Using a Back Exoskeleton During Industrial and Functional Tasks—Effects on Muscle Activity, Posture, Performance, Usability, and Wearer Discomfort in a Laboratory Trial

Abstract

Objective To investigate the effect of using a passive back-support exoskeleton (Laevo V2.56) on muscle activity, posture, heart rate, performance, usability, and wearer comfort during a course of three industrial tasks (COU; exoskeleton worn, turned-on), stair climbing test (SCT; exoskeleton worn, turned-off), timed-up-and-go test (TUG; exoskeleton worn, turned-off) compared to no exoskeleton. Background Back-support exoskeletons have the potential to reduce work-related physical demands. Methods Thirty-six men participated. Activity of erector spinae (ES), biceps femoris (BF), rectus abdominis (RA), vastus lateralis (VL), gastrocnemius medialis (GM), trapezius descendens (TD) was recorded by electromyography; posture by trunk, hip, knee flexion angles; heart rate by electrocardiography; performance by time-to-task accomplishment (s) and perceived task difficulty (100-mm visual analogue scale; VAS); usability by the System Usability Scale (SUS) and all items belonging to domains skepticism and user-friendliness of the Technology Usage Inventory; wearer comfort by the 100-mm VAS. Results During parts of COU, using the exoskeleton decreased ES and BF activity and trunk flexion, and increased RA, GM, and TD activity, knee and hip flexion. Wearing the exoskeleton increased time-to-task accomplishment of SCT, TUG, and COU and perceived difficulty of SCT and TUG. Average SUS was 75.4, skepticism 11.5/28.0, user-friendliness 18.0/21.0, wearer comfort 31.1 mm. Conclusion Using the exoskeleton modified muscle activity and posture depending on the task applied, slightly impaired performance, and was evaluated mildly uncomfortable. Application These outcomes require investigating the effects of this passive back-supporting exoskeleton in longitudinal studies with longer operating times, providing better insights for guiding their application in real work settings.

An industrial exoskeleton user acceptance framework based on a literature review of empirical studies

“…5.1.6.1 Ease of using an exoskeleton The ease of using an exoskeleton refers to how easy it is to (learn how to) wear, adjust, don and doff the exoskeleton and this topic came up in 17/35 papers. In general, exoskeletons were considered to be easy to use (e. g. Luger et al, 2021). However, an exoskeleton was sometimes also evaluated as being cumbersome (e.g.…”

Challenges and solutions for application and wider adoption of wearable robots

“…Inevitably, the unloading of one part of the body results in an increased loading (i.e., force) on another. In spinal exoskeletons, the reduction of the load to the back is typically achieved via increased loading to the lower limbs, which can be sometimes reflected in increased leg muscle activity (Luger et al, 2021) and discomfort to the chest area (Hensel and Keil, 2019), although back exoskeletons may also reduce leg activity (Bosch et al, 2016;Jeong et al, 2020). In comparison, upper limb exoskeleton interfaces can increase the loading to the spine (Weston et al, 2018).…”

Method and Test Course for the Evaluation of Industrial Exoskeletons

“…Therefore, it takes up the spirit of Bostelman et al [26] by its reconfigurability, modularity, and variability to enable the simulation of the vastness in industrial tasks. Similarly, but advancing to cumulative studies on motoric movements (e.g., [27]) as well as industrial tasks (e.g., [16,25]), a sequence of test activities and movement profiles is arranged in the test course and operationalized as a test battery. It is more holistic since it is not limited to isolated industrial tasks or types of analysis but considers an integrated evaluation of necessary boundary conditions and situations for using exoskeletons.…”

“…Focused tasks in evaluation studies often consider a fraction of workplace settings, and thus only cover restricted patterns of manual activity profiles and their requirements. Evaluators also often admit further study limitations concerning, e.g., reductions in the broad scope of possible activities or user profiles (e.g., [12][13][14][15]) as well as the focus on short-term effects (e.g., [16,17]).…”

“…Baltrusch et al [28] and Kozinc et al [29] assess the functional performance of trunk exoskeletons with objective observations or quantitative and subjective measures on several motoric tasks, respectively. In this respect, Luger et al [16] additionally simulate industrial tasks such as pallet box lifting, fastening, and lattice box lifting, arranged in a triangle orientation for considering pathways. Alternatively, (wearable) robots are compared and discussed in the frame of, e.g., RoboCup [30], Exoworkathlon [31], or Cybathlon [32].…”