Pleated Film-Based Soft Twisting Actuator

Soft robotics and actuators are becoming increasingly popular with diverse applications; their compliant structures and smooth deformations, which give rise to its softness, offer inherent safety to humans. This paper introduces the design of a twisting soft actuator based on pleated films that is inspired by the design of composite structures and that is capable of very large twisting angles. It has a simple design, it is easy to manufacture, low-cost, can be made from a wide range of inexpensive materials, can produce large twisting deformations (> 360°) and large torque (> 0.7 Nm). The proposed actuator design consists of a flat structure composed of two inextensible films that are bonded to form a pouch that expands like a balloon when pressurized. This pouch has anti-symmetrically arranged pleats on the surface of both films that cause the actuator to undergo a twisting along with the expansion of the volume. A parametric study of the actuator including the angle of the pleats, the number of pleats, the width of the actuator, the pleat width and the distance between pleats was conducted to determine the effect of each parameter on the twisting angle and the torque produced.