Low-Profile Folding Mechanism for Multi-DoF Feedback Control

Abstract

Soft structures gain their adaptability from a high number of distributed degrees of freedom (DoF). Integrating reconfigurable robotic systems into these soft structures enables efficient transmission of forces and torques, supporting a wide range of tasks. However, implementing actuation, sensing, and transmission components remains challenging, particularly in optimizing their spatial distribution to achieve effective control over the target structure. In this study, we present an embeddable pneumatic system featuring ultra-thin actuators, with integrable sensors and modular transmissions. The system’s ultra-thin profile enables seamless and space-efficient integration onto various surfaces, while its modular design enables flexible reconfiguration to suit different mechanical and control needs. The rolling diaphragm mechanism reduces friction and stress on the joints which are more prone to occur in flat structures. The proposed diaphragm has an aspect ratio of approximately 10 (15 mm ×1.4 mm cross-section) and achieves a stroke length up to five times its thickness, extendable through modular connection. An optical sensor module is also introduced to provide precise, low-profile feedback without affecting the mechanical characteristics or flatness of the overall system. We demonstrate the control of folding sequence and angle through feedback control, using compactly embedded components within an origami-inspired surface. This approach leverages the geometric principles of folding to enable complex and reconfigurable structures. The proposed integrable actuator, transmission, and sensor module provides a scalable and customizable foundation for developing large-scale robotic systems with intricate geometries and distributed control, supporting seamless deployment and adaptability.