A New 4-DOF Robot for Rehabilitation of Knee and Ankle-Foot Complex: Simulation and Experiment

These authors have contributed equally to this work. Abstract Stationary robotic trainers are lower limb rehab robots which often inco rporate an exoskeleton attached to a stationary base. The issue observed in the stationery trainers for simultaneous knee and ankle - foot complex joints is that they restrict the natura l motion of ankle - foot in the rehab trainings due to the insufficient D e grees of F reedom (DOFs) of these trainers. A new stationary knee - ankle - foot rehab robot with all necessary DOFs is developed here . A typical rehab training is first implemented in simulation, and then tested on a healthy subject. R esults show that the prop osed system functions naturally and meets the requirements of the desired rehab training . I ntroduction Damage to the nervou s system, caused by accidents such as stroke and spinal cord injuries, often lead s to movement disorders [1] . This issue is of practical importance, a s it can severely hamper activities of daily living for the survivors, in light of the large number of stroke incidents per year [2] . To address this issue, patients take rehabilitation exercises under the supervision of therapists to regain their a bilities. During the last two decades, rehabilitation exercises have received sig nificant attention from robotic researchers. Many robots have been designed to facilitate rehab trainings for both patients and therapists, and to improve the training result s in terms of repeatability, reliability and accuracy in evaluating the patient ' s progress [3] . Among the developed platforms, lower limb rehab robots are of more impo rtance, since they have a direct effect on gait. The lower limb rehab robots can be divided into two general types: standing/walking and sitting/lying. The standing/walking robots mainly aim to correct the gait pattern in conditions similar to daily life.