Research Of The Body Weight Support And Physical Sign Monitoring System For Lower Extremity Rehabilitation Training

With the development of society and the aging of population,patients with lower limb injury and nervous system disease become more and more.Owing to their insufficient lower extremity ability to bear their own weight,the gait rehabilitation training should be taken to help them to correct gait,improve balance and recover basic walking ability.At present,the body weight support system is mainly divided into passive system and active system,the passive system realizes the loss of weight through the counterweight,spring,winch;the active system realizes the loss of weight through the air pressure,hydraulic and motor drive.Although the body weight support system has positive effects on the recovery of the lower extremities,the patients may have discomfort due to the influence of patient's own disease and the fatigue intensity of exercise,which will affect the safety and effectiveness of rehabilitation treatment.Therefore,an active body weight support system is designed,which can monitor patient's physical parameters in rehabilitation training,including the structure design,the control system of body weight support system and the physical sign monitoring system.The main contents of the research are as follows:(1)The structure design of the body weight support system: first,the existing systems at home and abroad are investigated and the overall scheme is put forward;secondly,the weight loss mechanism module is designed,including: gears,spool,fixed pulley mechanism and so on;thirdly,the suspension module is designed,including material selection,structural analysis,strength analysis and comfort analysis;finally,the bracket is designed.The structure of the system is simple,comfortable and reliable and meets basic weight loss needs.(2)Research on the control of the body weight support system: first,the mathematical model of each module is established to get the dynamic equation;then the control system scheme is put forward and the model is analyzed,namely,PID control method.The error between the actual gravity collected by the sensor and the theoretical gravity is used to control the motor to maintain the gravity constant;finally,the simulation of the control system is carried out through the Simulink to verify the feasibility of the control system scheme.The simulation results show that the control method is equipped of smaller errors,faster response speed and can be applied to the gait rehabilitation training under different gravity and moving speeds.(3)Research of the physical sign monitoring system: first,the current methods of physical sign monitoring system are investigated and the advantages and disadvantages are analyzed;secondly,a physical sign monitoring system based on the gas pressure sensor is designed according to the different frequency and force;the system includes the pressure sensor,operation amplifier circuit,bandpass filter circuit,adding circuit and so on,the methods of sliding average filtering,butterworth filter,FFT,differential are used to get the heart rate and breath.The method is comfortable and reliable and can monitor heart rate and respiratory parameters simultaneously.(4)The prototype is made and the experiments are carried out: first,the prototype of the system is made including the selection,purchase,machining and assembly of the key components;secondly,the experiment platform of body weight support and physical sign monitoring system is built;finally,the experiments of different gravity and velocity are carried out and the results are analyzed.