Design And Development Of Unilateral Lower Extremity Exoskeleton System

With the intensified population aging and the increasing incidence of stroke and osteoarthritis,the rehabilitation exoskeletons for patients with lower extremity motor dysfunction gradually become a hotspot in medical field.Patients of hemiplegia and lower extremity osteoarthritis have difficulty in standing and movement.In present,the daily rehabilitation training is mainly accomplished by the guidance of physiotherapists.Rehabilitation exoskeletons can be used to assist or replace physiotherapists in rehabilitating patients,which reduces the required labor costs and adapts to different individuals.Rehabilitation exoskeletons can help patients burden the body weight to release the joint pain and provide gait training of higher precision to patients.This thesis gives a design of a unilateral lower extremity exoskeleton which predicts the gait trajectory of the hemiplegic limb from the measured motion data of the healthy limb and reduces the joint forces of the patient in the gait training.The mechanical structure of an active medial lower extremity exoskeleton is designed based on the research on the human lower extremity motion mechanism.According to the similarity of the movement of lower limbs in two sides,the control strategy is designed to make the healthy leg teach the hemiplegic leg.A real-time gait measurement system based on inertial sensor is developed to obtain real-time gait data of the healthy leg and a gait phase separation method which is based on neural network model offered by off-time training with plantar pressure data and fuzzy phase separation method is proposed.The preset trajectory of the hemiplegic limb is given by the real-time measured joint angle data of the healthy limb and implemented by a servo-driven control system based on the embedded controller and gait phase separation method.The actuator of the exoskeleton is controlled by the cascade PID controller to realize the strategy of guiding the exoskeleton to assist the hemiplegic limb by the healthy limb.Finally,the function of the exoskeleton is verified by the limb tracking experiment and the weight reduction gait training experiment on the prototype of the designed exoskeleton.The experiment results show the feasibility of the control strategy of guiding the hemiplegic limb by the healthy leg and the validity of reducing human joint burdens in gait training.