A Novel and Practicable Approach for Determining the Beam Parameters of Soft Pneumatic Multi-Chamber Bending Actuators

Abstract

The design of many pneumatic soft actuators is based on multiple chambers in parallel alignment. The Cosserat beam theory is an established technique for modeling this kind of actuator, where existing approaches mainly differ in the parameters being required for simulation. The modeling approach presented in this study particularly aims at finding the beam parameters necessary for a simulation even with limited experimental methods. Importantly, it provides a straightforward relationship between the bending stiffness, the extensional stiffness and the axial stretch of the actuator. If the actuator to be modeled has an elementary design, axial measurements are sufficient to identify the parameters to perform three-dimensional simulations, which is of interest to adopters with limited testing equipment. The experimentally parameterized model of such an actuator of elementary design shows high accuracy. Both without load and with a weight of 1N applied to the tip, the mean error of the tip position in vertical orientation is less than 3.4% for a constant extensional stiffness and less than 2.7% for a pressure-dependent extensional stiffness. Further reduction of the error could be achieved by more refined identification techniques that decompose the complex interrelationship of pressurization, forces and material stiffness.