Wearable Biomechanical Sensing Platform Integrated on Rigid–Flexible Coupled Load-Bearing Exoskeleton: Multi-Terrain Human–Machine Force Monitoring and Physiological Metabolic Validation

Multi-terrain adaptability and metabolic reduction are critical for translating load-carrying lower-limb exoskeletons into practical use. However, conventional single-mode sensing cannot synchronously quantify human–exoskeleton interaction forces and physiological metabolic responses across complex terrains. To address this limitation, this study develops a rigid–flexible coupled load-carrying lower-limb exoskeleton and constructs a dual-modal test platform for interaction force and metabolic energy expenditure. Using DYMH-102 diaphragm box load cells and the Cosmed K5 portable gas metabolism analyzer, a standardized outdoor multi-scenario sensing protocol is established. This protocol quantifies exoskeleton assistance performance and human metabolic benefits under a 15 kg load over three representative terrains: hard level ground (HLG), gently uneven grassland (GUG), and gently sloped mountain road (GMR). The experimental results show that terrain complexity directly affects sensor measurement outcomes and exoskeleton assistance performance: under the three terrain conditions, the shoulder load transfer efficiencies of the exoskeleton are 55.97%, 54.76%, and 42.45%, respectively, and the peak impact load reduction rates reach 78.26%, 80.00%, and 66.67%. A descriptive gradual decline in metabolic saving was observed, likely attributable to terrain perturbations, gait distortion, and human–machine interface slippage, with metabolic cost reductions of 16.28%, 11.93%, and 11.48%. Unlike conventional exoskeleton evaluations relying on isolated performance metrics, this work integrates mechanical and physiological dual-modal sensing to create a synchronous quantitative assessment method for wearable devices in complex outdoor environments. The proposed method mitigates the poor terrain adaptability and lack of multi-parameter coupled evaluation that plague current wearable biosensing systems.