Research On The Theory And Experiment Of Outside Diameter Precision Measurement Method Based On Laser Scanning

The laser-scanning outside diameter precision measurement uses laser as the basis light beam, scans the work piece by the uniform scanning light which is generated through the reflection of multi-faceted prism that is rotating in high speed and the distortion of the k-θLens, and measures accurately the scanned time of piece to obtain the parameter of diameter. During the measuring, all kinds of error factors are fully considered, and the deviations which is generated in the measuring process, are amended and compensated through valid measures. Because of the characteristics of high-speed, non-contact and high-precision, the laser-scanning measurement fits for the measurement of those pieces such as hot pieces, soft pieces, pieces with moving and pieces with vibration. This method can be applied to precision manufacture, on-line detection and quality controlling in machinery manufacture, aerospace and fields, so it has comprehensive prospects.This paper elaborated the design and implementation of the laser-scanning outside diameter sophisticated measurement system in detail, designed the system's mechanical structure, optical system and control system, elaborated the key technique which were related in the system design in detail, analyses and design many key-issues in detail, such as the laser alignment, multi-faceted prism laser-scanning, k-θlens design and the optical signal processing.The paper analyses the main error sources affecting the precision of system in the form of special theme, that includes in geometric deviation of scanning prism, scanning speed fluctuation, edge detecting deviation, laser intensity changes, installation deviation of optical parts and other influence such as the environmental dust and atmospheric turbulence, and the corresponding compensation measures are given, and then it is affirmed that the compensation measures are correct and effective by digital simulation and actual measurement. To improve the precise, the paper uses BP neural network algorithm to train the actual data measured and establish the mathematical model of precision calibration considering the nonlinearity within the measuring range, and the trained calibration model is verified by the typical standard samples. The results prove that the calibration model are correct and effective, and meet the requirements of the real-time and measurement accuracy. Besides, the paper simply presentes the method of the system fault detecting and diagnosis based on operating parameters of system monitored, analyses the main monitoring parameters and changing ranges of system, gives some handling methods such as the judgment of the fault location, the fault warning and so on.The paper mainly researches the theory and the related technologies which were used in outside diameter precise measurement of laser scanning by uniform speed-scanning of multi-faceted prism, deeply researchs and practices the key technologies of the optical measurement system and major factors which affect the precision of measurement, all the work laid the foundation for the measure instrument's industrial design and development.