초록

This paper proposes the development of a seven degree-of-freedom (DOF) upper extremity exoskeleton to provide robotic therapy solutions for stroke survivors whose number is increasing along with the trend of ‘Aging Society’. Various robotic solutions have been illuminated and advanced along with their interfacing system in order to promote motor recovery after stroke. From this point of view, the proposed exoskeleton, RearMEX, is developed to (1) achieve active-actuation for the full range of human arm motions through the compact mechanical structure, (2) perform high force transparency through the reduction of the mechanical impedance, and (3) provide a user-interface for customized arm movements in active daily life. Especially, the exoskeleton system has a minimal impedance mode where a user can choose sequential desired postures for constituting a therapy motion by the simple button on the handgrip. Then, given a desired period for the movement, a novel interpolation method named norm-based time-allocating monotone Bézier interpolation is proposed to generate the corresponding trajectory with no jerk at each instant in the operational or configurational space. Furthermore, the disturbance observer (DOB) scheme is applied to achieve a robust tracking control performance on the interpolated trajectory even with model uncertainties and unexpected physical interactions with a wearer. The experimental results verify that the consistent performance can be achieved under various load conditions using the suggested controller.

Keywords

Upper extremity exoskeleton, Rehabilitation robot, Bézier polynomials