ASTM F3474 - 20

    Standard Practice for Establishing Exoskeleton Functional Ergonomic Parameters and Test Metrics

    Active Standard ASTM F3474 | Developed by Subcommittee: F48.02

    Book of Standards Volume: 15.08

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    Significance and Use

    2.1 This practice describes what measure should be performed during the near (hours/days), mid (days/weeks), and far (months/years) stages of exoskeleton evaluation (Fig. 1). The functional conditions and metrics with respect to each task method are assessed from the body area(s) impacted by the exoskeleton (for example, upper body, lower body, or both). These may be within as well as distant to the body areas impacted by the exoskeleton (for example, an upper body exoskeleton may have impacts on the trunk and spine). Desired effects as well as unintended encumbrances to the user’s body are important considerations. The evaluation will occur within the context relevant to the end-use application of the exoskeleton’s implementation. This practice pertains to the industry, military, medical, first responders, and recreational domains, but other domains may arise in the future and will need to be considered. Each domain is unique unto itself; however, the task methods and metrics collected may be unique or overlap across any number of user domains.

    FIG. 1 Exoskeleton Assessment Decision Tree

    Exoskeleton Assessment Decision TreeExoskeleton Assessment Decision Tree

    2.2 Task methods and their metrics are either administered in a laboratory environment, field environment, or both laboratory and field environments. Where not otherwise specified, patient functional outcome measures and pain are key metrics that should be considered for testing performed in the medical domain. Exoskeleton producers or researchers, or both, may also want to consider different types of imaging such as X-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI), ultrasound, and nuclear medicine imaging. Additionally, exoskeleton producers or researchers, or both, may also wish to carry out neuroimaging such as, but not limited to, structural and functional and diffusion MRI, magnetoencephalography (MEG), electroencephalography (EEG), positron emission tomography (PET), or near infrared spectroscopy (NIRS) to understand the cognitive and neurophysiological impacts that exoskeletons have on the brain.

    2.3 Fig. 2 is a Venn diagram that portrays the distinct interactions that may transpire between the user (human), exoskeleton, and task. The interactions are:

    FIG. 2 Exoskeleton Performance Interaction Diagram

    Exoskeleton Performance Interaction DiagramExoskeleton Performance Interaction Diagram

    2.3.1 Human—For example, baseline health, physiology, and job duty assessment;

    2.3.2 Human with an Exoskeleton—For example, fit, comfort, physical size changes, psychosocial considerations, cognitive load, training level, donning/doffing time, and safety;

    2.3.3 Human Performing Tasks—For example, efficiency, speed, agility, power, strength, quality, mobility, time on task, and safety;

    2.3.4 Human with an Exoskeleton Performing Tasks—For example, efficiency, speed, agility, power, strength, quality, mobility, time on task, reliability, and safety;

    2.3.5 Exoskeleton (Exo)—For example, failure mode and effects analysis; material strength and quality; safety factors; cybersecurity; morphological characteristics such as size, shape, and weight; hygiene; cleanliness; integrity; readiness; and durability;

    2.3.6 Exoskeleton Performing Tasks—For example, an automated setup to test mean time between failure, environmental conditions, fatigue and fracture, power usage, or compatibility with other equipment;

    2.3.7 Tasks—A catalog of events either occupational or recreational that a user performs;

    2.3.8 Organization (Org)—The framework within which the user carries out tasks (for example, home, office, and hospital—the users shall adapt to their organization);

    2.3.9 Tools/Equipment—All the technological means, raw materials, and products made available to the user to conduct a work task. The user uses different kinds of tools, no matter what the context, be it private, professional, or medical; and

    2.3.10 Environment (Env)—Constitutes the physical and social atmosphere of the place of the exoskeleton’s use. The external context at the time of the events when the user carries out the task (for example, indoors, outdoors, constrained space (for example, tanks), dirty, humid, hot, cold, dry, wet, and slippery).

    2.4 This methodology indicates considerations that employers/users should use to govern which jobs are more suited to just humans versus humans with exoskeletons. Based on those results, human exoskeleton assessments can be performed using the ergonomic assessment decision chart to determine exoskeleton efficacy with respect to the task(s). From there, the human, exoskeleton, and task(s) are integrated into the organization (where applicable based on domain), tools/equipment, and environment of utilization. Furthermore, when conducting an assessment, please see Practice for Documenting Environmental Conditions for Utilization with Exoskeleton Test Methods for environmental ramifications.2

    2.5 Depending on the context in which the exoskeleton is used (medical, industrial, military, first responders, and recreational), it is necessary to take into account these complementary characteristics to integrate the exoskeletons better.

    1. Scope

    1.1 This practice provides a recommended approach and a set of options for assessing one or more specific ergonomic parameters with respect to human users of exoskeletons.

    1.2 This practice provides functional ergonomic criteria to consider for the design, production, and evaluation of exoskeletons within the domains of industry, military, medical, first responders, and recreational. When designing exoskeletons, natural unassisted human kinematics and kinetics, as well as the resulting strain and fatigue experienced by the user should be salient design parameters. Any changes in the natural unassisted human kinematics and kinetics may impact the exoskeleton’s effectiveness in augmenting user performance. Therefore, the defining principle of this practice is to establish objective measures that can be selected from to assess human kinematics and kinetics, as well as the resulting strain and fatigue experienced by the user within the task context of the exoskeleton’s end use application.

    1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

    1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

    Referencing This Standard
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    DOI: 10.1520/F3474-20

    Citation Format

    ASTM F3474-20, Standard Practice for Establishing Exoskeleton Functional Ergonomic Parameters and Test Metrics, ASTM International, West Conshohocken, PA, 2020,

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