Investigation into torque-matching-based lower limb flexibility control technology for exoskeletons

Abstract The flexibility of lower limb exoskeleton joint control significantly influences the user’s wearing experience and the effectiveness of assistance. This paper introduces a novel method for enhancing the flexibility of lower limb exoskeleton control based on moment matching. Initially, we investigated the characteristics of human lower limb joint torques under various gait conditions, obtaining detailed data on hip, knee, and ankle joint angles and torque profiles across different slopes and loads. Subsequently, by leveraging gait phase recognition results, we determined the optimal assisting timing. Specifically, the phase angle was utilized as the control input to design the dynamic assist curve for the hip joint pendulum motion, while the knee joint angle served as the control input for designing the support state assist curve of the knee joint. Experimental results demonstrate that this method effectively adapts to changes in hip and knee dynamics during human movement, providing assistance values that align with biomechanical characteristics.