Coupled Transverse-Longitudinal Deformation Analysis of Soft Bending Actuators Using Cosserat Rod Theory

In this research, an approach called Cosserat Rod theory was initially proposed to model the coupled longitudinal-transverse deformation of the beam. Additionally, considering the anisotropic behavior of the soft fiber-reinforced actuator, distinct effective stiffness values were selected for the longitudinal and transverse directions. Diverging from the convention of many other models, this approach did not rely on the assumption of constant curvature. Subsequently, the obtained results were subjected to validation across four different pressure levels. The validation results indicated RMS errors ranging from 0.03 to 0.32 for the Cosserat rod model and ranging from 0.34 to 2.51 for the constant curvature model, corresponding to pressure levels of 0.3 and 0.9 bar, respectively. As a result, it is evident that coupling the transverse and longitudinal behavior of the actuator not only improved the accuracy of the longitudinal deformation in the theoretical model compared to the experimental results but also enhanced the accuracy of its transverse deformation concerning the experimental results.