Research On One-Dimensional Laser Displacemennt Sensor Based On FPGA

With the development of automotives, electronics, semiconductors/IC, metalprocessing, food manufacturing, thin-film manufacturing and other industries, laserdisplacement sensor based on triangulation has been widely used. It has manyadvantages such as simple structure, convenient operation, high-speed measurement,high precision and so on. The development of laser displacement sensors based ontriangulation is not yet mature, it still needs further study.The paper introduces the principle, optical system and hardware circuit designsystem of the laser displacement sensors based on triangulation. It analyses theinfluence factors on the accuracy of sensor. The main work is as follows:1. Laser triangulation displacement sensor system is designed based on FPGA. Theoptical path of oblique and straight incidence is analysed. The parameters of straightincidence are calculated. The paper deduces the Scheimpflug conditions and introducesevery factor that needs to be considered in system on choosing its hardware.2. Signal acquisition, data processing and controlling system is designed based onFPGA. According to the different requirements of the power system, the power schemeis designed. the CCD circuit and the CCD driving circuit are implemented to make CCDwork properly to collect the light intensity information. Data acquisition and processingare implemented by the FPGA controlling and its configuration circuit.3. The system requires logical driving. The paper introduces the flow of FPGAdesign based on Verilog HDL. Phase-locked loop, CCD driving logic, data acquisitionlogic and FIFO data buffer logic are designed by Verilog HDL.4. The paper qualitatively analyses system error sources and the measurementsneeded to reduce the errors. Positioning algorithm is accomplished by hardware logic,which includes centroid algorithm, weighted centroid threshold algorithm and squaredweighted centroid algorithm. Fitting curves are fitted by the expericment data. Themeasurement curves are obtained by inverse algorithm and logic design, which canaccomplish the goal of measurement. In experiment， measuring range:3.5mm.Resolution:4μm The highest error:10μm.