Adaptive nonlinear ship tracking control with unknown control direction

This paper is to suggest a novel design for ship tracking control of the benchmark Norrbin nonlinear ship model under relaxed conditions. The challenges of the problem under investigation include the uncertain or absent information of the model time constant, the uncertain reference course, and the intrinsic environmental disturbances. We formulate the ship tracking control problem in terms of a nonlinear output regulation problem with unknown control direction and uncertain exosystems. To solve the problem, we first adopt a novel internal model candidate to convert the output regulation problem into a stabilization problem for an augmented system. Then, a Nussbaum‐gain‐based stabilizer is developed for the augmented system to complete the design. Simulation results are presented to show the effectiveness of the proposed controller.     

Robust dynamic ship positioning control system design and applications

This paper describes the robust control system design for a ship dynamic positioning system. The control design is based on an approximate linear model derived from the nonlinear hydrodynamic equations governing the horizontal motions of the ship. The nonlinear models of the ship, seawaves, current, wind and thrusters are derived and simulated for control design verification. The H_∞ control design technique is employed to design the controller. The control problem is formulated in state‐space form and the design specifications are translated into requirements on the weighting functions of the error signal and the thrusters input. A tuning procedure is proposed based on the wind and wave disturbances. The controller is initially tested on the nonlinear ship model and simulation results are presented to demonstrate the robustness of the H_∞ controller. Tank tests results are then presented to assess the controller performance. Copyright © 2001 John Wiley & Sons, Ltd.     

Robust nonlinear ship course‐keeping control by H∞ I/O linearization and μ‐synthesis

In this paper, the H_∞ input/output (I/O) linearization formulation is applied to design an inner‐loop nonlinear controller for a nonlinear ship course‐keeping control problem. Due to the ship motion dynamics are non‐minimum phase, it is impossible to use the ordinary feedback I/O linearization to resolve. Hence, the technique of H_∞ I/O linearization is proposed to obtain a nonlinear H_∞ controller such that the compensated nonlinear system approximates the linear reference model in I/O behaviour. Then a μ‐synthesis method is employed to design an outer‐loop robust controller to address tracking, regulation, and robustness issues. The time responses of the tracking signals for the closed‐loop system reveal that the overall robust nonlinear controller is able to provide robust stability and robust performance for the plant uncertainties and state measurement errors. Copyright © 2002 John Wiley & Sons, Ltd.     

Minimum time ship maneuvering method using neural network and nonlinear model predictive compensator

In this paper, a new minimum time ship maneuvering method using neural network (NN) and nonlinear model predictive compensator is proposed. In this proposed method the NN is used for interpolating the precomputed minimum time solution for real time situations and the nonlinear dynamical model of a ship is used for compensating the control error caused by some modeling errors, disturbances and so on. The introduction of the nonlinear model into the online control system is inspired by the idea that since the nonlinear dynamical model of a ship has been constructed for the off-line numerical computation of the optimal solutions, it could also be used to enhance online control performance. In order to investigate this method, simulation studies and actual sea tests were carried out using a training ship Shioji Maru.The results showed that the system gives approximate solutions in a short computing time and good tracking performance in the actual sea trials.     

控制增益未知的船舶航向非线性自适应跟踪控制

针对参数不确定的船舶运动非线性控制系统控制方向未知的困难,将逆推算法与Nussbaum增益方法相结合,提出一种新的自适应非线性控制策略,从而实现船舶运动航向跟踪控制.首先,从理论上证明了所设计的自适应控制器保证最终的控制系数符号未知的参数不确定船舶运动非线性系统中所有信号一致有界,船舶的实际航向全局自适应地渐近跟踪期望的参考航向.对两条船舶数学模型的仿真实验结果表明,所设计的自适应非线性跟踪控制器具有良好的适应性及鲁棒性.     

An application of dynamic positioning control using wave feed forward

The paper presents the results of model tests for a large tanker in which wave drift force feed forward was applied in the dynamic positioning control system. The estimation method of the nonlinear (second order) wave drift forces from the measurement of relative water motions at the side of a ship hull is presented. The estimated wave drift forces are used in the DP control system, to enhance the filter process of the extended Kalman filter, and in the required thruster set‐points. The EKF uses the nonlinear equations of low‐frequency ship motions on the horizontal plane, which are also presented. The results of the model tests show that the use of wave drift force feed forward significantly improves the positioning accuracy in sea states with 3.5 m significant wave height or higher. Copyright © 2001 John Wiley & Sons, Ltd.     

