Date of Award
Master of Science (MS)
This research investigates the effects of using origami folding techniques to develop a nonlinear jumping mechanism with optimized dynamic performance. A previous theoretical investigation has shown the benefits of using a nonlinear spring element compared to a linear spring for improving the dynamic performance of a jumper. This study sets out to experimentally verify the effectiveness of utilizing nonlinear stiffness to achieve optimized jumping performance. The Tachi-Miura Polyhedron (TMP) origami structure is used as the nonlinear energy-storage element connecting two end-point masses. The TMP bellow exhibits a “strain-softening” nonlinear force-displacement behavior resulting in an increased energy storage compared to a linear spring. The geometric parameters of the structure are optimized to improve air-time and maximum jumping height. An additional TMP structure was designed to exhibit a close-to-linear force-displacement response to serve as the representative linear spring element. A critical challenge in this study is to minimize the hysteresis and energy loss of TMP during its compression stage before jumping. To this end, plastically annealed lamina emergent origami (PALEO) concept is used to modify the creases of the structure in order to reduce hysteresis during the compression cycle. PALEO works by increasing the folding limit before plastic deformation occurs, thus improving the energy retention of the structure. Steel shim stock are secured to the facets of the TMP structure to serve as end-point masses, and the air-time and jumping height of both structures are measured and compared. The nonlinear TMP structure achieves roughly 9% improvement in air-time and a 12% improvement in jumping height when compared to the linear TMP structure. These results validate the theoretical benefits of utilizing nonlinear spring elements in jumping mechanisms and can lead to improved performance in dynamic systems which rely on springs as a method of energy storage and can lead to emergence of a new generation of more efficient jumping mechanisms with optimized performance in the future.
Allison, Samuel Reese, "Exploiting the Nonlinear Stiffness of Origami Folding to Enhance Robotic Jumping Performance" (2020). All Theses. 3373.