Study On The Key Technique Of New Wave-movement Compensative System For Sealift Ships

The sealift of ships can expand traffic capacity and Adaptability to environmental of harbors. They also can reduce the investment risk of harbors construction and expend endurance ability of modern navy ships. But because the ships would make six degrees of freedom wave movement at sealift, Impact Loads of the crane cargo in Landing are very great, or slipping off the normal Landing spot, even bumping the superstructure. Especially sealift inflammable and explosive materials or fragile materials are more hazardous. As show practices, applying ordinary cranes, the sealift of ships can not carry through in the weather conditions over grade-3 sea conditions. The information about coasting of the world shows that there are about 50% of the time over grade-3 sea conditions, so this research on the key technique of new wave-movement compensative system for sealift ships possess great significance to develop sealift.The research is carried out by means of theory analysis, computer simulation and model test in this thesis. The key problems that have been solved include the new wave motion detection system of sealift ships, the availably integral methods of the measured acceleration, the forecasting technique for revise of integral error and the prediction of ship wave movement, the robot for six degrees of freedom wave compensation of sealift ships.Firstly, the paper founds the detection model of ship wave movement based on gyro-free accelerometers array or based on electronic compass and accelerometer through mathematical modeling and theory derivation, presenting the method to measure ship wave movement by a 3-axis accelerometer and three 2-axis accelerometers or a electronic compass and a 3-axis accelerometer. Their soft and hardware system are designed and founded.Secondly, acceleration data detection experiment system simulating ship movement is founded, and Acceleration data are measured. By the statistical analysis, spectral analysis and simulation analysis of the accelerometers zero drifting and data integration, the solving measures to remove the integral accumulative error of the direct current component, low frequency component, high frequency component and integral constant item is put forth. The effective integration method in time-domain and in frequency–domain of acceleration signal is put forth.Then, by the research and improvement of the frequency spectrum forecasting technique based the integral system of ship wave movement, the integral errors are maximally corrected and the wave movement of sealift ships is successful forecasted.Next, the experimental model of ship sealift wave movement is founded, and the measurement and data pressing are carried out, that test the detection system of ship wave movement and the method of data processing. According to similitude criteria, the wave movement data of mother sealift ships are gained, that supports for the research of the six degrees of freedom parallel robot for the compensation of sealift ships wave movementFinally, based on the results of the experiment of ship sealift wave movement, by the study to inverse pose solutions modeling, kinematics modeling, and dynamic modeling for normal pose solutions modeling for six degrees of freedom parallel robot, the six degrees of freedom parallel robot for the wave movement compensation of sealift ships is optimally designed. By designing control signal system and hydraulic pressure system of the wave compensation device for sealift ships and simulating on the wave movement compensation of mother sealift ships, the practical disposing system for the wave compensation device for sealift ship is put forth.By the research on key techniques of the wave movement compensation for sealift ships, it is founded that the wave movement measurement technique of sealift ships based on gyro-free accelerometers array or based on electronic compass and accelerometer, the integral technique achieving the available integral for real-time system of wave movement compensation of sealift ships and the improved forecasting technique based on the frequency spectrum correcting the integral errors and achieving long time forecasting, the six degrees of freedom wave movement compensation technique which can compensate for six degrees of freedom wave movement of sealift ships by installing on common crane. The results of the research provide a significant reference for the design and manufacture of the wave compensation system for sealift ships.