Quadrupedal Spine Control Strategies: Exploring Correlations Between System Dynamic Responses and Human Perspectives

TL;DR

This study investigates different spine control strategies in quadrupedal robots to enhance gait naturalness and human perception, finding that optimized and foot-tracking strategies improve perceived naturalness despite no energy efficiency gains.

Contribution

It introduces and evaluates novel spine trajectory strategies for quadrupedal robots, linking system dynamics with human perception of gait naturalness.

Findings

Optimized time-varying and foot-tracking strategies are perceived as more natural.

No energy efficiency improvements over fixed spine baseline.

Some strategies improve footfall consistency at higher speeds.

Abstract

Unlike their biological cousins, the majority of existing quadrupedal robots are constructed with rigid chassis. This results in motion that is either beetle-like or distinctly robotic, lacking the natural fluidity characteristic of mammalian movements. Existing literature on quadrupedal robots with spinal configurations primarily focuses on energy efficiency and does not consider the effects in human-robot interaction scenarios. Our contributions include an initial investigation into various trajectory generation strategies for a quadrupedal robot with a four degree of freedom spine, and an analysis on the effect that such methods have on human perception of gait naturalness compared to a fixed spine baseline. The strategies were evaluated using videos of walking, trotting and turning simulations. Among the four different strategies developed, the optimised time varying and the foot-tracking strategies were perceived to be more natural than the baseline in a randomised trial with 50 participants. Although none of the strategies demonstrated any energy efficiency improvements over the no-spine baseline, some showed greater footfall consistency at higher speeds. Given the greater likeability drawn from the more natural locomotion patterns, this type of robot displays potential for applications in social robot scenarios such as elderly care, where energy efficiency is not a primary concern.