Design of a foldable origami-inspired 6-DoF Stewart mechanism

Parallel mechanisms function as positioning platforms for various applications. However, they are required to be customized, compact, and scalable for medium or small-scale applications. Origami-inspired design and layer-by-layer fabrication methods are used to provide these needed features. Though, as the degree-of-freedom (DoF) increases, the complexity of the design increases. This work presents a novel, foldable, miniature Stewart parallel mechanism with 6 DoF, which has a complex structure even for conventional methods using rigid parts. The developed mechanism is monolithic, having designed unique flexible joints. When folded, it has a 16 cm diameter circular footprint that works effectively in a 20×20×20 mm³ cubic workspace. Inside this volume, the X and Y-axis rotational ranges are ±10° and the Z-axis rotational range is ±7.5. The fabrication of the mechanism consists of an iterative process where only necessary cutting and laminating steps are used. In addition, the manual folding and bonding steps are eliminated, which are challenges for shrinking the size of these parallel mechanisms. We used the conventional Stewart mechanism kinematics model and conducted experiments to analyze the motion-tracking performance of the mechanism. We applied various planar circular and simultaneous rotational and translational motion trajectories and analyzed the results by comparing them with the given trajectories.