Research And Design Of The Inclination Angle Measuring System Based On PSD And FPGA

With the sensor technology,laser technology,precise device technology, electronic technology and microprogramming technology's advancement,society at home and abroad becomes more and more demanding to the measuring technology for inclination angle.Gradually the inclination angle measuring technology develops in the mode of high integration,real-time online,complete-function,high reliability,high speed and precision,industrial dynamics etc.it will have good applying prospect in the field of construction projects,space technology,aeronautics and astronautics,machine work etc.,and also provides a reference way of improving the automational and intelligentized level in the human work and life.This paper firstly introduces development history of the inclination angle measuring at home and abroad,research situations and trends also mode,the meaning of research for inclination angle measuring,then elaborates the whole system designing based on the PSD.PSD is a kind device that sensitive to position offset,it is widely applied to many frontier fields like system for distance measurement,sensor-based system, optical communication,system for signal processing etc.because of its features that high responsibility,high resolution,easy to process for signal etc.This paper takes one-dimension PSD for measuring sensor,analyzes from its architecture first,then its principle and characteristics,constructs the whole frame for measuring system.This paper sets up subtle model architecture for the PSD.The PSD is put in a cassette with a 1×10mm rectangle as a narrow cut on its top for the pass of the reflected laser beam from reflecting mirror pasted under the bracket for inducing the inclination,and the rectangle is isolated by optical narrowband filter,so the photosensitive surface of PSD can detect offset from the 0.3mm thin laser beam. Device files indicate that there is approximate linear relation between one output current of PSD and offset of the laser beam at certain range,and this paper models the system relation through the data collected by one of PSD outputs. Also this paper designs current to voltage conversion circuit,low pass filtering circuit,phase conversion circuit to each current,converting the weak current signal to voltage,then anti-interference processing,converting signal for meeting input demand of the A/D module.System takes 14-bit A/D converter device AD779 for designing signal from analog to digital,before that choosing the bigger signal by optional switch circuit after a comparer when the two voltage signals reach stable.The driving timing for this A/D converter device and the LCD displaying is achieved by FPGA.Also this paper makes error analysis and discussion about the whole model that constructed for the system,and designs codes to realize the arithmetic by FPGA at last.At the end of this paper,making a conclusion about the factors that could bring errors and their solutions,and also the outlook of the work for the research of this paper that need to be improved is discussed.