# Method and Test Course for the Evaluation of Industrial Exoskeletons
## 1 Introduction  
The daily use of exoskeletons attains increasing interest in industrial environments. As a human-centered approach, exoskeletons provide physical support to the workforce, and thus may prove successful in preventing work-related musculoskeletal disorders (WMSD) in the long term [1, 2]. In industrial applications, WMSD are mainly caused by demanding working conditions such as strenuous and repetitive movements, or awkward working postures, occurring in, e.g., assembly and logistics tasks and potentially leading to the workforce's absences, presentis, or a reduction in quality of life [3]. Recently, the number of commercially available exoskeletons for industrial applications in production and logistics has risen sharply [4]. The systems support different body parts such as the upper extremities, trunk, or lower limbs as well as featuring various technical properties, morphologies, and kinds of support [2, 5]. Thus, potential users of industrial exoskeletons face the decision of selecting the most appropriate system [6, 7], as necessary information about exoskeletons is either differently labeled or generally lacking. For instance, this concerns various characterizations of the system's support, clear application guidelines (e.g., regarding wearing time, risk assessment, hygiene, maintenance), or specifications of technical characteristics (e.g., regarding actuators, force curves, operating times) and operational requirements (e.g., regarding movability, compatibility with personal protective or working equipment). Additionally, study results depend on the respective study setup (e.g., selection of the system's power level, sample's characteristics, or selected tasks with their properties) [8] and should thus only be viewed in the context ofeach investigation [9]. Besides, the evaluation methodologies for industrial exoskeletons are not standardized [10] and often analyze limited constructs or items with different testing procedures and methods applied on less representative samples [11]. 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]). These days, several initiatives for harmonizing the description and especially the evaluation of industrial exoskeletons in both regulatory committees (e.g., American Society for Testing and Materials (ASTM) Committee F48, European Committee for Standardization (CEN) CWA 17664:2021) and scientific communities take place. For instance, the ASTM works on standards for labeling, training, operating, and testing practices [18]. The CEN proposes a performance test method for walking on uneven terrain [19]. The EUROBENCH project aims to develop various tools to assess and benchmark robotic systems considering multiple aspects [20]. Additionally, scientific reviews provide informative overviews of applied evaluations of either exoskeletal prototypes or commercial systems. For instance, they focus on the user's metabolic costs with upper-body exoskeletons [21] or muscular activity, body loading, and experience with trunk exoskeletons [22; 23]. In contrast, [PERSON] et al. [11] present a generic prevalence matrix of different applied types of analysis combined with their respective research objects for deriving patterns and best practices for prospective evaluation methodologies. Besides, [PERSON] et al. [24] investigate the statistical effects of exoskeletons on biomechanical stress and strain through a meta-analysis. Other approaches introduce different kinds of standardized test environments for uniformly evaluating, benchmarking, or comparing exoskeletons by passing representative test tasks, stations, or batteries of specific application profiles.