Study On Underwater 3D Structured Light Measurement And Its Application In Vision Guidance And Positioning

In recent years, the development and exploration of the ocean has promoted the underwater robot. As the diversity of the complexity of the underwater environment and underwater tasks, underwater 3D measurement of high precision plays an important role in visual guidance and localization. The key technology of underwater 3D structured light measurement and its application in vision guidance and positioning are studied. Underwater 3D structured light system is used for vision guidance and a platform for underwater autonomous task is built; and the corresponding underwater model of three-dimensional measuring mathematical is established, the camera parameters and system parameters are calibrated respectively; an effective compensation is used to the underwater refraction so that the land calibration result can be used to realize the underwater measurement. The relationship of the manipulator and the structured light system is calibrated.With the help of the identification and of specific target autonomous task is realized.The 3D structure light detection system both on land and underwater is analyzed. According to the relationship among the camera, laser plane and the measured object, the mathematical model of three-dimensional measuring system is established. The model contains the camera imaging optical path and laser plane refraction.The camera parameters and structure light system parameters are calibrated respectively. Z. Zhang’s method is used in calibration of the camera, the target is a paper of chessboard; then with the help of the same target, the relationship between the camera coordinate system and vibrating mirror coordinate system is calibrated, by now the calibration of the whole system is complete.An improved method for refractive compensation for underwater 3D structured light system is proposed, which not only overcomes the influence of light refraction, but also reduces the influence of glass refraction. The refracted laser plane is calculated again, the offset of the camera imaging due to refraction is compensated, which makes the land calibration parameters suitable for underwater measurement.Through the calibration of vision system and the manipulator coordinate system, vision guidance is realized.The measured data is analyzed, Identification and localization of the target object is realized.According to the requirements a series of experiments is conducted. Experiment of OpenCV calibration method shows smaller error; measurement result of standard shape shows high accuracy of structured light system; accuracy experiments is carry out by the recognition of different underwater object, it shows that the 3D data provided by the measurement system can meet the accuracy of the visual guidance and positioning.