Quadrupedal spine control strategies: exploring correlations between system dynamic responses and human perspectives

2025-03-25

Adv. Robotics

AI Summary

Conventional quadrupedal robots employ rigid chassis, resulting in gaits lacking the natural fluidity of mammalian locomotion; prior spinal actuation research prioritized energy efficiency while neglecting human subjective perception of motion naturalness in human–robot interaction. Method: This work systematically investigates, for the first time, the impact of a biomimetic four-degree-of-freedom spinal motion strategy on human-rated naturalness, introducing two novel control approaches—time-varying optimization and end-effector foot tracking—to generate walking, trotting, and turning motions in dynamic simulation. A randomized controlled experiment (N=50) assessed subjective naturalness scores, complemented by quantitative analysis of plantar contact consistency. Results: Both strategies significantly improved naturalness ratings (p<0.01) and enhanced foot-landing consistency at higher speeds. Although no reduction in energy consumption was observed, the approach demonstrates strong potential for socially assistive robotics applications, such as elderly care and companionship.

Technology Category

• Intelligent Robots: Human-Robot Interaction
• Cognitive Modeling & Cognitive Systems: Simulating Human Behavior
• Humans and AI: Interaction Techniques and Devices

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• User Modeling, Personalization and Recommendation: User modeling and simulation for interactive and conversational systems
• Search and Retrieval-Augmented AI: Assisted, interactive, and conversational search

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.

Problem

• Lack of natural fluidity in rigid quadrupedal robot movements
• Ignoring human perception in spinal robot gait design
• No energy efficiency gain from current spine strategies

Innovation

• Four DOF spine trajectory generation strategies
• Human perception analysis of gait naturalness
• Foot-tracking strategy for natural locomotion