An Experimental Platform for Understanding Scaling of Latch-Mediated Spring Actuation

Latch-mediated spring actuation (LaMSA) systems use elastic elements to produce extremely strong strikes, high jumps, and other fast movements that outperform direct motor actuation at small size scales. The size-scaling of LaMSA performance has been mathematically modeled, but not physically modeled. We present development and experimental validation of a LaMSA mechanism for understanding scaling of latch-mediated spring actuation. The mechanism consists of a symmetric five-bar linkage with an elastic element running across it and was designed to use commercially available components and common fabrication techniques. We created two versions of the mechanism isometrically scaled by almost an order of magnitude in size. Using high speed videography to measure and track the unloading kinematics, we found the mechanism's maximum velocity and acceleration. The kinematics follow the expected scaling predicted by mathematical modeling, but only after accounting for unexpected differences in stored elastic energy and overall mass. These initial tests demonstrate the mechanism's utility as an experimental platform for understanding scaling of LaMSA systems. We also present design features that enable future investigations of payload mass and different elastic element scaling regimes.