AGREE: A Compliant-Controlled Upper-Limb Exoskeleton for Physical Rehabilitation of Neurological Patients
Stefano Dalla Gasperina, Marta Gandolla, Valeria Longatelli, Mattia Panzenbeck, Beatrice Luciani, Francesco Braghin, Alessandra Pedrocchi
Abstract
In this work, we introduce the AGREE exoskeleton, a robotic device designed to assist in upper-limb physical rehabilitation for post-stroke survivors. We detail the exoskeleton design at the mechatronic, actuation, and control levels. The AGREE exoskeleton features a lightweight and adaptable mechanical design, which can be used with both the right and left arm, supporting three active degrees-of-freedom at the shoulder and one at the elbow. The device embodies a spring-pulley anti-gravity system to minimize torque requirements and has torque sensors on each joint for safe and smooth interaction with the user. The AGREE control system, which employs a loadcell-based impedance control method, offers various modes of human-robot interaction, such as passive-assisted, active-assisted, and active-resistive exercises. Results from our experimental characterization demonstrate that the exoskeleton is capable of both compliant and rigid behavior, providing a wide range of haptic impedance and transparent behavior to both user-generated and therapist-generated forces. Our findings indicate that the AGREE exoskeleton may be a viable option for safely assisting patients with neurological conditions.