Modeling and Analysis of Oblique-Chamber and Symmetric Oblique-Chamber Pneu-Net Soft Actuators

Oblique-chamber pneu-net soft actuators (OC-PNSAs) exhibit helical deformation upon inflation. The symmetric oblique-chamber pneu-net soft actuator (SOC-PNSA) consists of two symmetric OC-PNSAs. By adjusting the pressures in the two chambers, the deformation shape can be controlled, enabling it to grasp objects of varying shapes. In this letter, we first establish a deformation model for OC-PNSAs. We demonstrate that the OC-PNSA bends around the inclined wall upon inflation, thereby revealing the mechanism of its helical deformation. Furthermore, we demonstrate that the helical bending angle of the OC-PNSA is equal to the bending angle of the PNSA with the same dimensions. Therefore, the existing PNSA bending model can be applied to OC-PNSAs. Additionally, considering the coupling effects of the symmetric oblique chambers, we develop a deformation model for SOC-PNSAs based on the OC-PNSA model and the principle of equivalent effects. Both experiments and simulations validate the theoretical model's accuracy in predicting actuator deformation. The proposed model is valuable for optimizing the design and control of helical actuators, aiding their application in grasping objects of diverse shapes.