An Origami-Inspired Negative Pressure Folding Actuator Coupling Hardness with Softness

Abstract

Soft actuators have a high potential for the creative design of flexible robots and safe human–robot interaction. So far, significant progress has been made in soft actuators’ flexibility, deformation amplitude, and variable stiffness. However, there are still deficiencies in output force and force retention. This paper presents a new negative pressure-driven folding flexible actuator inspired by origami. First, we establish a theoretical model to predict such an actuator’s output force and displacement under given pressures. Next, five actuators are fabricated using three different materials and evaluated on a test platform. The test results reveal that one actuator generates a maximum pull force of 1125.9 N and the maximum push force of 818.2 N, and another outputs a full force reaching 600 times its weight. Finally, demonstrative experiments are conducted extensively, including stretching, contracting, clamping, single-arm power assistance, and underwater movement. They show our actuators’ performance and feature coupling hardness with softness, e.g., large force output, strong force retention, two-way working, and even muscle-like explosive strength gaining. The existing soft actuators desire these valuable properties.

Evolution from Telescoping to Bending: An Origami-Inspired Flexible Bending Actuator

“…Inspired by origami, we have previously designed a flexible telescopic actuator [41], and its schematic diagram is shown in Figure 1. Our telescopic actuator has excellent properties of large force output, bi-directional working, and good force retention.…”

“…Remarkably, origami exhibiting outstanding structural and topological properties can be a paradigm for people to design various soft robots [7,8,27,[38][39][40]. Inspired by origami, we have previously designed a telescopic actuator with excellent properties of large force output, bi-directional working, and good force retention [41]. Soft bending actuators expect them as well.…”