| Parkinson’s disease（PD）has become one of the main threats to the elderly in China.It is a neurodegenerative disease.One or more parts of the body have tremors and involuntary tremors,motor retardation,muscle stiffness,gait disorders and balance problems caused by it.Gait analysis is an important means to recognize the movement symptoms of Parkinson’s disease,which can assist doctors to make accurate diagnosis.The traditional contact gait signal detection methods,such as the three-dimensional platform force measurement system and the pressure test panel system,are pressure sensors made of inorganic rigid piezoelectric materials,which have the disadvantages of wearability and poor real-time performance,and have certain limitations for the gait signal detection of Parkinson’s disease.Therefore,effective gait signal detection and processing analysis methods have important research significance for the diagnosis of Parkinson’s disease.First of all,aiming at the short plate of inorganic piezoelectric sensor,this paper proposes a design scheme of composite flexible nano-piezoelectric film based on poly（vinylidene fluoride trifluoroethylene）（PVDF-TrFE）-bismuth chloride（BiCl3）.The previous generation of high-voltage electrostatic spinning equipment was eliminated,and an electrostatic spinning device with controllable temperature and humidity was built independently.A method of preparing BiCl3/PVDF-TrFE composite film by electrospinning was proposed.BiCl3/PVDF-TrFE composite flexible piezoelectric film with different mass fraction of BiCl3 was prepared.The microstructure of the sample fiber of different composite film was observed under scanning electron microscope,and the effect of different mass fraction of BiCl3 on the composite piezoelectric film fiber was investigatedβEffect of phase content.Secondly,a flexible piezoelectric sensor with sandwich structure is designed and packaged with composite film as the functional layer.The open-circuit voltage and short-circuit current of the composite piezoelectric sensor with different mass fraction of BiCl3 are tested by the piezoelectric output experiment.The results show that the PVDF-TrFE sensor with 2 wt%of BiCl3 has the best piezoelectric performance at 30 Hz,and the linearity and repeatability tests prove that the sensor has good output linearity and reproducibility.Thirdly,a single signal acquisition circuit with four modules is designed.The first is the charge amplification circuit which plays the main amplification function.LMC6081 operational amplifier is used as the design core;The second is the voltage amplification circuit of INA128 chip;The third is the bias circuit and power management circuit of NE5532;The last is the filter circuit.Finally,p C and n C signal acquisition and amplification can be realized.Relying on the previous experiments,a6-channel signal acquisition array based on MSP430F5529 Launch Pad single-chip microcomputer platform is designed and verified,which can realize the simultaneous acquisition of 6-channel small signals.Finally,through the basic analysis,this paper obtained the six plantar pressure points with the greatest difference between Parkinson’s patients and normal people when walking,filtered the original signal through the sliding window method,and extracted the temporal characteristics related to the plantar pressure peak.For the gait detection of patients with Parkinson’s disease,a method of plantar pressure recognition during walking based on SVM model is proposed.The experimental results show that the main difference between patients with Parkinson’s disease and normal people during walking is the heel’s pressure,and the accuracy of gait recognition of the two is 81.67%.The research results show that the gait recognition method of Parkinson’s disease based on the insole flexible piezoelectric sensor of BiCl3/PVDF TrFE composite film proposed in this paper has certain system feasibility and progressiveness,and has certain reference value in the fields of plantar pressure and gait recognition. |
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