Design of Lower Extremity Rehabilitation Robots with Magnetorheological Dampers and Wire-Driven System

Abstract

Lower extremity rehabilitation robots play significantly important role in rehabilitation medicine, which aims to bring back the capabilities of patients’ lower limbs because of illness, injury and disease. However, controllability, energy consumption and control precision of the robot motion remain difficult to solve out. In many cases, electric motors are required to have high output torque to move the entire machine legs along with human legs, while extravagant motor torque may lead to excessive bending, fracture or other secondary damages. And the motors would generate the braking torque to prevent this at the cost of consuming large armature current. Controllable braking torque also counts while patients’ active anti-resistance training. Smart materials have provided inspiration and magneto-rheological (MR) fluids vary in rheological behavior with responding to applied magnetic field. Based on the characteristics, magnetorheological dampers (MR dampers) were developed and have realized variable damping resistance according to different magnetic field. Besides, wire-driven system is another guarantee of safety and controllability due to its flexible structure and compliant control. So, with combination of MR dampers and wire-driven system, the lower extremity rehabilitation robot would perform better, more efficiently and more safely. Actually, such robot can hardly be seen in previous related research or publication. In this paper, three kinds of rehabilitation robots with MR dampers and wire-driven system are introduced. They are standing/walking rehabilitation robot with cylindrical dampers, standing/walking rehabilitation robot with discal dampers and sitting/lying rehabilitation robot with discal dampers. Their advantages and drawbacks are also explained.