Guoqing Xia

The application of self-tuning fuzzy PID control method to recovering AUV

The dynamic positioning to line strategy and self-tuning fuzzy PID method are used to research on the control of recovering Autonomous Underwater Vehicle (AUV) by underwater ocean workstation in this paper. According to the AUV special shape and motion characters, the mathematic model of AUV is established. According to the high precision of position requirement, the two-point (the bow and the stern) dynamic positioning method (dynamic positioning to line method) is proposed, and self-tuning fuzzy PID theory is used to design the AUV four degrees of freedom controllers. The simulation results demonstrated that self-tuning fuzzy PID controller is more suitable than PID controller to solve the problems.

Design of dynamic positioning systems using hybrid CMAC-based PID controller for a ship

The ship motion is a type of complicated nonlinear motion. It is very difficult to measure the precise hydrodynamic parameters when the ship is at sea. Moreover, the external disturbance forces coming from wind, waves and water current are changing at any moment. So, it is necessary to study new control techniques, with robust and adaptive properties, to implement precise position for dynamic positioning vessels. PID control law is a good robust and adaptive control law for a type of definite systems that precise modeling can be gotten in mathematics. But PID control results are not satisfactory for complex nonlinear systems such as ship motion. The neural network has self-learning and adapting ability, so we can combine the PID with neural network to build the strong robust and adaptive controller. In this paper, CMAC-based PID controller is studied. The simulation results show that the new control method is effective with strong robust and adaptive capability, and it can be applied to marine dynamic positioning systems.

Fuzzy neural network-based robust adaptive control for dynamic positioning of underwater vehicles with input dead-zone

This paper proposes a design for a robust adaptive controller for the Dynamical Positioning (DP) of underwater vehicles with unknown hydrodynamic coefficients, unknown disturbances and input dead-zones. First, for convenience of controller design, the Multi-Input Multi-Output (MIMO) system is divided into several Single-Input Single-Output (SISO) systems. Next, a Dynamic Recurrent Fuzzy Neural Network (DRFNN) with feedback loops is employed to approximate the unknown portion of the controller, which can greatly reduce the number of neural network inputs. A fuzzy logic dead-zone compensator is designed to cope with the unknown dead-zone characteristics of actuators. The upper bounds of the approximation errors and disturbances of the network, which are often used in existing works, are not necessary in this paper due to the presentation of a special robust compensator. Stability analysis is conducted according to the Lyapunov theorem, and the tracking error is proved to converge to zero. Simulation results indicate that the proposed controller demonstrates good performance.

EKF based model identification for a relaxed dynamic positioning ship using NMPC method

The extended Kalman filtering (EKF) based identification is an effective identification technology. It has made successful applications in ship model identification fields to cruise-speed ships. This paper introduces it to the dynamic positioning (DP) ship model identifications. The DP ship is of different motion characteristics with that at the cruise-speed. Because the ship speed is close to zero, DP ships are easily affected by the sea environment disturbances, which makes the identification difficult. In order to assure the correctness and improve the accuracy of the DP ship model identification, the batched identifications regarding to different degree of freedom (DOF) is necessary and must. The main hydrodynamic parameters which affect the ship motion characteristics primarily are need to successfully identify firstly, and then, other hydrodynamic parameters are identified in 3 DOF coupling ship motions. After the identification, the identified ship model is tested, to verify whether the motion characteristics of the identified model is basically consistent with the actual ship. Also a model based control method - nonlinear model predictive control (NMPC) is designed to test the controlling performance which reflects the correctness and accuracy of the identified ship model meeting requirement from aside.

Research on the fuzzy decoupling in the coordinated control system of nuclear power plant

A fuzzy decoupling strategy with a compensator and a design method for the decoupling compensator are put forward based on the research on the decoupling control theory for a multivariable coupling nuclear power system. The designing method for the compensator is discussed. The fuzzy decoupling and compensating table is designed in detail for the double inputs and double outputs control system. The fuzzy decoupling technology is applied to design of the decoupling compensator for the basic class of coordinated control system of a nuclear power system, and a control system structure is present in the paper also. Under the typical load disturbance, the simulation result shows that the coordinated control system with the fuzzy decoupling strategies is better than the coordinated control system without decoupling strategies, especially good for the steam pressure of steam generator.

