Tuning impulsive mechanisms to their environment*

Organisms like fleas and froghoppers achieve fast repeatable motions due to the presence of highly tuned impulsive mechanisms; a motor slowly loads a spring, and this stored energy is quickly released by a latch. In this work, we explore how the latch and spring parameters are tuned to their environments to maximize performance. An analytical model is constructed to include both impulsive system parameters (e.g., mass, spring, latch) as well as the compliance and inertia of the environment. Simulations are then performed across the design space to understand the tuning relationship between the latch, spring and substrate (environment) parameters. These results are validated experimentally using an 8-gram robot for which latch and spring parameters can be changed. This robot is then tested on multiple compliant substrates. Results demonstrate that the latch and spring parameters can be tuned to their environment to maximize take-off velocity. Certain combinations of latch/spring/environment parameters result in recovery of energy from the compliant substrate thereby resulting in higher performance, and ultimately efficient, fast, and repeatable motions.