Soft robotic hands provide better safety and adaptability than rigid robotic hands. Furthermore, a multijointed structure that imitates the movement of a human hand represents significant progress in realizing its anthropomorphism. In this study, we present a multijointed pneumatic soft anthropomorphic hand that is capable of expressing letters through sign language and grasping different objects using three grasping modes, namely thumb grasping, precision grasping, and power grasping. This novel soft hand is composed of multijointed soft fingers, a thumb, thenar, and 3D-printed palm. Tests were performed to characterize the displacement track and force performance of the fingers, thumb, and thenar, which was made by mold casting silicone rubber. In addition, a dedicated pneumatic control system was designed and built to enable the soft hand to automatically perform the tasks set by specific programs. This new multijointed hand with a flexible thenar represents significant progress in the development of anthropomorphic bionic hands, offering the benefits of fast response, low cost, as well as ease of fabrication, assembly, and replacement.
Keywords: anthropomorphic hand; firm grasp; flexibility; gesture; multijointed; soft thenar actuator.