柴油发电机组非线性H2/H∞调速器的研究

船舶电力系统频率的稳定性主要取决于船舶电站柴油机调速系统的转速响应特性. 船舶电站柴油机调速系统是一个非线性控制系统, 为了分析系统的动态特性, 首先建立柴油机调速系统的非线性数学模型, 然后以此为基础设计非线性H2/H∞速器. 将直接反馈线性化和混合H2/H∞控制理论相结合应用于柴油发电机组调速器的设计,把系统的性能要求转化为标准H2/H∞控制问题, 获得了柴油机非线性H2/H∞转速控制律. 计算机仿真结果表明, 设计的非线性H2/H∞调速器有效地提高了系统的动态精度和抑制扰动的能力, 改善了船舶电力系统频率的稳定性.     

动力定位船舶纵向运动的反步法控制器设计

本文研究了动力定位系统的控制策略,针对船舶动力定位系统模型的非线性特性,考虑到风浪流等外部环境扰动对船舶引起的恒值干扰及其不确定性,基于带有未知定常扰动的三自由度非线性船舶水面运动数学模型,应用自适应反步法设计船舶动力定位控制律,将Lyapunov函数选取和控制器设计相结合的回归设计方法,并在MATLAB软件环境下通过仿真研究验证模型和控制策略的有效性。在计算机仿真研究中,以26:1比例建造的2800mm×762mm×498mm船模为设计实例。     

Iterative method based on CFD data for the assessment of seakeeping control effects,considering amplitude and rate saturation

An iterative procedure for the frequency domain evaluation of control effects in nonlinear loops is introduced. The article focuses on ship seakeeping control, to attenuate ship motions. There is no model of the ship, only CFD tabulated data. The proposed procedure could be used for design or empirical tuning of a controller. The actuators have angle and rate limits. In the case of a ship, the actuators are submerged moving wings: flaps, fins and T‐foil. The control evaluation procedure uses a describing function approach. The paper considers amplitude and rate saturation in series. The results are validated with experiments using a scaled ship in a towing tank facility. Copyright © 2010 John Wiley & Sons, Ltd.     

船舶减摇非线性系统神经网络控制研究

本文针对船舶横摇运动的非线性模型，基于BP神经网络设计了一种船舶横摇减摇 自适应PID控制器．该控制结构由两个BP神经网络组成,实现了对被控对象输出的预测及PID控制器参数的自整定．仿真表明该控制器对减摇系统的非线性模型有很好的减摇效果．     

Model reference adaptive control of a nonlinear oscillator

A model reference adaptive system (MRAS) is applied to a nonlinear oscillator to achieve adaptive control. Since the model and plant of the system are not linearized to achieve the adaptive laws, the true behavior of the strongly nonlinear system is not lost. By considering important properties of the reference model describing a well-behaved nonlinear oscillator, it is possible to derive the error-equation, which is linear in the state variables. Liapunov synthesis is used to achieve adaptive control, and stability is thus guaranteed. The technique is simulated using an adaptive autopilot for a ship.     

基于FAL函数滤波的动力定位自抗扰控制器设计

针对动力定位系统数学模型不够精确,而且具有很强的非线性特性问题,采用自抗扰控制算法设计其控制器.该控制算法无需精确的数学模型,主要利用扩张状态观测器估计船舶运动位置、速度和总扰动,最后通过反馈控制对其进行补偿,从而实现船舶动力定位的精确控制.但实际工程中,船舶的测量系统的测量噪声是难以避免的,为了避免测量噪声的影响,针对所设计的扩张状态观测器采用FA L函数滤波器,在测量信号进入扩张状态观测器之前进行滤波,以减小测量噪声的影响.从而使得其反馈控制更加精确.最后以一艘供给船为例进行仿真分析,验证了所设计非线性控制器的有效性和鲁棒性.     

A variable‐structure gradient RBF network with its application to predictive ship motion control

The prediction of dynamic behavior of the nonlinear time‐varying process plays an important role in predictive control applications. Although neural network algorithms have been intensively researched in modeling and controlling nonlinear systems in recent years, most of them mainly focused on the static dynamics. In this paper, a variable‐structure gradient radial basis function (RBF) network is implemented for nonlinear real‐time model predictive control, which is achieved by the proposed gradient orthogonal model selection (GOMS) algorithm. By learning the gradient message of real‐time updated data in a sling window, the structure and the connecting parameters of the network can be adaptively adjusted to adapt to the time‐varying dynamics. The proposed algorithm is evaluated with Mackey‐Glass chaotic time series prediction. Moreover, the variable structure network achieved by GOMS algorithm is applied as a multi‐step predictor in a ship course‐tracking control study, results demonstrate the applicability and effectiveness of the proposed GOMS algorithm and the variable‐RBF‐network based predictive control strategy. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

零航速减摇鳍自适应主从控制器设计

零航速下鳍上的水动力与鳍角,角速度和角加速度存在记忆非线性关系,同时船舶横摇模型本身亦具有非线性和不确定性.导致常规控制方式无法直接求取控制量,且不能适应变化的模型和海况.本文通过主从控制器来分离减摇鳍系统的输出和输入非线性,对分离后的系统,采用基于径向基网络的逆控制构成主控制器来求取中间控制量,并自适应横摇模型和海况的变化.采用广义回归神经网络来逼近中间控制量到鳍角的映射作为从控制器.仿真结果表明该方法对横摇模型的不确定性具有自适应性,并可提高在变海况和高海况下的减摇效果.     

