The Study On Real-time Float Motion Measurement System

The six motional parameters of float, such as Pitch, Yaw, Roll, Sway, Surge and Heave, are very important for the research of ocean engineering. However, ruler, angle gyroscope and the light oscillograph are usually used to measure motion in traditional methods. These methods all rely on manual work, so they can't meet the requirement of high precision and waste lots of resources. Untouchable measurement system is based on machine vision and uses double CCD cameras to capture images and to reconstruct the coordinates by using results obtained from the calibration process. And then the 6-DOF of the floating body is decomposed. It does not disturb movement of the floating object and can gains high precision.The specific application of the 6-DOF system with the background of real-time measurement is studied in this paper.Firstly, the research and application of computer vision and image processing algorithm is introduced in detail. The part of arithmetic mostly involves image preprocessing, automatic selection of threshold value, characteristic extraction, calibration, stereo matching, 3-D reconstruction, and so on. Secondly, system software is designed by using VC 6.0 platform and the MIL^TM Library provided by MATROX Company with METEORⅡ/Digital frame grabber. Finally, lots of experiments are carried out aiming at the float movement measurement using the wave-making machine and the measurement precision of the system is analyzed and validated.The paper builds a new platform to improve the image resolution and accuracy, not only resolves the problem of two CCD's asynchronous triggering and synchronous snap, but also realizes real-time process at a rate of 20 frames/s and full-vision measurement. At the same time, the paper resolves several key problems relating to the specific application condition and real-time measurement, finally lots of experiments are carried out to prove the reliability of the system. The results show that the system indeed has high precision and meets the technical requirements of project application and scientific research.