Research on thermistor signal conditioning circuit based on genetic algorithm-BP neural network

It is an important method to detect ocean turbulence by using rapid temperature gradient change, and the accuracy of temperature measurement is an important factor affecting the quality of turbulence measurement. However, the current turbulence temperature sensor is a FP07 thermistor with negative temperature coefficient, which is a nonlinear element and affects the quality of turbulence observation. Faced with this problem, this paper proposes a low-cost two-stage linearization scheme based on thermistor temperature sensing. The first stage is a signal analog conditioning circuit based on operational amplifier, which is used to output the voltage signal and perform the first-stage linear amplification. In the second stage, the two-stage nonlinear compensation of BP neural network based on genetic algorithm optimization is used to make up for the shortcomings of the nonlinear output of the thermistor furtherly. The verification shows that the linearizer realized by the method in this paper has good linearity and accuracy in the temperature range of-2 °C -32 °C, up to 0.005 °C accuracy range. Compared with the standard BP network and the existing linearization method, the results are obviously better, which proves the feasibility and superiority of the proposed method in the linearization of the thermistor.

I. Introduction

Turbulent mixing plays an extremely important role in the process of ocean energy and material exchange. It is the source power of ocean thermohaline circulation and one of the core research directions of physical oceans. The observation of turbulence depends on the development of ocean turbulence observation instruments. At present, domestic turbulence instruments are mainly equipped with shear sensors, which are easily affected by instrument vibration and the observation accuracy is limited. Through the study of the formation and evolution mechanism of ocean turbulence, a turbulence observation method using rapid temperature gradient change is proposed [1]. The rapid temperature sensor senses the temperature fluctuation of seawater temperature in micro-scale structure by measuring the heat dissipation rate of seawater, and indirectly measures the turbulent kinetic energy dissipation rate. As we all know, thermistor has the advantages of high sensitivity, fast response, long life and low cost, and has become the best choice for ocean turbulence measurement.