ASTRE: Prototyping Technique for Modular Soft Robots With Variable Stiffness

Soft robots are advantageous for human interaction owing to their adaptability and safe interactivity. However, research on soft robots is challenging because of the complex fabrication process of elastomeric materials with multiple channels. In this study, we introduce a prototyping technique for the fabrication-friendly soft robots using pneumatic artificial muscle(PAMs) and modular 3D printed reinforcement. We presented three primitive deformation structures: bending, twisting, and contraction. Moreover, we propose a novel variable stiffness technique that alters PAMs contraction and radial expansion behavior into locking, malleable, and rotational brake features. We explore both the parallel and series arrangement of the reinforcement module and propose new types of mixing configurations and scaling techniques. We quantitatively verified the force scaling technique on different types of features. We demonstrate the feasibility of this prototyping technique through six application examples and conclude with a discussion of the limitations and possible future improvements.