Towards Standardized Testing of Passive Exoskeletons: Methods and Metric Identification

Passive exoskeletons are emerging as a promising solution to reduce physical strain in industrial settings. Unlike active exoskeletons, which use actuators, passive systems use mechanical structures and energy storage elements to assist workers. However, the lack of standardized evaluation protocols makes it difficult to assess their actual impact on ergonomics, safety, and worker well-being, particularly among different user populations. This paper presents a systematic approach to testing passive exoskeletons, focusing on biomechanical impact, usability and acceptance, emphasizing the need for inclusive testing protocols. A total of four industrial passive exoskeletons, two for shoulder support and two for back support, were evaluated on 84 participants, combining objective measures (muscle activity, posture, and stress indicators) and subjective assessments (questionnaires on usability and comfort). Existing evaluation methods are reviewed, and their limitations in the context of passive systems are discussed. Adapted testing strategies are proposed, including motion capture-based posture analysis, assessment of muscle load reduction, and evaluation of usability for workers of different ages, sizes and physical conditions. The urgent need for standardized testing procedures is highlighted, and the potential role of robotic safety regulations in shaping new exoskeleton-specific guidelines is considered. By defining robust and repeatable testing protocols that account for human variability, this work aims to bridge the gap between research and industrial implementation, ensuring that passive exoskeletons are scientifically validated and optimised.