Lift-off dynamics in a simple jumping robot

TL;DR

This study investigates the lift-off dynamics of a simple actuated mass-spring robot, revealing optimal jumping modes above and below resonance, driven by non-resonant transient dynamics.

Contribution

It introduces a systematic analysis of jump performance relative to actuator frequency and phase, identifying two distinct optimal jumping modes and explaining their dynamics.

Findings

Optimal jumps occur above and below the resonant frequency.

Two jumping modes: squat and stutter jumps.

Non-resonant transient dynamics drive optimal lift-off.

Abstract

We study vertical jumping in a simple robot comprising an actuated mass-spring arrangement. The actuator frequency and phase are systematically varied to find optimal performance. Optimal jumps occur above and below (but not at) the robot's resonant frequency $f_0$. Two distinct jumping modes emerge: a simple jump which is optimal above $f_0$ is achievable with a squat maneuver, and a peculiar stutter jump which is optimal below $f_0$ is generated with a counter-movement. A simple dynamical model reveals how optimal lift-off results from non-resonant transient dynamics.