Implementation of a task-dependent anisotropic impedance controller into a 2-DOF platform-based ankle rehabilitation robot

Inspired by achievements in rehabilitation, motor learning, and neuroscience, therapeutic robots are aiming to provoke neuromotor plasticity and improve recovery after stroke and mobility impairments. Human sensorimotor system is specialized with position and velocity sensory fibers and exhibits variant muscle impedance in accordance with the ongoing task. The virtually interfaced robotic ankle and balance trainer (vi-RABT) was introduced as a cost-effective platform-based rehabilitation robot to improve overall ankle / balance strength, mobility and control. This study is the first step toward assistive / resistive ankle rehabilitation using vi-RABT. We have implemented a task-dependent anisotropic impedance controller into the 2-DOF ankle rehabilitation robot. An objective virtual Maze game is developed. The controller is specifically designed for the Maze workspace; and exhibits elastic or pure viscos properties in compliant with the subject´s direction of movement. Early results on two human subjects are presented.