Data Acquisition And Processing Technology Of Fiber Fabry-Perot Strain Gauge Integrated With DSP

The strain measurement has become more and more popular in our daily life . It has a lot of applications in material science, mechanics, machine, aeronautics and petrochemistry. The conventional resistance strain sensor has played the key role in short-time strain measuring. However, it also has some disadvantages in some aspects. For example, it must have temperature compensation, and it is not suitable for long-time strain measuring .The fiber optic Fabry-Perot strain sensing is a new strain sensing technology at the end of 1980. Although the overseas and domestic research about the fiber optic Fabry-Perot strain sensing has entered into an in-depth study, a further study on it needs to be carried out urgently. In this paper, after reading a lot of reference books and literature available on Fabry-Perot strain sensing, the author has done a lot of important studies on developing the fiber optic Fabry-Perot strain gauge integrated with DSP on the base of the technology available now. The following are results:The basic measurement principles of EFPI has been discussed firstly, the characteristics of output signal of brand light source and the effects on the output signal of F-P sensor because of the coupling loss were also discussed. Secondly, three wavelength modulation methods of F-P sensor were discussed. Multi-apex method, discrete gap transformation (DGT) and FFT were discussed. DGT was used to modulate the gap of sensor more precisely.Thirdly, features about the output interface method of strain gauge have also been discussed. After discussing the principle of DSP system, the feature and structure of DSP pin and the software development environment like CC, the whole structure of one new strain gauge integrated with DSP was proposed, and the key problems of realizing this gauge were discussed. The four key steps to realize this gauge integrated with DSP were data acquisition, data processing, data display and keyboard control. Clearly, finishing data acquisition and data processing are the two basic and important aspects.In addition, the hardware and software design of data acquisition and processing have been finished and the experiments about them have also been realized to validate the effectiveness of hardware design and software programs. The hardware development included the choice of DSP pin, serial communication between the spectrometer and DSP by using UART, memorizer extending and watching circuit of DSP. Then, the whole programs of strain measurement were aslo finished after knowing a lot of information about this measurement functions.The experiment of force loading and force unloading on sensor has also been realized. In addition, the author finished two continues loading experiments using equivalent intensity beam. Importantly, zero padding was effective for eliminating the periodic flopping of strain changes. Finally, the discussion about the further problems to be solved in this gauge was finished and the author inferred that the USB interface between DSP and spectrometer and demodulation method about the F-P sensor are the two role parts, which affect the speed of DSP performance. Certainly, modifying and optimizing the program are the other two aspects affecting the speed of measuring.