The Development Of A Precision Laser Diameter Measurement Based On FPGA

Measurement is a necessary course in the production of the mechanical industry, it is an important basis of quality control that relate to the improvement of product quality and development of equipment manufacturing. In the field of the measurement of mechanical products, size measurement is the most important and popular content. And in size measurement, the diameter measurement of the axial parts is applied the most, the fields it involves the most widely also. For example the lathe screw, lead rail, crankshaft, trim of the steering valve, etc. The precision of the most common lathe screw in20to50μm or so, even the trim of the steering valve is controlled less than7～10μm. Thus, the diameter measurement of the axial parts is not only common, and also required higher measure precision than other parts.Because of its low precision and influence by human, the traditional way to measure can't meet the high precision requirements of axial parts diameter measurement. With the development of non-contact measurement technology, especially the appears of the laser measurement technology, combined with CCD application technology and EDA technology, size measurement is coming to a new time, laser diameter gauge is more and more applied in the field of diameter measurement of axial parts.This paper first planed the laser diameter gauge, and layout according to the two direction of mechanism and the hardware circuit. It build the optical measuring mechanical structure, and designed the relevant basic circuit of measuring.This paper focuses on the diameter measurement method based on FPGA, by the use of hardware description language Verilog HDL, it accomplished the module design of process from the CCD drive to data acquisition, processing, transformation and display. Firstly using CCD driver module to realize CCD video signal output normally, through the signal acquisition and processing module to control the function of outer circuit, and send the the result to processing and calculating, the obtained results then sent into display module after a series of process of data cache and conversion, and controlled the measuring results to display on the LCD ultimately.After the completion of the design, it debugged each part of the laser diameter gauge through a series of experiments, and verify the precision and reliability of the laser caliper gauge through standard sample measuring.