A Simulation-Based Toolbox to Expedite the Digital Design of Bellow Soft Pneumatic Actuators

Task-oriented applications of soft pneumatic actuators (SPAs) are growing, as digital design and rapid prototyping allow the actuator to be customised. The bellow SPA is promising for current soft material 3D printing due to small material stretch during actuation, yet the complex geometry causes challenges in physical modelling and design. This article provides the users with an open-source toolbox of simulation for a standardised bellow soft pneumatic actuator that can be 3D printed to expedite the design process. Based on MATLAB and COMSOL Multiphysics, the toolbox allows users to customise design features, automatically generate the CAD and then simulate the actuators' performance. It provides two methods to analyse the design: 1) a theoretical modelling method to quickly generate the actuator's workspace with interactive results, 2) a finite element method to evaluate in detail the actuator's deformation and force performance as well as the mechanical properties. The modelling is introduced and validated by comparing the experimental results of 3D printed bellow actuator prototypes with simulation results for angular deflection and blocked force. The maximum root-mean-square error for the theoretical modelling of deformation, finite element method of deformation and force are $9.00^{\circ}, 7.40^{\circ}$ and 1.66 g, respectively.