The use of revolute joints in robotics is widespread, but their performance can still be improved. The goal of this research is to enhance robot joints by utilizing origami structures, which offer numerous benefits such as space efficiency, and reduced production time and costs (due to flat-foldability). In this work, we investigated various origami crease patterns, categorizing and analyzing them based on their movements. Inspired by the earwig wing and Miura-ori unit cell pattern, we designed and fabricated Four-vertex and Self-lock origami models, and analyzed their rotational motions, moments, and actuator pressure relations. The origami designs are simulated with different central angle plates, and constructed using cutting and binding and 3D-printing methods. We developed rotational manipulators and modeled transitional and modular manipulators as proof of concept.

The results of the study demonstrate that origami joints with central angles closer to $90^\circ$ degrees show larger rotational motion changes compared to traditional revolute joints (equivalent to a simple fold) with the same actuator. They save actuator pressure and are deployable in different sizes and weights. Moreover, the position of the central angles in the Self-lock origami affects the direction of movements. The manipulators are used with different central angle plates to illustrate the rotational and transitional movements in different directions. The proposed Self-lock origami joints can generate bi-directional movement and increase moment in specific rotational phases. The joint is also modular and can be connected to similar or different joints to produce complex movements for various applications.