Reserch On Drunk-driving Detection Method Based On Impedance Spectroscopy Plethysmography

The drunk driving test is an important means of traffic law enforcement in the traffic police department The traditional blood sampling test method has poor timeliness and can not be quickly measured on site.The breath test method has some shortcomings such as inaccurate measurement results and can not be used continuously.The new detection methods of saliva,sweat and urine are in the research and exploration stage.In addition,there are on-board drunk driving detection methods and non-contact drunk driving detection methods.These detection methods are affected to varying degrees by the environment and detection methods,and have certain limitations.Studies have shown that excessive alcohol in the blood can lead to changes in hemorheology and electrical conductivity of the blood,while impedance plethysmography(IPG)reflects the hemorheology of the blood,and bioelectrical impedance spectroscopy(BIS)reflects the electrical conductivity of the blood.According to this,this thesis proposes a new method of measuring ISPG,which combines IPG technology and BIS technology,and explores a new method of alcohol driving detection based on ISPG measurement.The main research contents are as follows:(1)On the basis of reviewing the development and research status of alcohol driving detection and bioelectrical impedance technology,this thesis systematically expounds the basic concepts of traditional IPG and BIS technology,as well as the measurement principle and implementation method of the new ISPG method,and analyzes the feasibility of alcohol driving prediction method based on ISPG measurement.(2)Designed a set of ISPG measuring instruments for drunk driving detection,completed the hardware circuit design and software system design of the measuring instruments,including FPGA main control module,excitation signal generation and data acquisition module,as well as data processing and data display storage module.The instrument measures the impedance between human arm and arm by measuring electrode.The measured data are transformed by FFT and CORDIC to obtain the amplitude spectrum and phase spectrum of human impedance,and the amplitude and phase spectrum waveforms are displayed by LCD screen.(3)The ISPG measuring instrument is calibrated by Lagrange quadratic interpolation method,and the error analysis of the measuring system is carried out by the measurement of three elements.The relative error of impedance amplitude is 0.02%～0.81%,and the phase error is 0.08 °～1.37 °.(4)The anthropometric experiments is carried out with ISPG measuring instrument designed in this thesis.The impedance of arm to arm,arm to leg and neck is measured respectively,and the arm to arm measuring circuit is selected finally.The ISPG measurement experiment of human body under the condition of drinking is carried out,and the experiment shows that the impedance amplitude of human body decreases with the decrease of alcohol concentration.Finally,the prediction model of alcohol driving based on ISPG measurement is established by partial least square method.