Analysis of Soft Mechanisms Using a Homogenized Strain Induced Model

Modeling soft robots that constitute the deliberate arrangement of fundamental soft actuators oriented in spatial architectures can be computationally intensive. This may restrict the designer’s ability to quickly ideate and evaluate potential solutions. This paper presents a homogenized strain induced model (HSIM) to capture the static response characteristics of a Fiber Reinforced Pneumatic Artificial Muscle (FRPAM). The HSIM approximates a FRPAM as nonlinear beam with stepped cross section whose geometric parameters are tuned by either experimental data or high-fidelity finite element analysis. The efficacy of the tuned model is demonstrated in a variety of applications in simulation and more importantly from experiments carried out on two prototypes made entirely from FRPAMs arranged in a bio-inspired pennate architecture. The model is implemented in a commercial finite element package (ABAQUS) and primarily serves as an ideation tool, where designers can sketch different architectures composed of FRPAMs and analyze their force-deformation characteristics. Furthermore, such a model can also be useful in integrating with topology optimization routines to synthesize optimal spatial arrangement of actuators.