Origami crawlers: exploring a single origami vertex for complex path navigation

The ancient art of origami, traditionally used to transform simple sheets into intricate objects, also holds potential for diverse engineering applications, such as shape morphing and robotics. In this study, we demonstrate that one of the most basic origami structures (i.e., a rigid, foldable degree-four vertex) can be engineered to create a crawler capable of navigating complex paths using only a single input. Through a combination of experimental studies and modeling, we show that modifying the geometry of a degree four vertex enables sheets to move either in a straight line or turn. Furthermore, we illustrate how leveraging the nonlinearities in folding allows the design of crawlers that can switch between moving straight and turning. Remarkably, these crawling modes can be controlled by adjusting the range of the actuation folding angle. Our study opens avenues for simple machines that can follow intricate trajectories with minimal actuation.