Realization of Integration Technology of Ship Collision Avoidance System based on HLA

Integration technology is an exciting emerging area with good prospect. As a common distributed interactive simulation standard, High Level Architecture (HLA) mainly emphasizes on the reusability and interoperability of different simulation components. So it can be successfully applied in integration area. Any existing simulation program with special function can be integrated into distributed simulation system based on HLA, and then become reusable unit in HLA federation development. This paper takes a ship collision avoidance simulation system as an example to present the integration method by HLA. Simulation scenario, federation object model (FOM) and simulation object model (SOM) are established according to available system function modular structure. Finally, a ship collision avoidance simulation system based on HLA is established on the software development platform of VC2003.net.The collision avoidance simulation results validate the integration method based on HLA. Moreover, the developed system is good at flexibility and expandability and easy to evolve and upgrade to more complex multi-functional collision avoidance simulation integration system.

Low-cost MEMS-INS/GNSS integration using quaternion-based nonlinear filtering methods for USV

This paper addresses the problem of integration of Inertial Navigation System (INS) and Global Navigation Satellite System (GNSS) in the field of developing low-cost, robust and highly accurate navigation systems. With the implementation of the navigation system of an unmanned surface vehicle (USV) as background, a tightly-coupled integration filter based on quaternion has been proposed. The proposed filter avoids the singularity problems inherited in Euler angle-based approaches, and the quaternion vector involves less elements than DCM-based approaches. Due to the nonlinearity of process and observation models of the system, as well as the non-Gaussian distribution of stochastic measurement errors of MEMS (micro-electromechanical systems) sensors, a modified unscented particle filter (UPF) that combines the particle filter (PF) and unscented Kalman filter (UKF) has been presented. For nonlinear and non-Gaussian estimation problem, PF is extremely theoretically attractive to be used. However, PF is seldom to be seen in practical engineering application for its large computation burden. Considering the purpose of releasing the computation burden, meanwhile, guarantying the estimation accuracy, quaternion based UPF is a good choice to implement INS/GNSS integration for USV navigation system.

Nonlinear model identification of a ship using recursive subspace methods

In this paper, we propose an online identification algorithm of ships for the dynamic positioning system. The ship model is first changed into Hammerstein form, then subspace identification method is used, with its simplicity and robustness, to perform the identification procedure. In order to make the identification algorithm more practical for online application, an effective updating strategy is proposed with Givens rotation matrices introduced. The proposed online identification method is tested on a DP-3 simulation system, with the assumption that the ship is operating under a calm sea condition, but the noise interference of the input/output measurement is considered. At last, simulation results showed the feasibility and effectiveness of the proposed identification method.

Dynamic Positioning Control System with Input Time-Delay Using Fuzzy Approximation Approach

In this paper, a backstepping controller using fuzzy approximation approaches is proposed to solve the problem of input time-delay and disturbances pertaining to ship dynamic positioning. Using fuzzy approximating to disturbances and unmodeled dynamics, backstepping control law is designed to stabilize ship positioning with input time-delay via Lyapunov approach. In order to demonstrate the effectiveness and superiority of the proposed method, simulation studies and comprehensive comparisons with PID control are conducted in the presence of complex disturbances. Simulation results show that the proposed method is superior to conventional PID control in terms of accuracy and response.

Multi-AUV cooperative task allocation based on improved contract network

This paper studies multi-AUV cooperation as the research object, aiming at the problems that the traditional contract network has low overall efficiency, unreasonable distribution and coexistence of multiple tenders, a multi-AUV target allocation strategy based on improved contract network is proposed. This paper introduces the token ring network can improve the efficiency of AUV internal communication and solve the coexistence of multiple tenders, the introduction of task load rate indicators to solve the problem of unreasonable allocation of tasks. The combination of the two can effectively improve the overall efficiency. The simulation experiment in the three-dimensional environment shows that the improved contract network can improve the overall efficiency and make reasonable allocation scheme.