A Passivity-based Concurrent Whole-Body Control (cWBC) of Persistently Interacting Human-Exoskeleton Systems

TL;DR

This paper introduces a passivity-based concurrent whole-body control method for human-exoskeleton systems that enhances force amplification and safety by ensuring system passivity and energy dissipation.

Contribution

It proposes a novel passivity-based control framework for tightly coupled human-exoskeleton systems that improves force amplification and safety during power augmentation tasks.

Findings

The coupled system is demonstrated to be passive with energy always dissipating.

The control method effectively cancels gravity effects and maintains balance.

The approach enhances human operator capabilities while reducing injury risk.

Abstract

This paper presents a concurrent whole-body control (cWBC) for human-exoskeleton systems that are tightly coupled at a Cartesian level (e.g., feet, hands, torso). The exoskeleton generates joint torques that i) cancel the effects of gravity on the coupled system, ii) perform a primary task (e.g., maintaining the balance of the system), and iii) exploit the kinematic redundancy of the system to amplify the forces exerted by the human operator. The coupled dynamic system is demonstrated to be passive, as its overall energy always goes dissipated until a minimum is reached. The proposed method is designed specifically to control exoskeletons for power augmentation worn by healthy operators in applications such as manufacturing, as it allows to increase the worker's capabilities, therefore reducing the risk of injuries.