Passive arm stiffness affects payload stability in quadruped walking
Gait-Dependent Effects on Quadruped Locomotion for Load-Carrying using Passive Mechanism
Robotics
Summary
Carrying loads on four-legged robots using simple, spring-like arms is lighter than using powered arms, but the way these arms move depends on the walking style. The authors studied how adjusting the arm’s spring and damping settings changes carrying stability during different walking patterns. They found that with a slow and stable walk (crawl gait), making the arms less damped causes more swinging and can make the robot less stable. The study provides maps that help choose arm settings for different walks and payloads to keep the robot balanced.
What this means in practice
- •For robotics engineers: Design passive arm settings for four-legged robots to improve load stability during different walking gaits.
- •For automated warehouse operators: Optimize quadruped robot load carrying by selecting mechanical settings that reduce balance risk on flat floors.
Tested on simulated data.
Authors
Giovanni B. Dessy, Claudio Semini, Victor Barasuol
Abstract
Passive mechanical interfaces offer a lightweight alternative to actuated manipulators for quadruped payload carrying, but their impedance directly couples the payload dynamics with the locomotion pattern. This paper analyzes how passive-arm stiffness-damping selection affects payload-carrying locomotion under different gait and payload conditions. We compare damped and underdamped passive-arm impedance configurations in simulation during flat-ground locomotion. For crawl gaits, where the support polygon remains well defined, the results show that underdamped impedance increases passive-joint oscillations and can reduce the ZMP margin with respect to the support polygon. Trot is retained as a dynamic excitation case for the passive arm, but it is not used for direct ZMP-margin stability comparison. The results are summarized in gait-payload-stiffness-damping maps, where ZMP-margin reduction is evaluated for crawl gaits and trot is retained only as a passive-arm excitation case.