Omnidirectional Mobile Robot for Upper Limb Rehabilitation Based Mirror Therapy

The design, development, and evaluation of an omnidirectional mobile robot system for upper limb rehabilitation based on mirror therapy are presented in this paper. The system consists of two main parts. The first part is a 2 DOF passive arm. It is utilized in transferring the motion of the user/patient healthy arm to the omnidirectional mobile robot. The second part is an omnidirectional mobile robot which a 6 DOF force-torque sensor is attached to its gripper. This robot has the responsibility for assisting the movement of the user/patient impaired arm according to the trajectory received from the passive arm and a force that the user/patient exsert to the robot's gripper. An admittance control method is applied in this system to control the motion of the robot depending on the external force. To evaluate the system, three experiments were set up. The results indicate that the robot with an admittance control can respond to the external force within 54 ms. The step response of this system consists of 105 ms of response time with 6.24% overshoot and the steady-state error is 4.32%. Furthermore, the robot can track the desired trajectory properly.