Research And Realization Of New Low-frequency Mechanical Spectrometer Based On The Cortex-M3

The low-frequency mechanical spectrometer is one of the most significant apparatus,which aims to research the internal friction of solid materials.The existing low-frequency mechanical spectrometer mostly adopts the centralized control system model combining the industrial personal computer and data acquisition card,and uses the FFT method to calculate the phase difference.The system model contains several problems on different aspects.For example,the system model has some problems about debugging and maintenance,the system real-time is not restricted,the calculation precision is poor,and this model have high production cost.Based on this,this dissertation proposes and designs a new high-performance and low-frequency mechanical spectrometer basing on the Cortex-M3 processor.The main contents of this paper are following:(1)A method of all-phase FFT spectrum analysis is adopted to calculate the phase difference and analyses the theory about the all-phase FFT spectrum theory.The article carries out the theoretical comparison between the traditional FFT and all-phase FFT,basing on the MATLAB simulation experiment.The results verify that the all-phase FFT has high precision phase measurement performance.(2)The mechanical structure of the low-frequency mechanical spectrometer is analyzed and designed.It is pointed out that the vertical accuracy of the inverted torsion in the system directly affects the measurement accuracy of the material internal friction in the mechanical system of low-frequency mechanical spectrometer.Material samples are loaded in a special mechanical device,which adopts precision adjustable fixture position.The structures and sizes of various parts have been designed in detail.Moreover,the three-dimensional named Pro E,has been applied to establish different three-dimensional modeling in all different parts.(3)A control system has been established,using the Cortex-M3 processor as the main control unit.The control system contains several key modules,such as signal generator module,photo voltaic cell stepper motor control module,dual-channel signal acquisition module and temperature control module.The performance of all the modules has been analyzed and designed in detail.The C programming language is applied to compile the corresponding subroutine.It also designs and realizes the issue of sine signal and the acquisition function of dual-channel signal.(4)C sharp(C #)language is used to design the host computer graphic display interface,realizing data acquisition graphical display.Low-frequency mechanical spectrometer test system was built as experimental platform.In the process of experiment,the internal friction of the material sample was measured in a different temperature environment.Afterwards,combining with the analysis of the experimental data.Ultimately,the curve of materialsconsumed with temperature diversification has been described,which is also called the friction-temperature spectrum.The system adopts the distributed control system combining the host computer and the Cortex-M3 processor.The distributed control system is replaced by the centralized control.The space of the software and hardware is increased and optimized.It facilitates the system to debug and maintain.Besides,the paper applies the all-phase FFT spectral analysis method to calculate phase difference.This method can overcome the shortcomings about traditional FFT method.It can realize real time,reduce the calculated quantity and enhance the anti-interference.The system scheme prefects the real time performance and reliability about the system and improves the calculation accuracy about the low-frequency mechanical spectrometer effectively.It lays a foundation for system optimization in the future.