Research And Design Of Grating Digital Display Device Based On FPGA

Grating measure technology based on output signal of grating displacement sensor, research displacement amount and movement direction of the object. The paper takes 50 lines/mm general grating for example, uses carrier modulation and phase-lockded multi-frequency subdivision of combinational program to achieve larger displacement tracking speed while larger resolution, and solves the common phenomenon which the resolution increases and displacement tracking speed reduces arises when fractionize signal of grating sensor. Research the mathematical relationship of maximum displacement tracking speed and resolution in synchronization range and the cut-off frequency of phase-lockded multi-frequency subdivision, as a basis for research and design of grating digital devices.The paper introduces development of grating displacement sensor, composition theory of grating, mechanism and characteristics of moirésignal, characteristics of the grating output signal and measurement principle. Discuss and compare the five representative kinds of signal subdivision. Discuss in detail the basic components, working principle and parameter settings of phase-lockded multi-frequency subdivision. Analyse and discuss mathematical principles of carrier modulation circuit and phase-lockded multi-frequency subdivision circui. Using Matlab and QuartusⅡsoftware models and simulates the carrier modulation circuit and phase-lockded multi-frequency subdivision circuit; verify its feasibility and correctness.Select high-speed, high slew rate, high-bandwidth devices according to the signal. Using PSpice software analyses and simulates error amplifier, carrier modulation processing, summation processing, plastic processing and other hardware circuitry to ensure that the signal without distortion. Using the Verilog language and digital chip FPGA achieves ALTPLL generator module, phase-lockded multi-frequency subdivision module, timer module, multi-frequency grating signal counter module, N multi-frequency carrier counter module, subtraction and identified direction module, displacement accumulation and multiplication module, transcoding and display module and so on.While taking the advantage of FPGA and digital-analog converter chip develop analog signal source of grating.When uses the proposed subdivision method to design grating measurement and control system, set the parameter of center frequency, M, K, N to meet different design requirements, the system can get easily optimized parameters and provides a strong mathematical basis for the grating system design. Phase-lockded multi-frequency circuit is achieved in a digital chip which completes the integrated and digitized design, improves stability of the system, gives the specific parameters to achieve the system, has some practical value.