Variable Ankle Stiffness Improves Balance Control: Experiments on a Bipedal Exoskeleton

This paper proposes a real-time balance control technique that can be implemented to bipedal robots (exoskeletons, humanoids) whose ankle joints are powered via variable physical stiffness actuators. To achieve active balancing, an abstracted biped model, torsional spring-loaded flywheel, is utilize...

Full description

Saved in:
Bibliographic Details
Published in:IEEE/ASME transactions on mechatronics 2016-02, Vol.21 (1), p.79-87
Main Authors: Ugurlu, Barkan, Doppmann, Corinne, Hamaya, Masashi, Forni, Paolo, Teramae, Tatsuya, Noda, Tomoyuki, Morimoto, Jun
Format: Article
Language:English
Subjects:
Actuators
balance control
Constants
exoskeleton
Exoskeletons
Joints
Knee
Legged locomotion
Mathematical model
Mathematical models
Mechatronics
Reduction
Robots
Stiffness
Strategy
zero moment point
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:This paper proposes a real-time balance control technique that can be implemented to bipedal robots (exoskeletons, humanoids) whose ankle joints are powered via variable physical stiffness actuators. To achieve active balancing, an abstracted biped model, torsional spring-loaded flywheel, is utilized to capture approximated angular momentum and physical stiffness, which are of importance in postural balancing. In particular, this model enables us to describe the mathematical relation between zero moment point (ZMP) and physical stiffness. The exploitation of variable physical stiffness leads to the following contributions: 1) Variable physical stiffness property is embodied in a legged robot control task, for the first time in the literature to the authors' knowledge. 2) Through experimental studies conducted with our bipedal exoskeleton, the advantages of variable physical stiffness strategy are demonstrated with respect to the optimal constant stiffness strategy. The results indicate that the variable stiffness strategy provides more favorable results in terms of external disturbance dissipation, mechanical power reduction, and ZMP/center of mass position regulation.
ISSN:1083-4435
1941-014X
DOI:10.1109/TMECH.2015.2448932