Design Of Steel Tape Calibration Platform Based On CCD And Grating Metrology

This paper is oriented on research of measurement and control technology of a automatic steel tape calibration platform at 5m scale. The main work is listed as following:1, Setting the top design of the platform according to JJG4-1999 steel tape calibration procedures, including functional modules and structure design. A movable CCD and 8 solid cameras and grating system are used as standard inputs for the whole system, dual orbit solution is taken to support 3 calibration modes. The hardware module and software development environment are also introduced.2, Analyzing several methods for grating signal subdivision and then deeply discuss a signal division algorithm based on mutual compensation functions. Proposing a method based on signal division and pulse counting which greatly improves the speed of measurement. The maximum speed is only limited by the maximum allowing speed of readhead. Constructing the grating measurement system, including signal processing circuit and 16bits dual channel sampling circuit with USB interface. Both simulation and experiments indicate that the relative error of subdivision measurement is less than 1‰, which can satisfy the demanded uncertainty of 0.01mm.3, Constructing image acquiring system, including camera selection and image processing program. The software developed based on LabVIEW can manually or automatically locate the target line. According to the common type of steel tapes and the image processing experiments on actual pictures, the majority of steel tapes can be calibrated.4, Developing the operating software based on LabVIEW to help operators finish the calibration work with high efficiency. Describing details about the operating procedure of the software. A report in word format would be created automatically to facilitate the file record and transmission.