Research On Wave Compensation Control Of Floating Crane Based On MPC

When the floating crane is subjected to the sea waves and sea wind during ocean-going construction,seabed salvage,and sea cargo barge,it will produce huge pitch,roll,bow,surge,sway,heave and their coupled motions,which will seriously affect the stability,operation efficiency and safety of offshore operations.Therefore,it is very important to suppress the wave disturbance and carry out the wave compensation of the floating crane.The study of the wave compensation control system has important theoretical significance and application value.This thesis takes the wave compensation system for offshore hanging objects as the research goal,and studies the related issues of the compensation system for offshore floating cranes.The basic viewpoints and innovations of the thesis can be summarized as the following aspects:First,the wave has a very important influence on the stability of the floating crane system,so the accuracy of the wave model will play a decisive role in the floating crane compensation system.Therefore,in this thesis,the wave waveform function corresponding to the sea conditions is established by using the pop function considering different sea conditions,and the wave model under different sea conditions is used as the incentive to establish the motion model of the ship in the wave,and the pitch,roll and heave waveforms of the ship when the Angle between the ship and the wave is 30 degrees are obtained.On this basis,the motion characteristics of the offshore floating crane system under wave disturbance are analyzed.The simulation results show the wave waveform and frequency spectrum under the third,fourth,fifth and sixth sea states,and give the heave displacement,roll angle and pitch angle of the ship under the disturbance of the third to sixth sea states,which further obtain the heave displacement movement of the floating crane.Second,a new active compensation scheme is proposed for the three-degree-of-freedom wave compensation scheme of rope traction combined with the wave compensation system.Considering that the dynamic model and kinematic model of the compensation device can comprehensively reflect the movement of the lifting process,the forward kinematic model of the lifting object and the dynamic model of the hanging plate stabilizing mechanism are constructed.The mechanism and influence relationship between the change of wire rope length and the position and posture of the hanging plate and the change of wire rope tension.Through the simulation analysis,it is proved that the geometrical physical parameters are regarded as the numerical simulation parameters for the non-smooth dynamic model,and the dynamic experiment analysis is carried out on the simulation experiment system of the lifting mechanism.Thirdly,aiming at the control problems of the offshore crane leveling system and floating crane system,the displacement compensation strategy based on PID control is studied,and a heave displacement compensation strategy based on position compensation adaptive robust sliding mode backstepping control algorithm is proposed.Theoretical analysis and simulation verification of the proposed method show that the proposed adaptive robust sliding mode backstepping control algorithm is superior to the conventional PID heave displacement compensation algorithm in terms of control accuracy and robustness.Fourthly,in view of the large inertia,high load and strong interference of the system,which lead to the response lag of the wave compensation system,a wave prediction method based on the ESN echo state network is proposed,which is compared with the method based on the AR model and the ELMAN neural network in terms of prediction accuracy and response time.Fifthly,for the problem that affects the accuracy of floating cranes,a model prediction compensation control method based on ocean wave prediction is proposed to improve the control accuracy and performance of the floating crane system.The method is simulated and studied to verify the effectiveness of the proposed method.This method effectively solves the problems of fast response and robustness of the wave compensation system,and provides strong support for the application of the wave compensation algorithm.Finally,this thesis has designed and made a set of offshore floating crane compensation structure,including the design of the hardware system and PC program written using labview software control the movement of the wave simulation platform.The algorithm proposed in this thesis is verified to realize the heave displacement of the compensation mechanism.Compensation experiment and multi-degree-of-freedom lifting object leveling experiment have obtained good experimental results.