Robot-Borne PLC-Based Control System Used for Lower Limbs Rehabilitation

Abstract

The purpose of this investigation is to study control and monitoring of a rehabilitation robot with two degrees of freedom (2-DOF) for rehabilitation of the lower limbs of patients with loss of ability for movement due to injury, disease, stroke or surgical operations. After determining the movements which include flexion-extension movements of the knee and hip joints, the performance of the mechanism was investigated using dynamic analysis and simulation. Then, a programmable logic controller (PLC) was employed to control the robot performance. Finally, the accuracy of PLC program was guaranteed by monitoring the robot. Passive, assistive and resistive exercises were considered in programming the controller. In assistive exercises, the forces needed by the patient to perform the movements were actually set automatically by using the feedback data provided by the patient's forces. In addition, to perform the resistive exercises, rather than using actual weights, negative loads were employed. The results obtained indicate considerable accuracy to perform the movements and create safe conditions for the patient. Also, high flexibility in programming provides the possibility of performing a wide range of rehabilitation exercises.