Optimized design of lower limb exoskeleton based on human biomechanical analysis.

To address the current issue in exoskeleton research and development, where studies on the impact of exoskeletons on human muscles and bones are often overlooked prior to prototype manufacturing, leading to prolonged design cycles and high R&D costs, this study proposes a passive lower-limb exoskeleton optimization design method. Using AnyBody software, an exoskeleton-musculoskeletal coupling model was established for biomechanical analysis, and the structural parameters of the lower-limb exoskeleton were optimized. First, a lower-limb exoskeleton model tailored to the individual dimensions of the test subject was designed in SolidWorks software and imported into AnyBody to establish a human-machine coupling model for inverse dynamics simulation. The effects of different torsion spring stiffness values on human knee joint forces, metabolic rate, and muscle activation were analyzed. The optimal torsion spring stiffness values were obtained by setting the objectives of minimizing knee joint forces and metabolic rate in order to investigate the assistive effect of the exoskeleton. Experimental results showed that when the torsional spring stiffness of the knee joint module of the lower-limb exoskeleton was 75 Nm/rad, the knee joint forces and metabolic rate of the human body were at their lowest, indicating that the designed exoskeleton provided optimal assistive effects, with a significant reduction in the activation levels of the major lower limb muscles. Additionally, when comparing the surface EMG signals collected from participants without the exoskeleton during the experiment with the simulation results, the correlation coefficients between the simulation data and experimental data were all above 0.976 (P < 0.05), indicating a high degree of correlation between the two. However, it should be noted that this experimental validation was conducted only under conditions without exoskeleton wearing, and the predicted optimal stiffness and its effects on reducing knee joint forces and metabolic rate are still theoretical and require further verification through physical prototype experiments. The proposed analysis and optimization design method for a passive lower-limb exoskeleton based on the AnyBody biomechanical simulation software provides insights into the effects of different structural parameters on human muscles and bones, offering new approaches for the low-cost, rapid design and development of exoskeleton products.