Using elastic instabilities to overcoming nature's actuation limitations: dynamics of ultrafast motion in biological and bio-inspired systems

Generating ultra-fast movements is a multifaceted design challenge, as systems are often constrained by the inherent trade-offs in actuator force and velocity as well as the mechanical response of their structures and materials. At the intersection of structural dynamics, biomechanics, and physiology, this talk explores how the fastest organisms on Earth overcome these limitations to achieve extraordinary accelerations using elastic instabilities.

Small organisms, such as mantis shrimps, trap-jaw ants, fleas, and click beetles, have evolved specialized power-amplification systems that enable accelerations exceeding 10^6 m/s²—orders of magnitude greater than engineered systems and far surpassing even well-known exemplars of speed like the cheetah (cheetahs can accelerate up to ∼15 m/s²). These acceleration specialists leverage intricate latches and springs mechanisms to bypass the force-speed limitations of their muscles, amplifying power output to achieve ultra-fast motion. We utilize a multi-scale analytical and experimental dynamics framework to investigate the physical principles underlying these extreme motions. Using click beetles as a case study, we examine their unique power-amplified clicking mechanism, which enables legless jumps through a thoracic hinge that integrates latches and distributed springs. By analyzing the hinge's morphology, kinematics, and dynamics, we identify the elastic and damping forces driving rapid energy release and the strategies for transmitting power while mitigating structural damage. This framework not only deepens our understanding of biological systems but also offers actionable design principles for enhancing the performance of bio-inspired systems, such as insect-scale robots and ultra-fast actuators, by mimicking nature’s solutions to actuation limitations.