Research On Human Motion Identification And Control Based On Multi-Sensor Fusion

The number of patients with lower extremity dysfunction caused by aging population and stroke is increasing every year in China,the patients that lost part or even all sport ability have brought heavy burdens to society and families.Rehabilitation of pe-ople with motor impairment has became a society problem that must be faced.Traditional rehabilitation methods for the people are basically one-to-one rehabilitation treatment by rehabilitation physicians.This therapy not only brings great labor burden to physiotherapists,but also reduce the efficiency of rehabilitation treatment.Besides,there is a huge gap in the number of physiotherapist engaged in rehabilitation therapy in China,which is far from meeting the needs of the reality of our country.Based on the above situation,the research on rehabilitation robot emerged.Rehabilitation robots have great advantages in rehabilitating physiotherapists,which can greatly reduce the workload of rehabilitation physiotherapists.On the other hand,rehabilitation robot can provide comprehensive,scientific and efficient training for patients because its design conforms to the biomechanics and ergonomics of human.In this paper,we first introduce the lower limb skeleton,joints and major muscle clusters based on human anatomy.There are 62 bones in the lower limbs of normal human body,including femur,tibia,fibula and foot bone.As the longest and strongest bone in the human body,femur plays an important role in supporting the human body.The tibia,as the main bone in the calf bone,bears most of the body's self-weight.The three lower extremity joints,hip,knee and ankle,provide a total of seven degrees of freedom to meet human movement needs.Lower extremity muscles are more robust than upper extremity muscles because they need to provide more power.Finally,a kinematics model of human body including upper body,thigh,shankand foot is established and the formulas for calculating the moment of each joint of lower limb are deduced based on the model.In order to meet the needs of the experiment,a data acquisition system including force sensing signal,kinematics sensing signal and surface electromyography signal is built in this paper.Using Arduino UNO MCU as data processing unit,the full bridge circuit composed of four YZC-161 B pressure sensors is selected to measure the vertical reaction force of seat surface and the vertical reaction force of ground.Three kinematic signals are collected using the extensible six-axis kinematics sensor mpu6050 and serial multiplexer PCA9548 AD.Surface EMG signals are collected using three-channels surface EMG signal acquisition unit,high-speed analog data acquisition card PCI-1713 U and Labview.In this study,10 healthy men were selected to participate in the experiment.The movement posture,joint moment and the muscle contribution of the five muscles selected in the lower limbs during the sit-to-stand(STS)were analyzed and studied in detail.The experimental results show that the upper body always starts to move first in the process of standing up.When the forward swing of the upper body has not reached its maximum,the knee joint begins to flex and stretch,and then the whole body begins to stretch until it stands completely.During the STS,The main contributions of lower extremity muscles are concentrated before seat-off,and after seat-off,the contribution of lower extremity muscles decreases significantly.The experimental results preliminarily reveal the human body's own control strategy in the STS,which provides a theoretical basis for the subsequent development of rehabilitation robot.