A Novel Personalized Ankle Exoskeleton with Co-Located SEA for Gait Training

Gait rehabilitation programs help individuals who sustained a brain injury or severe lower-leg trauma realize their full recovery potential. While robotic exoskeletons have emerged as promising tools for gait rehabilitation, high costs and “one-size-fits-all” designs that sacrifice user comfort and fit hinder their wider adoption in clinical settings. In this paper, we present a new modular ankle exoskeleton featuring a personalized Ankle Unit and a portable Actuation Unit. The Ankle Unit is fabricated using affordable additive manufacturing processes to conform to the user's leg morphology. The Actuation Unit, which can be shared across different Ankle Units, utilizes a cable loop to transfer mechanical power to a lightweight, high-stiffness rotary elastic module co-located with the ankle joint. Preliminary treadmill walking tests indicate very good transparency (root mean square error (RMSE) of 0.27 Nm in zero-torque mode) and torque tracking performance (RMSE of 1.16 Nm when applying 10% biomechanical torque assistance, corresponding to a peak commanded torque of 13.7 Nm),