A comprehensive review of performance evaluation metrics and state-of-the-art advances in lower-limb exoskeletons

Lower limb exoskeleton technology has emerged as pivotal equipment in three key domains: medical rehabilitation, industrial assistance, and human performance augmentation. The systematization and standardization of evaluations regarding machine performance and human–robot interaction (HRI) are core challenges in transitioning this technology from laboratory research to mature applications. However, evaluation metrics emerging over the past decades have remained fragmented and lack systematic organization. Therefore, this review summarizes the mechanical structures and actuation modalities of common lower limb exoskeletons across these three domains. Starting with an elucidation of the specific evaluation priorities in each field, we review existing metrics – with a particular focus on metabolic cost, data precision, and human–robot compatibility – and construct a multi-level evaluation framework covering three dimensions: the human, machine performance, and HRI. Finally, this paper identifies current potential research focal points and overlooked areas, aiming to provide directional guidance for the future optimization of exoskeleton performance.