A Hybrid Verification Method for an Actuated Lower-Limb Exoskeleton Based on Mathematical and Simulation Analyses

Abstract

This study proposes a hybrid method for pre-design verification of the geometric and biomechanical compatibility of experimentally recorded gait trajectories with a lower-limb exoskeleton. The method integrates joint-space kinematic analysis, CAD-based self-collision detection in a Unity digital twin, anatomical hip and knee constraints, and experimentally recorded gait trajectories. Gait data were obtained from 30 healthy participants at 12 treadmill speeds ranging from 0.5 to 6.0 km/h using multicamera markerless motion capture. Of 54,481 evaluated configurations, 21,450 remained after self-collision detection and 4080 after anatomical filtering, corresponding to 7.49% of the initial discretized domain. The mean proportion of experimental trajectory points excluded because of mechanical self-collisions increased from 2.70% at 0.5 km/h to 30.49% at 6.0 km/h. Walking speed had a significant and large overall effect (χF2(11)=242.38, p<0.001, Kendall’s W=0.734), and the median participant-specific Spearman coefficient was ρ=0.920. The proposed framework provides a quantitative pre-screening tool for identifying critical gait configurations before powered prototype testing and can support mechanical redesign and definition of controller constraints.