Fu Mingyu

Research on heading control of Air Cushion Vehicle

Air cushion vehicle (ACV) is a type of high performance watercraft. ACV can be propelled forward over the water, the ground and swale. It is widely used in both the civilian and military. Its operation is very different from general ships because of the structural particularity. We designed PID controller and neural net (NN) controller used for ACV heading control. Simulation results show that NN controller performs better than normal PID controller in heading control of ACV, especially when ACV is disturbed by wind.

Output feedback control for dynamic positioning vessels using nonlinear observer backstepping

A horizontal 3 degree-of-freedom(DOF) ship model and environment model are established. Passive nonlinear observer which is extended to include more nonlinear terms of damping and Coriolis matrix is proposed, observer is used to filter the wave induced high frequency motion and give the state variable estimations. Then backstepping control method based on observer estimated values is obtained. The Global Uniformly Stability properties of observer-controller system are analyzed by applying Lyapunov stability theory. Simulation about a surface DP vessel is carried on to verify the performance of the entire guidance-control system.

Fault diagnosing system of steam generator for nuclear power plant based on fuzzy neural networks

All kinds of reasons are analysed in theory and a fault repository combined with local expert experiences is established according to the structure and the operation characteristic of steam generator in this paper. At the same time, Kohonen algorithm is used for fault diagnoses system based on fuzzy neural networks. Fuzzy arithmetic is inducted into neural networks to solve uncertain diagnosis induced by uncertain knowledge. According to its self-association in the course of default diagnosis, the system is provided with non-supervise, self-organizing, self-learning, and has strong cluster ability and fast cluster velocity.

Finite-Time Tracking Control for a Class of MIMO Nonlinear Systems with Unknown Asymmetric Saturations

This paper addresses the problem of finite-time tracking control for multiple-input and multiple-output (MIMO) nonlinear systems with asymmetric saturations. A systematic approach is proposed to eliminate the effects of unmeasured external disturbances and unknown asymmetric saturations. In the proposed control strategy, a terminal sliding mode disturbance observer is provided to estimate the augmented disturbance (which contains the unknown asymmetric input saturation and external disturbance). The approximation error of the augmented disturbance can converge to zero in a fixed finite-time interval. Furthermore, a novel finite-time tracking control algorithm is developed to guarantee fast convergence of the tracking error. Compared with the existing results on finite-time tracking control, the chattering problem and the input saturation problem can be solved in a unified framework. Several simulations are given to demonstrate the effectiveness of the proposed approach.

Trajectory tracking control during offshore pipe-lay operation based on back-stepping sliding mode method

Pipe-lay operation is an important special operation coordinated with dynamic positioning system in ocean engineering, with trajectory tracking of pipe-laying being a kind of special uncertain nonlinear system output tracking issue. The relation of the desired trajectories of pipe and vessel was discussed firstly. The kinematic and dynamic model for the vessel and pipe forces was developed then. The back-stepping sliding mode method was adopted to design the controller in two steps with the sufficient condition of the stability given based on the Lyapunov function. The validity of the designed controller was certified by a case for simulation. An available method for describing and realizing the similar output tracking control was offered.

Robust adaptive backstepping path tracking control for cable laying vessel based on guidance strategy

In order to ensure the cables are laid on set paths during offshore cable laying and burying operations, a novel control method with adaptive robustness for dynamic positioning cable laying vessels is proposed. A guidance strategy used to calculating the vessel desired position vector from set cable laying paths is proposed. The uncertain parameters matrix of the vessel without extra sensors on cable laying equipment is estimated, and disturbances from environment and cable plough are compensated for by the nonlinear adaptive method. The global asymptotic stability of the closed-loop system is proved. Simulation results show that, with the proposed control method, the closed-loop system has stability and robustness to large disturbances, the position and speed response of the vessel is fast, and cables are laid on the set paths accurately.

Simulation and spectral estimation of sea wave based on shaping filter

This paper deals with the method of simulating sea wave for decreasing its disturbance in the watercraft navigating. Firstly the ITTC two-parameter spectrum is selected as the power spectrum of sea wave to be simulated. Secondly the selected power spectrum is approximated by the rational spectrum and its coefficients are calculated by least squares method. Finally the shaping filter is concluded and the simulated sea wave is obtained by inputting white noise to the shaping filter. The spectrum analysis by Welch verifies the simulated sea wave. Without loss of generality, this method is practical in engineering and important for the operating parameters of watercraft prediction and filtering, the forcast of sea wave and marine dynamic positioning.

Research on positioning operation control method of J-lay vessel

Ship mathematical model and environmental disturbance model of a J-lay vessel are built, the model of pipe horizontal forces and moment acting on the ship is built by catenary theory. In order to avoid the ships high frequency motion component disturbing the closed-loop control system, passive nonlinear observer is applied to estimate the vessels low frequency variables during positioning process. Ship positioning operation controller is designed by the acceleration feedback and PID control strategy with pipeline action as feedforward term. Simulation results are used exclusively to demonstrate the observer and controller with established model for J-lay vessel.