An origami-based anthropomorphic rotary robotic Arm

Abstract

Soft rotary arms were developed to enhance the manipulators’ dexterity and versatility, enabling them to better orient objects in space, adjust grasping angles, and perform precise manipulations. However, these soft arms struggle to achieve both large rotation angles and torques that are comparable to those of human forearms. Here, this study demonstrates an anthropomorphic rotary robotic arm whose maximum rotation angle and maximum output torque are comparable to those of the human forearm. The robotic arm contains two origami actuators, whose interaction allows the arm to produce a specific rotation angle and torque. This robotic arm exploits a soft-rigid hybrid mechanism, combining both soft, compliant origami actuators and rigid structural components to leverage their complementary strengths. This design of the arm enables it to transition from compliant to strong as needed for dynamic tasks; for example, the robotic arm can not only gently rotate a key with three rectangular protrusions through a narrow gap, but also apply high torque to loosen the quick-release lever on a bicycle's wheel. By bridging the gap between soft adaptability and rigid precision, our study provides soft rotary arms with a critical step toward safer, more versatile, and human-compatible robotic systems.