Control system design of an active assistive exoskeletal robot for rehabilitation of elbow and wrist

Physical disabilities in elbow and wrist are very common in elderly people or people who are suffering from an injury or a stroke. Therefore, developing an assistive wearable robot seems essential. Herein this paper a simple novel control algorithm is proposed and implemented for controlling the position of a wearable assistive robot. The robot is used for rehabilitation of wrist and elbow and has 3 Degrees of Freedom (DOF); two active DOF for assisting flexion/extension of elbow and wrist, and a passive one in order to have unconstrained supination /pronation of forearm. The proposed control system incorporates force signals and trigger commands issued by the patient to track patient's desired trajectory. Furthermore with the intention of evaluating performance of the robot and the control scheme, some preliminary experiments are conducted using the prototype of the designed wearable robot on a human subject with spinal cord injury (SCI). Experimental results showed that the proposed assistive robot meets its design goals and it is successful in tracking the patients' desired trajectory without harming the patient.

I. Introduction

IN the recent years, number of peoples suffering from physical disabilities such as full or partial loss of function in shoulder, elbow or wrist has been increasing rapidly. Sports injuries, occupational injuries, spinal cord injuries and strokes are some of the main reasons for such disabilities. Rehabilitation programs are the main treatment for these kinds of patients. In order to assist physically disabled, injured, and/or elderly persons or to ease their rehabilitation treatment, researchers have been developing exoskeleton robots.