Research And Implementation Of The Embedded Optical Fiber Displacement Sensor And Signal Processing Circuit

With the rapid development of industrial technology, the higher precision and the more method are demanded for the measurement of micro displacement. At the meantime, with the development of sensing technology of optic fiber, fiber optic sensor is applied to many occasions owing to its incomparable advantage now. On the basis of looking up the concerned technical literature and data, especially the documents of measurement for micro displacement and embedded intensity modulated optical fiber displacement sensor, the paper introduces the design of a mini-type embedded intensity modulated optical fiber displacement sensor for micro displacement measurement, and describes the implementation of every functional module of this sensor, including probe, light source modulating and driving circuit, optoelectronic receiving circuit, weak signal process circuit, micro controller unit and relevant software design. In the sensor design, on the purpose of reducing error and eliminating common interference such as the influence of the external environment, the reflection type probe with an additional reflecting optic fiber used as reference optical path is adopted. Besides the probe design, whether the whole system can work normally and achieve the precision depends on the subsequent signal processing circuit. In this design, the signal processing circuit is composed of several functional modules, such as preamplification, bandpass filter, phase sensitive detection, low pass filter etc, which are implemented by hardware in order to improve the precision and stability of the sensor. On the other hand, to reducing the inherent shortcomings of the hardware circuit, such as difficult to change and large cost, a high-performance micro-controller ADuC812 is adopted. Two-path analog signals coming from the sensor are inputted to ADuC812 and then processed through software approach, including functions of signal division,linearization and compensation etc. Through above-mentioned process, the software shares some functions of hardware, so the flexibility of sensor is improved and the cost is reduced. The sensor also possesses some intelligent functions of self-check, self-correction and so on. To test the measurement effect of this designed sensor, the experiment is done and the data analysis is provided. The result indicates this sensor reaches the designed requirement.