Design and validation of a programmable dual-tunnel soft pneumatic origami actuator with a large maximum shrinkage rate for reciprocating motion

Abstract

Soft actuators have attracted significant research in various domains owing to their flexible motion characteristics. However, the applications of soft actuators are constrained by their low force-to-weight ratio and maximum shrinkage rate, which is the ratio of the maximum stroke to the extreme length of the actuator, considerably augmenting the driving energy and occupied area. This paper presents a novel dual-tunnel soft pneumatic origami actuator capable of providing a large maximum shrinkage rate for reciprocating motion. The inner tunnel is constructed by the origami mechanism chamber, and the outer tunnel is formed by the origami mechanism in conjunction with the outer soft skin. A programmable design method for the proposed actuator is presented, based on its geometric parameter model and stiffness model. A kinematics model is developed to analyze the motion behavior and characteristics of the actuator's reciprocating motion. The prototype is fabricated using lightweight materials, such as oriented polypropylene and hard cardboard, on which tensile and load experiments are conducted. The results verify the motion characteristics of the soft actuator and the accuracy of the model. Compared to other linear actuators, the soft origami actuator is lightweight (weighing 5 g), has a large maximum shrinkage rate (61 %) and boasts a force-to-weight ratio of 600. The design demonstrates the extensive application potential of soft actuators with the origami mechanism.