Yuanhui Wang

Structural Reliability Based Dynamic Positioning of Turret-Moored FPSOs in Extreme Seas

FPSO is widely used during the deep-sea oil and gas exploration operations, for which it is an effective way to keep their position by means of positioning mooring (PM) technology to ensure the long-term reliability of operations, even in extreme seas. Here, a kind of dynamic positioning (DP) controller in terms of structural reliability is presented for the single-point turret-moored FPSOs. Firstly, the mathematical model of the moored FPSO in terms of kinematics and dynamics is established. Secondly, the catenary method is applied to analyze the mooring line dynamics, and mathematical model of one single mooring line is set up based on the catenary equation. Thereafter, mathematical model for the whole turret mooring system is established. Thirdly, a structural reliability index is defined to evaluate the breaking strength of each mooring line. At the same time, control constraints are also considered to design a state feedback controller using the backstepping technique. Finally, a series of simulation tests are carried out for a certain turret-moored FPSO with eight mooring lines. It is shown in the simulation results that the moored FPSO can keep its position well in extreme seas. Besides, the FPSO mooring line tension is reduced effectively to ensure mooring lines safety to a large extent in harsh sea environment.

Dynamic positioning particle filtering method based on the EnKF

In order to improve the positioning accuracy and reliability of ship dynamic positioning system and sovle the problem of Gaussian and nonlinear system state estimation effectively, a method of combing ensemble Kalman filter(EnKF) and particle filter was proposed by using the max of posterior probability density to generate the importance density function of particle to help the importance probability density function integrate into the latest observation information and at the same time more accord with the posterior probability density distribution of the true state. The effectiveness of the algorithm is verified by the simulation results.

Way-point tracking control for air cushion vehicle

A way-point tracking control strategy which contains switching speed and radius that consider the safe bound of heeling angle and rotation rate during the rotation is designed in view of the requirements of air cushion vehicle (ACV) track control. Firstly, the four-degree-of-freedom mathematical motion model of ACV is established. Secondly, active disturbance rejection control (ADRC) controller whose parameters are tuned by genetic algorithm (GA) is designed to guidance ACV sailing along the tracking route. Thirdly, the switching strategy which calculates the expected switching radius and rotation speed of ACV by functions is designed. Finally, a series of simulation experiments are carried out with winds as feed forward interference in view of ACV being affected by the environment easily. The simulation results verify the effectiveness of the algorithm. It also shows that the GA-ADRC controller has better control effect than traditional ADRC controller.

Dynamic data outliers eliminating and filtering Method for motion information of hovercraft

Normally, hovercraft movement need to be controlled by its motion parameters. The parameters after filtering can improve the control quality of hovercraft. To overcome the problem that the data measuring with hovercraft high-speed maneuvering always have missing value, outliers and noise, and so on. A method is selected to solve such problems. Firstly, supplement the missing value through the interpolation method. Then use polynomial fitting method based on wright guidelines and least squares method to exclude outliers. Finally, use wavelet decomposition and reconstruction method to achieve data filtering smoothing. A series of simulation experiments were carried out to validate that the proposed data filtering methods are useful and effective.

Passivity analysis and design of a haptic interface

The haptic interface provides the virtual environment for the remote servo manipulator, and it can make the operator feel and manipulate the remote or virtual environment. For arbitrary passive operator (human), the stability not only relates to the parameters of the haptic device and the virtual environment, but also relates to the type of the sampling signal of the system. The passivity conditions for haptic interface systems with position sampling are given in existing works, but the parameters scope for passivity design is very small. In view of this, velocity of the haptic device is used for the sampling signal in this paper, and a wider passive region is derived based on the frequency response of a sampled-data control system. At last, through overall consideration of the bandwidth, damping ratio and passivity requirements, a reasonable design result is given in the paper.

Adaptive synchronization control of multiple vessels with time delays

In this paper, an adaptive synchronization control approach is presented to control multiple fully actuated vessels along desired trajectory. And the communication network among these vessels is directed strongly connected but not necessarily balanced. Meanwhile, the control strategy is to synchronize each vessel with others in position and velocity. In addition, the proposed decentralized synchronization control law is adaptive in the presence of model parameter uncertainty and the constant coupling time delays. A combination of the Lyapunov theory and the mathematical graph theory has been used to validate the stability of the whole system. Finally, simulations of the proposed adaptive synchronization control algorithm are presented and discussed.