Research And Designing Of High-precision Temperature Control System For FOG

The Fiber Optical Gyroscope is a kind of optical sensor basing on the effect of sagnac which uses solid-state all-optical structure to measure the angular velocity. Compared with the traditional mechanical gyroscope rotor, the Fiber Optical Gyroscope has solid-state, no mechanical moving parts, large dynamic range, high reliability, simple structure and can start instantly. All these advantages make it gradually become an extremely competitive and new gyroscope. However, the FOG temperature is an important issue to be resolved in the process of development and engineering Its performance of temperature likes its main optical fiber gyro in the device performance greatly affected by temperature. In FOG fiber optic ring, temperature gradient effect exist. It generates heat caused by the noise of non-reciprocity. FOG circuit noise in the case of different temperatures will also affect the accuracy of its output; FOG shell structure designing and material selection also has a great influence on the temperature performance of fiber optic gyroscope. To solve this critical problem, it is essential to design a high-precision temperature control system to provide a constant working environment temperature for the FOG. Not only is it effective to guarantee the output accuracy of the FOG, but also it has an important practical significance to improve the precision of the Fiber SINS.The purpose of this paper is to design a set of high-precision FOG temperature control system which is applied on the ships by doing many deep research. The temperature measurement module is one of many important elements of temperature control system. If the control system wants to control the temperature of the controlled object, the error between the setted temperature and the measured temperature is always one of the most important inputs, and then there will be an appropriate control. That is to say, the higher accuracy the temperature measurement module has, the higher precision the temperature control module will be. Therefore, to study how to improve the measurement accuracy of temperature measurement module will have a strong practical application value for achieving a high-precision temperature control system. First of all, there are lots of detailed analysis of the. existing temperature control system about hardware circuits designing, temperature compensation algorithm, control algorithm and some other aspects. Second, in order to solve the problems of large nonlinearity, low sensitivity, low output accuracy and so on which the existing temperature measurement circuits have, designing of the dual current source circuits and research of the Least-squares Fitting Program and the Butterworth Digital Low-pass Filter have been accomplished. And then, the high accuracy temperature measurement module is completed through the combination of hardware circuits and software compensation.As we all know that the temperature measurement module determines the measurement accuracy of the temperature control system. And the temperature control module determines whether the control system could achieve high precision control in accordance with the desired characteristics. At last, in order to achieve high precision temperature control, it is necessary to have high reliable control algorithm and high precision drive circuits. In order to solve the "dead zone" problems which the existing PWM control circuits have, other control circuits which are constituted mainly by MAX1968 have been accomplished to replace it successfully. In order to solve the weak anti-interference problems which the traditional PID control algorithm have, many research of Fuzzy self-tuning PID parameters control algorithm and the combination between the traditional PID control algorithm and the Fuzzy self-tuning PID parameters control algorithm are finished. So that, not only does the combination control algorithm have the advantages of flexible and adaptable, but also it has the advantage of high precision control. Last, the software and hardware designing and debugging of the whole system are successfully completed. And the experimental datas with long time show that temperature measurement accuracy of the whole system can reach to±0.03℃and the control accuracy is more than±0.1℃.