Research On Data Processing Method For Water-Injected Meat Detection System

Water-injected meat(WIM),the fresh meat which is injected with water before slaughter or slaughtered by unscrupulous traders for profiteering profits,has become a serious damage to the people healthy.The traditional WIM detection methods(sensory detection method,ultrasonic testing method and near infrared spectroscopy method)have defects.Bioelectrical impedance spectroscopy(BIS)can accurately reflect the variation of the conduction frequency characteristics caused by the watered fresh meat.Therefore,this thesis exploratively designs a WIM detection system based on BIS measurment.And this thesis focuses on the data processing methods such as FIR digital filtering,identification of WIM and so on.The main researches include:(1)The WIM detection system is designed based on BIS measuring principle.And the control core of the system is the FPGA chip,EP4CE15F17C8.The chip controls the AD9744 to generate multi-frequency sine wave(Multisine)excitation signal and controls the AD9248 to sample the excitation and response signals synchronously.The sampling signals are transmitted to the host computer by USB after FIR digital filtering.After the signals processed by FFT,we can get 2048 points’ BIS amplitude frequency characteristics and phase frequency characteristics which fundamental frequency is 16kHz and frequency range is 16kHz-1024kHz.(2)The FIR digital filter is designed based on FPGA.First,the general formula of the FIR digital filter is optimized according to the distributed algorithm(DA).Second,the filter coefficients are extracted by using FDATool.Then,the top-level module,address module,look-up table module and shift add module are designed for filtering by using Quartus Ⅱ software,and the correctness of the design is verified through waveform simulation by using Modelsim software.Finally,the detection system is calibrated by using the BIS maesured values and the standered values of the pure resistance and the three components.The calibration amplitude error is within 1.2%,and the calibration phase error is within 0.4°.(3)The identification of WIM and the identification of the meat freshness are realised.First,the BIS of fresh meat(pork,beef,lamb)before and after water injection was measured by self-made detector,meanwhile,the standard impedance of the fresh meat before and after water injection was mesured by the standard impedance instrument.To identify the WIM,we establish the correction model of the BIS and the standard impedance value for the calibration set by using PLS,and the same as the forecast set.The recognition rate of the WIM is 100%.Second,we measure the BIS for the fresh meat every 30 min by using self-made detector and the time lasts 48h.To distinguish the meat freshness,we establish the correction model of the BIS and the time for the calibration set by using PLS and the same as the forecast set.The accuracy of the meat freshness distinction is 100%.This thesis verifies the feasibility of WIM identification based on BIS measurment technology and lays the theoretical and practical foundation for the next step to realise portable WIM detector.