Single-Leg Forward Hopping via Nonlinear Modes

Abstract

Implementing dynamic legged locomotion entails stabilizing oscillatory behaviors in complex mechanical systems. Whenever possible, locomotion algorithms should also exploit the improved capabilities of elastic elements added to the structure to improve efficiency and robustness. This work aims to shed some light on implementing generic dynamic locomotion by stabilizing nonlinear modes. The nonlinear modal analysis extends the linear modal theory to nonlinear systems and thus characterizes the oscillations that a robot can execute as autonomous evolutions. We execute forward hopping motions with a single segmented elastic leg as the first step towards generic modal locomotion. We propose a locomotion algorithm that exploits the modes of an extension of the SLIP model. We develop this strategy to generalize to other robotic systems, and we extensively validate it with experiments on an elastically actuated segmented leg.

Energy, Passivity, and Morphological Capacities

“…Moreover, even if the body of a system cannot perform a task by itself, it may reduce the control effort. Examples of this phenomenon are the bipedal robots designed in [33], and the locomotion approach proposed in [34].…”

PAWS: A Synergy-Based Robotic Quadruped Leveraging Passivity for Robustness and Behavioural Diversity

“…To overcome this, increasingly we are seeing encouraging results from approaches that exploit bioinspiration and, more specifically, physical, compliance-driven embodied intelligence (20) for robotic locomotion (21)(22)(23)(24). Recent examples include the excitation of natural jumping locomotion in a cat-inspired robotic leg in (25), the dragonfly-larvae-inspired compliant robot that can emulate a synchronized dual-catapult system for ballistic movements in (26), a quadruped with a felinelike multi-joint spine for high-speed running (27), and Birdbot, an ostrich inspired robot relying upon a clutch-based mechanism yielding efficient locomotion (28).…”