Development Of Bearing Hole Pose Measurement Of Propulsion Shafting System

The quality of ship shafting alignment is related to the long-term normal operation of shafting. In shafting installation process, a misalignment of 0.0002 radian could reduce the load capacity of a bearing by 40 percent. To make the bearing load distribution more uniform, reduce bearing eccentric wear, the control precision of the bearing angle must reach 0.03 mrad.Various methods of measuring curve of shafting have been analyzed in this paper, a technical proposal of bearing hole pose measurement has been provided to guide the shaft bearing conform to the deflection curve with high precision installation. Based on the non diffracting beam datum,put the probe into the bearing hole, calculate the pose of bear hole by measuring the position of head face and end face of probe and compare with the non diffraction optical reference.A detailed design of bearing hole pose measurement system has been provided in this paper, including the optical and mechanical structure. The components within the probe has been selected and manufacturing the probe. The software included the functions about the measurement data collection, preservation, evaluation, digital output is written by VC6.0.The image collected by probe has been analyzed, the special algorithm of seeking concentric rings of the measurement scheme has been developed. The initial center is get by gravity method with threshold and use the extremum method to obtain the concentric rings of image. The breakpoint has been Skip over by the method of circular scan and at last the concentric circle center with subpixel accuracy has been get by rough and fine Hough transformation. The reliability of the algorithm has been test by experiment.The calibration method of all parameters in the probe has been provided. The transformation matrix which transform the coordinates of the center to the pose of the probe has been calculated by calibration experiment.Through the experiment,the experimental scheme is feasible and concentric circle center has subpixel accuracy. The measurement accuracy of probe when it take parallel movement reached 0.05 mrad,basically meet the design requirements.