Abstract

Rehabilitation of patients suffering after stroke impairment is a lengthy process and requires experienced therapists. These limitations have led to the introduction of rehabilitation robots that can operate for a longer time while eliminating the lack of professional therapists. In this thesis, we propose a two-degrees-of-freedom robot for wrist rehabilitation, referred to as MOCH. The MOCH mechanism comprises a remote center of motion (RCM) mechanism with a rotation center outside of the robot structure.
When the patient holds the robot end-effector, coinciding the RCM of the robot with the rotation axis of the wrist, allows pure rotational motion of the hand.
As the RCM lies out of the robot structure, there is less risk of interference with the patient. Furthermore, MOCH benefits a novel actuation that enables the actuators to be grounded, reducing the inertia and the size of the robot. The optimal design of MOCH is provided considering the mechanical criteria and requirements of the wrist rehabilitation. Based on the proposed design, a prototype of the robot is developed with a total mass of 1.3 kg using 3D printing technology. Additionally, we introduce a novel methodology for passive rehabilitation exercise, exploiting the wrist dynamics which removes the complexity of force/impedance control approaches. This method involves designing an optimal trajectory within the limits of the wrist motion, and to keep the applied torque on the patient's hand in a safe range without using force sensors. The proposed trajectory is tested on a healthy individual using the implemented prototype.