No 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.

Soft actuators have great potential in human–machine interaction and soft robotics innovation. Origami exhibiting outstanding structural and topological properties can be a paradigm for people to design various soft robots. Inspired by origami, we have previously designed a telescopic actuator with excellent performance, mainly large force output, and two-way working. Although significant advances have been made in soft bending actuators, their further study and applications are limited due to small force output in a monotonous work style. In this paper, we design a series of novel bending actuators that inherit our prior telescopic actuator’s excellent characteristics to diversify soft actuators’ motion forms. Several actuators of different sizes are fabricated using three different materials and evaluated on a designed test platform. The test results show that actuators of different sizes using different materials perform differently. Namely, the maximum tip force produced by an actuator reaches 9.6 N, and the maximum bending angle is achieved by another one up to 138°. Finally, extensive demonstrations and tests include wriggling, gripping, and bidirectional motion in the water. They show our flexible bending actuators’ distinguishing characteristics of large output force and two-way working.