Study On The Method Of Rotation Angle In-plane Measurement On Machine Vsion

Through studying the technology program of the existing typical of in-plane angle measurement method, summed up the defects and deficiencies of various types of measurement method, We propose a method of rotation angle measurement with high precision in machine vision. An area scan CCD camera, imaging lens, and calibration pattern with a spot array make up the measurement device for measuring the rotation angle.The calibration pattern with a spot array is installed at the rotation part, and the CCD camera is set at a certain distance from the rotation components. The coordinates of the spots on the calibration pattern is acquired through the vision image of the calibration pattern captured by the CCD camera. At the initial position of the calibration pattern, the CCD camera is calibrated with the spot array; the mathematical model of distortion error of the CCD camera is built. When the standard lattice plane target turned a certain angle with the tested part, A standard digital image of the standard lattice plane target is captured by the area scan CCD camera, and then the detection algorithm of the position of the points is used to yield the image plane coordinates of the target points. Next, the projection model of the CCD camera is built to modify the errors of lens distortion by calibrating the camera. Then the object plane coordinates of the spot array are acquired. With the transformation equations to yield the rotating angle of the spot array, the rotation angle in-plane of the measured object is obtained.Through simulation and actual measurement experiments, the experiment results show that the measurement device can measure the rotation angle precisely with a noncontact method. The standard deviation of rotation angle measurement is smaller than2arc sec. The measurement device can measure both microangles and large angles.Through the analysis of the entire in-plane angle measurement system, the mathematical error model of the in-plane angle measurement system is establishment, then, detailed analysis of the error sources are made. Through simulation and actual experimental measurements, the Relationships between systematic error and the precision of the measurements method is built, and draw the main systematic error, these is helpful to further improve the precision of the system.