Research On Heel/Roll Reduction Control Methods In Ship Turning

With the consumption of land resources,countries have paid more and more attention to the development and utilization of ocean resources.The density of ships on the sea has increased greatly,which has put forward higher requirements for ship maneuverability Turning ability is an important part of the maneuverability of the ship,reflecting the performance of the ship to change its state of motion,and is closely related to the safety of the ship.However,due to the rolling and heeling during the ship's turning process,the seakeeping problem needs to be considered in the turning maneuvering process.For ships turning at high rudder angles,large heel are generated even in calm water.If it is disturbed by the waves at this time,it will cause a large roll on the basis of the heel,which will seriously affect the normal work of the ship's personnel and threaten the safety of the ship.Therefore,it has important practical significance and application value for improving the safety of ship turning maneuvering to study the seakeeping problem and use the existing anti-rolling control devices to design a reasonable control strategy to reduce the heel and roll during ship's turning process.Firstly,a multi-purpose naval ship is taken as the simulation research object,and its four-degree-of-freedom nonlinear coupled motion model is established using MMG method.The effects of initial sailing speed,turning rudder angle and rudder rate on the ship's turning characteristics are studied by the turning motion simulation in calm water.The applicability of the established model is verified.Through further simulation and comparison analysis,the characteristics of ship's turning motion under sea wave disturbance are obtained,which lays a foundation for subsequent research.Secondly,the hell/roll reduction control method of fin stabilizers in the high-speed turning with large rudder angle is studied.Through the simulation analysis of the ship's turning motion under different static fin angles,it is found that the fin stabilizer has the opposite effect on the turning outward heel and the turning diameter.On this basis,the two conditions of confined water and open water turning are divided,and the principle of fin stabilizer control considering the fin angle speed adjustment during ship turning is given.The control system model of fin heel/roll reduction is established through analysis.Aiming at the characteristics of disturbance,uncertainty and nonlinearity of the system,a fin heel/shake reduction adaptive robust controller based on L2 gain is designed.The simulation shows that the designed controller has good robustness to the uncertainty caused by the speed reduction of turning and the internal and external interference.On this basis,the nonlinear disturbance observer is used to realize the observation estimation of system uncertainty and interference,and the stability of the control system is verified theoretically.The simulation shows that the addition of disturbance compensation improves the control performance of the system,which achieves better control effect with smaller fin movements.Aiming at the influence of sea wave disturbance on the ship's turning characteristics,a heel compensation based control strategy of fin stabilizer during ship turns is proposed.The simulation shows that the proposed strategy can also effectively reduce the heel and roll during ship turns.However,its anti-rolling effect is not as good as the first two control methods.Thirdly,the method of rudder roll stabilization control in the high-speed turning with large rudder angle is studied.By superimposing the dynamic rudder angles of different amplitudes and frequencies on the static rudder angle,it is found that the dynamic rudder motion can cause the ship to make a certain degree of rolling on the basis of the calm water outward heel without much affecting the ship's rotation characteristics.Considering that the roll reduction ability can be reflected by the forced roll ability,the principle of rudder roll reduction control during ship turning motion is proposed through further analysis.On this basis,the model of the turning rudder roll stabilization control system is established.For the nonlinear system with interference and uncertainty,a backstepping based adaptive sliding mode rudder roll stabilization controller is designed.The simulation shows that the designed controller can effectively reduce the roll motion caused by sea waves during ship turns Aiming at the problem that the turning rudder roll stabilization control can not reduce the initial inward heel,a changing rudder rate turning rudder roll stabilization control strategy with low rudder rate for rudder deflection and high rudder rate for roll reduction is proposed on the basis of considering the influence of the rudder rate on the turning characteristics.The effectiveness of the proposed method is verified by simulation.However,since the rudder speed has the opposite effect on the initial inward and advance,using the low rudder speed to reduce the initial turning inward heel of the ship will also increase the advanceAfter that,the method of the integrated rudder/fin heel/roll control in the high-speed turning with large rudder angle is studied.Since both the fins and rudders can reduce the roll motion caused by sea waves during ship turns,this inevitably leads to the problem of integrated rudder/fin control during ship turning process.Considering the influence of rudder and fin stabilizer on the ship's turning characteristics,the integrated control methods of fin heel reduction+rudder roll reduction and fin heel/roll reduction+rudder roll reduction are proposed.The simulation shows that the two control methods can effectively reduce the heel and roll during the ship's turning process,and the fin heel/roll reduction+rudder roll reduction integrated control is more effective.Compared with the separate fin heel/roll reduction control and rudder roll reduction control,the integrated rudder/fin heel/roll reduction control effectively reduces the control action of the fin stabilizer and rudder while improving the anti-rolling effect,and has better control effect.Finally,the proposed control methods and strategies are verified by self-propelled ship model test.Under the support of the project funds,the scaled self-propelled model of a certain type of ship was built.The design of the hardware system and software system of the self-propelled model is given,where the hardware system is divided into the shore-based control subsystem and the ship-borne control subsystem.After completing the on-land joint adjustment of the self-propelled model system,the self-propulsion model test was carried out in accordance with the test program.On the basis of completing the free roll decay test,forced rolling test during straight line navigation,and turning motion in calm water,the subsequent heel/roll reduction control test procedure was optimized.The heel/roll reduction control using fin,rudder and integrated rudder/fin in joint straight line navigation and turning conditions were carried out.The test results show that the integrated rudder/fin control has the best roll reduction effect under both straight line navigation and turning conditions,while the anti-rolling effect of the separate rudder roll stabilization control is relatively worst.The test results is consistent with the theoretical simulation results.However,the effect of turning fin heel reduction control effect was found to be poor during the test,which is far below expectations,but the overall trend was basically consistent with the theoretical simulation results.Although there are deficiencies,the initial self-propelled model test has basically achieved the expected results,and preliminarily verifies the results of the previous theoretical simulation research.