Utilizing Sacrificial Molding for Embedding Motion Controlling Endostructures in Soft Pneumatic Actuators

The field of soft robotics has evolved as a domain for developing light, compliant and safe actuators. However, one of the challenges in the field is the lack of repeatable fabrication techniques as well as customizability that restricts the application of soft robots. We present a fabrication technique using sacrificial molding to fabricate pneumatic channels that are repeatable and less prone to variability. This technique enables the monolithic fabrication of actuators which eliminates conventional failure modes such as delamination. We then use embedded endostructures manufactured using Fused Deposition Modelling (FDM) 3D printers to customize the behavior of bending actuator by altering local mechanical characteristics. Finite element analysis (FEA) was used as a tool to tune the choice of materials and the geometry of the 3D printed layers based on the required application. We analyze the effect of the mechanical properties of the endostructures on actuator behavior and its utility in improving customizability. We analyzed the behavior of actuators with a variety of endostructures using visual markers. As predicted by the FEA and Euler-Bernoulli beam theory, the behavior of the actuators was seen to be influenced by the mechanical properties of the endostucture. Thus, we present a new methodology for tuning the mechanical properties of Soft Pneumatic Actuators (SPAs), which is simple and efficient to predict as well as easy to execute.