Pinto: A latched spring actuated robot for jumping and perching

TL;DR

Pinto is a lightweight, latched spring-actuated robot capable of jumping onto trees and perching, inspired by squirrel locomotion, with innovative energy storage and switching mechanisms for efficient arboreal movement.

Contribution

The paper introduces a novel latched series-elastic actuator and a switching leg mechanism enabling energetic jumps and perching in a small robot, advancing arboreal robotics.

Findings

Latched elastic energy storage increases jump energy.

Switching between elastic modes enables versatile jumping and control.

Robot successfully performs tree-jumping and high-speed perching.

Abstract

Arboreal environments challenge current robots but are deftly traversed by many familiar animal locomotors such as squirrels. We present a small, 450 g robot "Pinto" developed for tree-jumping, a behavior seen in squirrels but rarely in legged robots: jumping from the ground onto a vertical tree trunk. We develop a powerful and lightweight latched series-elastic actuator using a twisted string and carbon fiber springs. We consider the effects of scaling down conventional quadrupeds and experimentally show how storing energy in a parallel-elastic fashion using a latch increases jump energy compared to series-elastic or springless strategies. By switching between series and parallel-elastic modes with our latched 5-bar leg mechanism, Pinto executes energetic jumps as well as maintains continuous control during shorter bounding motions. We also develop sprung 2-DoF arms equipped with spined grippers to grasp tree bark for high-speed perching following a jump.