Origami-Inspired 3-DoF Robotic Joint Design With Pneumatic Actuators

Abstract

Soft pneumatic joints, as the core components of soft robotic manipulators, often face a trade-off between multiple degrees of freedom (DoF) mobility and load capacity. Inspired by the Yoshimura origami pattern, this paper presents a rigid–soft hybrid pneumatic joint. Through spatially ordered placement of rigid and compliant elements and co-optimization of crease topology, the joint realizes three DoF—two rotational and one translational (2R+1 T). We also introduce a fabrication method for a dual-mode soft pneumatic actuator (SPA): thin rigid plates, linked by mechanical hinges, are embedded along the chamber's inner wall to mitigate stress concentrations at membrane weld seams, raising the pressure tolerance above 0.6 MPa and enabling both positive and negative pressure operation. We develop a kinematic model and an analytical quasi-static model that map pneumatic pressure to output torque and angular displacement, supporting control and design optimization. Experiments show that a 1.5 kg single-joint prototype lifts a 240 kg load under positive gauge pressure and generates a 59 kg pulling load under negative gauge pressure; circular-trajectory tracking validates position control. A multi-joint manipulator assembled from the proposed joints carries 13.6 kg at a 0.5 m horizontal moment arm. These results demonstrate that the proposed hybrid architecture simultaneously achieves multi-DoF mobility and high load capacity.