A variable stiffness composite mixed with pneumatic muscle fibers and elastomer

Abstract

Pneumatic muscle fibers (PMFs) are a type of pneumatic artificial muscles (PAMs) with millimeter-scale diameter, which show great power to be a soft actuator under injecting the compressed fluid into its bladder. In this paper, the pressurized PMF was considered and investigated as a spring system due to the active contraction capability. The stiffness and variable stiffness characteristics of pressurized PMFs were theoretically investigated by utilizing a non-linear quasi-static model. Experiments were conducted to validate the theoretical model, and the experimental results have good agreement with the model predictions. A variable stiffness composite which was embedded with PMFs into the soft elastomer was presented and experimented to explore the potential adaptive shape-changing behaviors. The composite presented in this paper consists of 16 PMFs with the linear array distribution and two rectangular plates were used to support the PMFs. By taking advantage of the variable stiffness characteristics of pressurized PMFs, the presented composite shows the capability of varying stiffness partly and the shapes of the presented composite can change flexibly.