Review on Sliding Mode Controller and Its Modified Types for Rehabilitation Robots

Recent advancements in the field of rehabilitation robotics have led to the development of variety of exoskeletons that are used extensively during therapeutic exercises for the poststroke patients. These robotic devices are meant to provide ease and comfort to the patient undergoing therapy, so controlling these robots effectively is very crucial. Widely used control algorithms for controlling these devices are linear controllers which are not much robust and efficient as compared to non-linear controllers. Since rehabilitation robots are highly nonlinear in nature, therefore nonlinear controllers are required that can perform well under uncertainties and resistant to parametric changes. One of the most extensively used non-linear control method is Sliding Mode Controller (SMC). SMC has proved its robustness in terms of trajectory tracking, stability and insensitiveness to disturbances and parametric uncertainties. One drawback of using classical SMC is chattering, which is high frequency oscillations. This paper presents sliding mode controller and its different types along with the method of chattering removal, for controlling rehabilitation robotic devices.