RANK - Robotic Ankle: Design and testing on irregular terrains

• Main Authors: Taborri, J., Mileti, I., Mariani, G., Mattioli, L., Liguori, L., Salvatori, S., Palermo, E., Patane, F., Rossi, S.
• Format: Conference Proceeding
• Language: English
• Subjects: Control systems; Exoskeletons; Legged locomotion; Real-time systems; Robot sensing systems; Timing; Torque
• ISSN: 2153-0866
• DOI: 10.1109/IROS47612.2022.9981580

Despite the large amount of available exoskeletons, their use in daily life is still limited due to the absence of testing in real-life environments. Thus, the present work aims to test on a series of uneven terrains a wearable ankle exoskeleton, named RANK, designed for walking assistance and drop-foot prevention. RANK consists of a 3D-printed brace attached to the user and a piezoresistive insole, to be incorporated into the user's shoe. Real-time analysis of the insole's sensor outputs enables the control system to provide torque assistance to the ankle joint through a four-bar linkage mechanism. Two healthy male subjects were enrollee, asking them to walk on three different terrain conditions (flat, soft, and irregular) with and without exoskeleton. Human kinematics was gathered via inertial measurements units (IMUs). The effects of ankle exoskeleton on lower limb joint angles were assessed in terms of range of motion (ROM), whereas statistical parametric map method was applied to compare joint angle curves. As expected, a reduction of the ankle ROM approximatively of 10° was found in all terrain conditions between the trails performed with and without exoskeleton. No effects induced on the hip and knee joint were observed. Moreover, no significant differences were found over the almost totality of the gait cycle regardless the terrain conditions. Results demonstrate the capability of the exoskeleton to work properly regardless the type of walking surface.