| Frequency modulation continuous wave(FMCW)laser interferometric fiber optic pressure sensor has the advantages of high measurement accuracy,good stability,anti-electromagnetic interference,explosion-proof,flame retardant and so on.It can be used in petrochemical,aerospace and other fields.However,ambient temperature and other factors will lead to measurement errors of FMCW laser interferometric fiber optic pressure sensor.In order to eliminate the influence of temperature on pressure measurement,the temperature characteristics and temperature compensation method of FMCW laser interferometric pressure sensor are studied in this paper.Firstly,this paper analyzes the principle of FMCW laser interferometry and the measurement mechanism of FMCW laser interferometric diaphragm type optical fiber pressure sensor,and uses Solid Works software to simulate the relationship between the diaphragm deformation and pressure;then combined with the structure and material characteristics of the pressure sensor,the influence of temperature on each component of the pressure sensor is analyzed;finally,the temperature characteristics of the pressure sensor are obtained through experiments.Aiming at the temperature drift problem of FMCW laser interferometric fiber optic pressure sensor,two temperature drift compensation methods are proposed.The first method is to use an auxiliary interference chamber to correct the effect of temperature on the cavity length of the pressure sensor by measuring the effect of temperature on the length of the auxiliary interference chamber.Firstly,a FMCW laser temperature sensor is made as an auxiliary interference cavity;then the auxiliary interference cavity and the pressure interference cavity are fixed together;finally,the temperature compensation model is established,and the dual-parameter signal acquisition algorithm and temperature compensation algorithm are written to correct the temperature drift of the pressure sensor.The second method is to use a thermocouple that measures the absolute temperature by measuring the absolute temperature to correct for the effect of temperature on the cavity length of the pressure sensor.Firstly,the circuit design of thermocouple temperature measurement module is carried out to realize temperature acquisition;then the temperature compensation circuit is designed based on ARM microprocessor chip(stm32f405);finally,the temperature compensation algorithm is compiled,the temperature drift of the pressure sensor is corrected according to the relationship between the cavity length of the pressure sensor and the temperature,and the host computer software is designed with pyqt5.The temperature compensation system is set up for experimental verification.Experimental results show that after using auxiliary cavity compensation,the measurement effect of temperature on FMCW laser interferometric fiber optic pressure sensor is reduced from 5.928 k Pa/°C to 1.616 k Pa/°C.After using thermocouple compensation,the measurement effect of temperature on FMCW laser interferometric fiber optic pressure sensor is reduced from 5.932 k Pa/°C to 0.872 k Pa/°C.Both temperature compensation methods effectively reduce the measurement compensation of FMCW wave laser interferometric fiber optic pressure sensors. |
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