.

Contribution

The paper presents the spring joint, a new mechanism that significantly amplifies and controls origami kinematics, along with a modular version to address layer buildup issues.

Findings

Amplifies kinematic output by up to ten times

Provides additional parameters for control of fold behavior

Demonstrates effectiveness as a replacement in various origami structures

Abstract

Due to its rigid foldability and predictable kinematics, the reverse fold is the fundamental mechanism behind some of the most well known origami kinematic structures, including the Miura Ori, Yoshimura, and waterbomb patterns. However, the reverse fold only has one parameter to control its behavior: the starting fold angle. In this paper I introduce an alternative to the traditional reverse fold, based on the spring into action pattern, called the spring joint. This novel rigidly foldable mechanism is able to couple multiple reverse folds into a compact space to amplify the kinematic output of a traditional reverse fold by up to ten times, and to add one parameter for each reverse fold, giving more programmatic control of origami structures. Methods of parameterizing both the starting angle, the path of travel, and the axis of motion are also introduced. Unfortunately, this versatility comes at the cost of a large buildup of layers, making the spring joint impractical for thick origami mechanisms. To solve this problem, I also introduce a modular alternative to the spring joint that has no additional layers, with the same kinematic properties. Both of these mechanisms are tested as replacements for the reverse fold in both traditional and custom origami structures.