A Comparison of Optimized and Stride-Wise Adaptive Control on the Biomechanical Effects of Personalized Ankle Exoskeleton Assistance During High-Speed Walking

Abstract

Abstract. This study systematically compares two personalized control strategies for ankle exoskeletons: human-in-the-loop (HIL) optimized torque profiles and stride-wise adaptive torque control. Through biomechanical analysis of 11 healthy participants walking at 1.50 m/s, we evaluated these approaches across multiple performance metrics. Both strategies demonstrated comparable effectiveness in reducing soleus (SOL) muscle activity (36.8% versus 35.8%) and biological ankle torque (34.1% versus 36.6%), with no significant differences observed at the group level (p > 0.05). However, the optimized torque mode showed 22.4% higher energy efficiency (1.189 versus 1.793 J/kg reduction in muscle activity) and induced less compensatory tibialis anterior (TA) activation (p < 0.05). While gait symmetry remained unimpaired (p > 0.05) under both modes, individual responses varied substantially, particularly in adaptation to dynamic parameter adjustments. These findings indicate that pre-optimized fixed parameters are preferable for stable walking conditions, whereas adaptive control requires further refinement for dynamic environments, providing empirical guidance for selecting ankle exoskeleton control strategies based on application needs.