The Research Of Measuring Instruments For Angle In Spatial Polar Coordinate System

The article introduces the way of measuring spatial angle of hole in sphere objects in polar coordinate system .The method is :there are two perpendicular axes whose distance are controlled ,one is the axis of work table, the other is fixed with a microscope for aiming. The turning angles of axes which are recorded by the raster determine the spatial angle of the hole when the microscope fixes on the hole, as well as CCD video is used to get the photos of holes. The center of hole for aiming is gotten through the digital image processing. This paper develops the instruments to realize it, the main contents are as follows:1. According to the design, we decided the main parts of the mechanical system, the rasters are used in closed loop in order to improve the precision. The control system is divided into two levels, in low level the RS232 chip is used to control the devices such as electromotor and lamp-house etc,other tasks such as data collect and process are realized by computer in high level, the two levels are connected through RS232 which makes it easier for maintenance. The main components of microscope are CCD video lamp-house and CCD camera lens, we selected the CCD video and analysed its way of aiming,introduced a new high power white lamp-house which used four circle arrays diodes controlled by single switch, determined the basic parameters of CCD camera lens and selected the lens. The software of instruments consists of these parts:image collect module which sets the parameters and functions of CG200 chip;digital image process module which can process ".bmp" files in windows and use edge-find arithmetic to find the center of hole for automaticaiming;hole measuring module which sets the parameters of measuring and the output of results; software controlling module which resolve the communication of computer and sets the controlling word. At last ,the uncertainty of instruments is analysed.2. With the principle of monomial measuring,we get the values of key parameters,which are used for calculating the uncertainty of the instruments, we also produce a standard workpiece to validate the uncertainty and rectify system error.The instruments can measure the spatial angle of hole with high efficiency and precision,which resolve the problem of position-measuring of hole in our factory.it is also valuable for other similar situations such as optical measurement of micro-dimension structure or components.