| With the development of pipe-laying technology of deep-sea,pipe-laying vessels play a key role in pipe-laying and equipment transportation.HYSY201 is the first 3000m deep-water dynamic positioning pipe-laying vessel designed in China.HYSY201 was upgraded to improve its ability.In this paper,the results of field measurement at sea and the numerical simulation are compared about HYSY201,which can be used for technical guide on practical offshore operations.This paper presents a method about field measurement of pipe-laying vessels:using X-band wave radar to obtain data of current and wave;using GPS/INS to monitor 6DOFs of barge motions;using K-Pos to record the propellers.It was the first time to test the dynamic positioning ability of upgraded HYSY201 at sea,the performance and responses of HYSY201 was measured.We establish the equations of motion and the sea environment loading model about dynamic positioning pipe-laying vessel.The PID algorithm and the thrust distribution algorithm are used to control the vessel for positioning at origin or keeping track.Commercial software SESAM is used to analyse the wind current loading coefficient and frequency response of hydrodynamic force about HYSY201.The dynamic positioning responses of HYSY201 on standby and on pipe-laying are simulated using the PID control algorithm.The field measured results are compared with those predicted.sensitivity analysis is studied of HYSY201 on standby.The sensitivity analysis results show wave direction has a great influence on dynamic positioning response.The positioning results get worst while wave direction is 90 deg.The motions of each degree of freedom and thrust have positive proportion with wave height and peak period.Wave height and peak period have different effects at motions when wave direction changes.Field measurement results show the rationality and accuracy of this method,which could be widely used in field measurement.The field measured results are compared with those predicted.Fair well agreement is reached,which means PID algorithm can simulate the response of dynamic positioning well.The research can be used for technical guide on practical offshore operations. |
