Xinqian Bian

Simulation of optimal integral sliding mode controller for the depth control of AUV

The depth control problem is described and addressed for a small autonomous underwater vehicle in this paper. Based on the nonlinear model of AUV in vertical plane, the paper established a mathematical model of AUVs depth motion in vertical plane by linearizing the model at a specified operating point. An optimal integral-sliding-mode controller was designed for the AUV depth control system by constructing a sliding mode surface with quadratic optimization. And a saturation function was introduced to reduce system chatting. The results of simulation demonstrated that this proposed controller was effective to eliminate the disturbances caused by AUVs nonlinear and model uncertainty. Meanwhile the system showed a better performance both in speedness and robustness compared than a PID controller.

Nonlinear feedback control for trajectory tracking of an unmanned underwater vehicle

This paper presents a nonlinear input-state feedback linearization controller for tracking trajectory on horizontal plane with the rudder of an unmanned underwater vehicle (UUV). UUV system is strongly nonlinear, but the model is often simplified into linearization under some strict assumptions in some traditional linear control methods for the need of the control laws, and the linearization may induce large modeling errors and cause severe problems in the practical applications. In this paper, an input-state feedback linearization controller is designed to transform the nonlinear UUV model into an equivalent linear model. The trajectory tracking system is confirmed to be stable and UUV tracks trajectory approximately by pole placement through properly choosing the virtual input. Simulation results illustrate the system is stable and has robust with proposed control scheme.

Adaptive neural network control system of bottom following for an underactuated AUV

The bottom following control problem of an underactuated autonomous underwater vehicle (AUV) was addressed in this paper. In order to deal with the parameter variations and uncertainties due to time-varying hydrodynamic damps, the RBF neural network (NN) was introduced to estimate unknown terms where an adaptive law was chosen to guarantee optimal estimation of the weight of NN. Based on the Lyapunov stability theorem, an adaptive NN controller was designed to guarantee all the error states in the diving control system were asymptotically stable. Two bottom profiles, one with constant slopes and the other with real measured data were used to evaluate the performance of the bottom following controller. Simulation results demonstrated that the proposed controller was effective to eliminate the disturbances caused by vehicles nonlinear and model uncertainty.

Notice of Retraction Research on Wave Disturbance Acting on Large Ship with 4 Degree of Freedom Motion

It is well known that the wave motion is a really complex process and hard to be simulated. The paper mainly solves the difficult problem of numerical simulation of wave disturbances in ship motion simulation area. The wave disturbance force and moment acting on the ship sailing on the sea are simulated. Based on statistics superposition theory, Pierson-Moskowitz (P-M) single-parameter standard wave spectrum is used to simulate a random long-crested sea wave. A kind of wave disturbance mathematical model is established, according to which the random wave disturbance force and moment acting on a large ship is calculated and simulated real time in the typical conditions of sea state 4. The influence of ocean wave to the large ship is also analyzed through the simulation research of the movement track and course change of the large ship under certain ocean waves. As the simulation results shown, the obtained wave disturbance force and moment is basically accorded with the real situation. At the same time, it shows that the ocean wave has great influence on 4 degree of freedom (DOF) large ship, which cant be ignored in engineering research. To some extent, the established wave disturbance mathematical model may contribute to the further research on the area of ship motion and offshore operation.

Adaptive controller—Based on Nonlinear Disturbance Observer using for UUV automatic recovery system

UUV(Unmanned Underwater Vehicle) recovery system is a very complex multivariable system with strong coupling, strong nonlinear, time-varying and unknown interference. This dissertation is aimed to design an adaptive controller based on Nonlinear Disturbance Observer (DOB) under the unknown environment of near-wall during the coming-down of UUV recovery process. As a result, DOB can not only compensate the unknown inferences, but also eliminate the high frequency noise from sonar by the low pass filter in DOB. This paper solves the problem of UUV automatic recovery system by flat-carrying underwater.

