ANYexo: A Versatile and Dynamic Upper-Limb Rehabilitation Robot

This letter presents a versatile upper-limb exoskeleton based on low-impedance torque controllable series elastic actuators. This experimental platform is designed to validate novel algorithms and hardware concepts for more autonomous therapy of moderately and severely affected patients with a neural impairment. The design is optimized to achieve a large range of motion (ROM) and robust interaction force control to best mimic the compliant and accurate haptic interaction of therapists. The presented robot covers the relevant ROM required for activities of daily life (ADL) particularly, including poses close to the torso, head, and behind the back. The kinematics are optimized for high manipulability during ADL and low inertia. We use modified modular series elastic actuators that provide the required power and torque control performance. We demonstrate highly transparent behavior up to speeds of 11 rad/s with a feed-forward torque controller based on an accurate dynamic model. The presented robot unites a large ROM with optimized manipulability, high nominal power to weight ratio (111 W/kg), accurate torque control at speeds sufficient for unconstrained recovery of patients, and versatility for a broad variety of experiments in one device. To our knowledge, no other device is tailored to such an extent for this application.