I. Introduction
With the coming of aging society in China, the amount of dysfunctions patients caused by physiological recession have increased dramatically. In addition, nerve damage or physical injury patients also increased significantly by traffic accidents, injury, disease, war, disaster and other causes. Besides early surgery and drug treatment, Rehabilitation training plays a very important role for the recovery of patients [1]. Therefore, the rehabilitation robot technology especially the lower limb rehabilitation robot technology has become a hot filed in recent years.