A study on the influence of cable tension on the movement of cable laying ship

A cable laying ship is a deep-sea vessel designed and used to lay underwater cables for telecommunications, electricity, and such. Cable ships are distinguished by large cable sheaves for guiding cable over bow or stern or both. The movement of the cable and the influence of the cable tension on the movement of the cable laying ship are two key problems to be solved during the cable laying operation simulation. But in the process of cable mathematic model being established, too many factors bring great difficulties to the research of the cable modeling. It is necessary to reach a higher precision for the established model to ensure the cable tension in great practical value. Besides, a simplified model with less computing work and lower complexity is also needed to meet the requirement of computer real-time simulation. At first, it brings forward one easy and useful method to solve the problem of cable modeling. Linear and nonlinear methods are adopted separately to build up the underwater cable dynamic model. The analytical formula of the cables shape is presented. The cable tension acting on the ship are also computed out under a given ship motion state. Then, a ships model is established with a three degree-of-freedom including surge, heave and pitch, according to the cable laying operation based on some assumptions. And the cable ship mathematical models are established considering the cable tension on the relevant three degree-of-freedom. Further more, the cable model and the cable tensions influences on the ship movement are simulated in some computer test. Finally, through these simulation tests, the relations between the cable tension on the ship and ship speed, the cable tension and the cable laying velocity, the cable tension and the water depth are analyzed. Moreover, the concrete influences of the cable upon the ship at three degree-of-freedom motions are concluded. The modeling, simulation results and conclusions are in great value for engineering use, which provide effective theory basis for a cable ships motion simulation and control research.

Current profile data aided positioning for autonomous underwater vehicles

The positioning problem of current profile data aided dead reckoning (DR) for autonomous underwater vehicle is addressed in this paper. Various types of instrumentations have been developed for ocean exploring, including conductivity temperature and depth (CTD), multi-beam sonar (MBS) and side scan sonar (SSS). During the measurement, the displacement which is going to be generated by DR, global position system (GPS), inertial navigation system (INS), or long baseline (LBL) must be considered seriously, because an ocean diagram measured by these sensors need this information badly. The doppler velocity log (DVL), which plays an important role in generating a reliable displacement, may be out of work sometime. In order to deal with the dropout or failure of DVL, the current track velocity measured by acoustic doppler current profilers (ADCP) is proposed to substitute for the bottom track velocity, which is going to be used by DR algorithm. The post-processing experiment demonstrates that the proposed DR position solution is not only low-cost, but also accurate.

Simulation research of H ∞ filter for the pitch control of AUV

A H ∞ filter is proposed to suppress the adverse effects generated by the measurement noise in the pitch control system of an autonomous underwater vehicle. A kinetic model of AUVs pitch motion in vertical plane is established by linearizing the nonlinear model at a specified operating point. Based on LMI Lab, it is possible to design a global optimal H∞ filter for an accurate estimation of the contaminated states which are very important inputs to the feedback controller. It is reported that this filter is effective to eliminate the negative effects caused by measurement noise. And the accurate estimation to the system states means a lot for systems lacking disparate measurement.

Optimal design for consensus of second order multi-agent systems with damping term

This paper presents a LQR-based optimal design method for consensus of second order multi-agent systems with damping term in an undireceted communication topology. Concerning about the undirected connected topology, a Lyapunov based method is carried out to guarantee the asymptotical consensus of systems. Being different from previous researches, this paper takes the damping term into consideration and forms the velocity dynamics. Besides, it is derived that the consensus value is related with its parameter. In addition, simulations are carried out with simplified heading control systems of autonomous underwater vehicles (AUVs), which show the effectiveness of the proposed optimal design method.

Robust diving control of AUV with L 2 disturbance attenuation method

Towards the diving control of an autonomous underwater vehicle (AUV), a robust controller built upon L2 disturbance attenuation method with recursive backstepping technique is addressed. External disturbances are eliminated through L2 controller. A robust controller incorporated with switching control scheme is proposed against the parameter uncertainties with guaranteed stability. Different from conventional parameter adaptive learning method, the decreasing problem of learning precision can be avoided due to the fast varying of uncertain parameters, and parameter switching law can be obtained through the Lyapunov stability theory. The proposed controller yields asymptotical convergence to the given depth for the vehicle. Finally, simulation experiments are employed to illustrate the effectiveness of the proposed control scheme.