Postural Virtual Fixtures for Ergonomic Physical Interactions with Supernumerary Robotic Bodies

TL;DR

This paper introduces a control framework for supernumerary robotic bodies that provides ergonomic feedback and posture correction to improve user comfort and safety during physical interactions.

Contribution

It presents a novel virtual fixture control method combined with ergonomic posture assessment to promote proper posture and coordination in human-robot interactions.

Findings

Effective in discouraging non-ergonomic postures

Improves coordination between operator and robot

Enhances long-term ergonomic habits

Abstract

Conjoined collaborative robots, functioning as supernumerary robotic bodies (SRBs), can enhance human load tolerance abilities. However, in tasks involving physical interaction with humans, users may still adopt awkward, non-ergonomic postures, which can lead to discomfort or injury over time. In this paper, we propose a novel control framework that provides kinesthetic feedback to SRB users when a non-ergonomic posture is detected, offering resistance to discourage such behaviors. This approach aims to foster long-term learning of ergonomic habits and promote proper posture during physical interactions. To achieve this, a virtual fixture method is developed, integrated with a continuous, online ergonomic posture assessment framework. Additionally, to improve coordination between the operator and the SRB, which consists of a robotic arm mounted on a floating base, the position of the floating base is adjusted as needed. Experimental results demonstrate the functionality and efficacy of the ergonomics-driven control framework, including two user studies involving practical loco-manipulation tasks with 14 subjects, comparing the proposed framework with a baseline control framework that does not account for human ergonomics.