Research Of Embedded Grating Displacement Measurement System

Grating measurement technology is a high precision measurement technology based on counting the Moire fringes created by the grating moving. And the subdividing of the grating signal is one of the most economical and effective method to improve the precision grade of the measurement technology. This paper systematically introduces the domestic and international status and development tendency of grating measurement technology, analyses the current application status of Moire fringe division scheme in grating measurement. Through comparing the advantage and disadvantage of every scheme, the new software digital subdivision method and real-time direction discrimination theory are showed. To enhance the agility and reliability of the instrument, embedded technology is applied in grating measurement system. Based on the advantage of embedded technology, a design plan of Embedded Grating Displacement Measurement System is finally given.The article introduces the method of hardware design, the establishment of ARM-Linux development environment and the design of systematic software in Linux operation system. The hardware part discusses the design of each circuit, such as differential amplifier circuit, A/D converted circuit, keyboard and display circuit and peripheral interface circuit of processor S3C2410. Through the construction of ARM-Linux development environment, the important role of virtual machine and cross-compiler has been shown. The software design part mainly includes writing hardware drivers, compiling program, loading program and debugging techniques, and the basic flow and main work done by application program is also illustrated.By system debugging, it proves that the new software digital subdivision method and real-time sensing theory are feasible. The grating displacement transducer of 20μm grating pitch adopted in the design can be used to reach subdividing for Moire fringes, and to improve the system resolution to 0.1μm. At last, based on the analysis of the influence of nonorthogonal error, nonequivalent amplitude error, harmonic error and A/D quantization error on system performance, the method of reducing the error and improving the precision of the system is put forward.