Mechanical design, simulation and nonlinear control of a new exoskeleton robot for use in upper-limb rehabilitation after stroke

Cerebrovascular accident (CVA) or stroke is one of the main causes of disability. It affects millions of people worldwide. One symptom of stroke is disabled arm function. Restoration of arm function is necessary to resuming activities of daily living (ADL). Along with traditional rehabilitation techniques, robot-aided therapy has emerged in recent years. Robot-aided arm therapy is more intensive, of longer duration and more repetitive. By using robots repetitive dull exercises can turn into a more challenging and motivating tasks such as games. Besides, robots can provide a quantitative measure of the rehabilitation progress. This paper introduces a new robot for shoulder rehabilitation. The shoulder rehabilitation system (S.R.S) has three degrees of freedom (DOFs) for three rotational degrees of freedom of the shoulder. It also allows the additional translational DOFs of the shoulder to avoid discomfort to the patient. A new open circular mechanism is proposed for the third joint. The mechanical structure is designed and optimized in Solidworks and it is based on the properties of upper limb of an adult person. The proposed control algorithm is inverse dynamics control which is intended to be used in passive rehabilitation. The proposed control can efficiently track the desired trajectory and reject constant bounded disturbance input to the system.