Effectiveness of Soft versus Rigid Back-Support Exoskeletons during a Lifting Task

Abstract

This study investigated the influence of passive back-support exoskeletons (EXOBK) design, trunk sagittal inclination (TSI), and gender on the effectiveness of an exoskeleton to limit erector spinae muscle (ES) activation during a sagittal lifting/lowering task. Twenty-nine volunteers performed an experimental dynamic task with two exoskeletons (two different designs: soft (SUIT) and rigid (SKEL)), and without equipment (FREE). The ES activity was analyzed for eight parts of TSI, each corresponding to 25% of the range of motion (lifting: P1 to P4; lowering: P5 to P8). The impact of EXOBK on ES activity depended on the interaction between exoskeleton design and TSI. With SKEL, ES muscle activity significantly increased for P8 (+36.8%) and tended to decrease for P3 (−7.2%, p = 0.06), compared to FREE. SUIT resulted in lower ES muscle activity for P2 (−9.6%), P3 (−8.7%, p = 0.06), and P7 (−11.1%), in comparison with FREE. Gender did not influence the effect of either back-support exoskeletons on ES muscle activity. These results point to the need for particular attention with regard to (1) exoskeleton design (rigid versus soft) and to (2) the range of trunk motion, when selecting an EXOBK. In practice, the choice of a passive back-support exoskeleton, between rigid and soft design, requires an evaluation of human-exoskeleton interaction in real task conditions. The characterization of trunk kinematics and ranges of motion appears essential to identify the benefits and the negative effects to take into account with each exoskeleton design.

Influence of a passive back support exoskeleton on simulated patient bed bathing: results of an exploratory study

“…More importantly, the use of the Laevo induced a large increase in trunk forward flexion, from 20 deg in average without the exoskeleton to 33 deg with it. While postural changes are not systematically observed (e.g., Madinei et al (2020)), this finding is aligned with those reported by several other studies on the Laevo, in a patient transfer task (Hwang et al, 2021), in lifting tasks (Koopman et al, 2020;Schwartz et al, 2021), and in a manual assembly task (Bosch et al, 2016). Those studies consistently observed an increase in trunk forward flexion when wearing the Laevo, often around 5 deg but the magnitude varies (in some studies, the trunk inclination was loosely constrained, which might have limited the extent of the postural change).…”

“…This should increase the hand manipulability, thereby resulting in more efficient and comfortable arm postures (Jacquier-Bret, Gorce, & Rezzoug, 2012). The fact that increased trunk flexion was observed in several other studies where the environment was less constrained suggests that it is rather the result of a choice due to the more favorable mechanical demand created by the exoskeleton, as suggested in Schwartz et al (2021) and Bosch et al (2016). However, the present study does not allow to conclude with certainty.…”

“…Several passive back support exoskeletons are now commercially available and have been evaluated for industry-oriented activities in laboratory experiments (Baltrusch et al, 2018;Bosch, van Eck, Knitel, & de Looze, 2016;Jelti et al, 2021;Koopman, Kingma, Faber, de Looze, & van Dieën, 2019;Madinei, Alemi, Kim, Srinivasan, & Nussbaum, 2020;Picchiotti, Weston, Knapik, Dufour, & Marras, 2019;Poon, van Engelhoven, Kazerooni, & Harris, 2019;Schwartz, Theurel, & Desbrosses, 2021;Wei et al, 2020;Whitfield, Costigan, Stevenson, & Smallman, 2014), as well as in field testings (Amandels, het Eyndt, Daenen, & Hermans, 2018;Graham, Agnew, & Stevenson, 2009;Hensel & Keil, 2019). Those studies generally agree on the efficacy of back support exoskeletons in reducing metabolic cost, lumbar muscle activity or perceived back force exertion during activities involving trunk flexion in the sagittal plane.…”

Active and Passive Back-Support Exoskeletons: A Comparison in Static and Dynamic Tasks

“…In [12] and [13], the authors compared two passive (relying on purely mechanical elements) commercially available BSEs, the BackX model AC (SuitX, Emeryville, California, USA) and the Laevo v2.56 (Laevo, Rijswijk, the Netherlands), during a series of dynamic tasks (e.g., repetitive symmetric load-lifting) and pseudostatic working postures. Similar works have been described in [14] and [15]. Studies of this type can help to guide the selection and application of passive BSE devices under diverse conditions.…”

Exoskeletons and Exosuits Could Benefit from Mode-Switching Body Interfaces That Loosen/Tighten to Improve Thermal Comfort

“…Exos are used in a range of different applications, such as clinical [ 5 ] and occupational [ 6 ]. Exo research has primarily focused on device design and validation that exos reduce muscular demands, effort, or fatigue [ 7 , 8 ]. Despite the focus on exos as physical assistance devices, frequently the key barriers to societal adoption are related to comfort, fit, and freedom of movement [ 9 ].…”