Design of Pneumatic Origami Muscle Actuators (POMAs) for A Soft Robotic Hand Orthosis for Grasping Assistance

Soft robotics technologies have recently been used in various wearable applications for their high conformability to complex geometries of different parts of a human body. One of most widely explored application areas is rehabilitation by motion and force augmentation. Particularly, assistance of hand motions for stroke patients, using glove-type wearable devices, is actively investigated these days. The glove-type devices can provide additional force for flexion and extension of finger motions, helping grasping tasks of the wearers who do not have enough strength or control of their hand and finger muscles. Many of the glove-type devices are actuated by soft pneumatic muscles composed of elastomer air chambers. In spite of the advantages of flexibility and conformability to three-dimensional body shapes, they require relatively high air pressure enough to overcome the stiffness of the host material as well as complex multi-step molding and casting processes for fabrication. In this paper, we propose pneumatic origami muscle actuators (POMAs) that not only can be fabricated by a simple laser machining process but also consume relatively small pneumatic energy for actuation. Furthermore, the lightweight origami structure of the proposed POMAs provides a high force-to-weight ratio. This paper describes the design and the fabrication of a POMA followed by the characterization results. It also presents a wearable robotic device as an application, which can be used for assisting hand motions for stroke patients, made of multiple POMAs.