Impedance Control of a 6-DoF Robot for Upper-limb Rehabilitation of Children through Combination of Drawing and Physiotherapy Exercises

This paper aims to facilitate the process of drawing geometrical shapes for specific therapeutic exercises that have been developed for disabled children by designing a robust controller for a six-degree-of-freedom (DOF) rehabilitation robot. Primarily, an extensive analysis of the robot kinematics has been conducted in which the first three actuators are actively controlled, and the rest can function passively. Subsequently, and for effective patient-robot interaction, impedance control is utilized. This helps the patients to get a predetermined desired level of assistance from the rehabilitation robot for the intended motions. Simultaneously, the level of assistance will also decrease with the course of recovery of the patient. To assess the performance of the controller, different scenarios have been examined and the results are compared with alternative robotic systems of the literature. By calculating the Root Mean Square Errors (RMSE) of the examinations, it is determined that desired geometrical shapes can be drawn with an accuracy of about one centimeter.