Evaluation of an acceleration-based assistive strategy to control a back-support exoskeleton for manual material handling

Maria Lazzaroni,Michiel P. de Looze,Stefano Toxiri,Ali Tabasi,Darwin G. Caldwell,Jaap H. van Dieën,Idsart Kingma,Jesús Ortiz,Elena De Momi,Wietse van Dijk

doi:10.1017/wtc.2020.8

Maria Lazzaroni, Michiel P. de Looze + Show 8 more

Open Access

https://doi.org/10.1017/wtc.2020.8

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Abstract

Abstract To reduce the incidence of occupational musculoskeletal disorders, back-support exoskeletons are being introduced to assist manual material handling activities. Using a device of this type, this study investigates the effects of a new control strategy that uses the angular acceleration of the user’s trunk to assist during lifting tasks. To validate this new strategy, its effectiveness was experimentally evaluated relative to the condition without the exoskeleton as well as against existing strategies for comparison. Using the exoskeleton during lifting tasks reduced the peak compression force on the L5S1 disc by up to 16%, with all the control strategies. Substantial differences between the control strategies in the reductions of compression force, lumbar moment and back muscle activation were not observed. However, the new control strategy reduced the movement speed less with respect to the existing strategies. Thanks to improved timing in the assistance in relation to the typical dynamics of the target task, the hindrance to typical movements appeared reduced, thereby promoting intuitiveness and comfort.

Highlights

Musculoskeletal disorders (MSDs) are the most frequent occupational disease in many industrialized countries (Punnett and Wegman, 2004; Bevan, 2012; Parent-Thirion et al, 2016), with significant socioeconomic impact on individuals and health care systems (Davies et al, 2003; Woolf and Pfleger, 2003; Hoy, 2014)
The averages of the peak values across all subjects for the total L5S1 moment, the net L5S1 moment generated by the subject, the averaged IL and LL activity, the compression force on L5S1, the trunk inclination angle, and the trunk angular velocity were tested using three-way ANOVA
A main effect of the execution speed was found for all the variables

Summary

Introduction

Musculoskeletal disorders (MSDs) are the most frequent occupational disease in many industrialized countries (Punnett and Wegman, 2004; Bevan, 2012; Parent-Thirion et al, 2016), with significant socioeconomic impact on individuals and health care systems (Davies et al, 2003; Woolf and Pfleger, 2003; Hoy, 2014). Common to many industrial sectors, manual material handling (MMH) tasks increase the risk of developing MSDs associated with the back (Zurada, 2012). Biomechanics of Back-Related MSDs Back-related MSDs are associated with mechanical overloading and compression on the spine (Kumar, 2001; Coenen et al, 2014). E9-2 Maria Lazzaroni et al. Due to the difficulty in quantifying the reduction of MSDs, an easier approach involves the assessment of the risk factors identified as increasing MSDs incidence during MMH. The extensor moment about the lumbar joint indicates the response of the musculoskeletal system to the external load applied and largely determines spine compression (Van Dieën and Kingma, 2005). Peak and cumulative extensor moments have been identified among the factors that increase the risk of developing MSDs during lifting tasks (Marras et al, 1995; Norman et al, 1998))

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