柴油机自适应遗传非线性PID调速控制仿真

研究船用柴油机控制优化问题,柴油机调速要求快、稳、准。针对船用柴油机调速系统的时变、非线性及外界干扰等特点,传统PID调速稳定时间长,控制效果不佳。为提高喷油量达到控制准确度,改善调速系统性能,提出了一种柴油机自适应遗传非线性PID调速控制策略。采用Matlab对柴油机调速系统模型进行辨识并验证其准确性。利用非线性PID控制实现各参数增益的实时调整,提高了抗干扰能力,通过自适应遗传算法对系统的动态偏差进行监控,优化非线性PID控制器参数,减少了超调量,提高控制精度。仿真结果表明,采用自适应遗传非线性PID控制器稳定时间更短,鲁棒性强,控制精度更高,优化了柴油机调速系统性能。     

全航速升力反馈减摇鳍控制策略研究

提出全航速减摇鳍控制策略,对低航速和中航速切换策略进行研究．采用升力反馈封装鳍角到升力的不确定性,避免在零航速和低航速下复杂的控制规律;同时,基于T-S模型将横摇非线性不确定系统转化为线性时变系统,并将控制中的约束非线性优化问题转化为二次规划问题,避免了预测控制中的非线性优化在线求解．以某船为例,给出了低中航速的切换控制策略,仿真结果表明了该方法可以使减摇鳍满足全航速减摇要求．     

Modelling and parameter estimation of a ship boiler

This paper deals with the identification and parameter estimation part of an adaptive control system for a ship boiler. The adaptive control system should be of such a form that it could be implemented on a minicomputer and easily adjusted to other ship boilers with similar characteristics. A nonlinear model of the process, suitable for parameter estimation purposes will be presented and the Extended Kalman filter approach to the estimation problem will be studied. Results based on plant measurements and simulations will be given.     

喷水推进型无人艇航向跟踪的反步自适应滑模控制*

针对单泵喷水推进型无人滑行艇的航向跟踪非线性系统,提出了一种反步自适应滑模控制方法。该系统由无人艇运动非线性响应模型和舵机伺服系统组成,并考虑运动响应模型的建模误差、外界干扰力等非匹配不确定性,利用全局微分同胚坐标变换将原系统变换为具有下三角特征的非线性系统。基于Backstepping方法和滑模控制理论,提出了一种自适应滑模控制律;利用Lyapunov函数,证明该控制律保证了航向跟踪系统的全局渐近稳定性。仿真对比结果验证了所提出控制器的有效性。     

Nonlinear backstepping ship course controller

A ship, as an object of course control, is characterized by a nonlinear function describing the static maneuvering characteristics. The backstepping method is one of the methods that can be used during the designing process of a nonlinear course controller for ships. The method has been used for the purpose of designing two configurations of nonlinear controllers, which were then used to control the ship course. One of the configurations took dynamic characteristic of a steering gear into account during the designing stage. The parameters of the obtained nonlinear control structures have been tuned to optimise the operation of the control system. The optimisation process has been performed by means of genetic algorithms. The quality of operation of the designed control algorithms has been checked in simulation tests performed on the mathematical model of a tanker. The results of simulation experiments have been compared with the performance of the system containing a conventional proportional-derivative （PD） controller.     

基于非线性增益递归滑模的船舶轨迹跟踪动态面自适应控制

针对三自由度全驱动船舶存在模型不确定和未知外部环境扰动的情况,设计出一种基于非线性增益递归滑模的船舶轨迹跟踪动态面自适应神经网络控制方法.该方法综合考虑船舶位置和速度误差之间关系设计递归滑模面,引入神经网络对船舶模型不确定部分进行逼近,设计带σ-修正泄露项的自适应律对神经网络逼近误差与外界环境扰动总和的界进行估计,并应用一种非线性增益函数构造动态面控制律,选取李雅普诺夫函数证明了该控制律能够保证轨迹跟踪闭环系统内所有信号的一致最终有界性.最后,基于一艘供给船进行仿真验证,结果表明,船舶轨迹跟踪响应速度快、精度高,所设计控制器对系统模型参数摄动及外界扰动具有较强的鲁棒性.