模糊切换增益调节下非线性系统的滑模控制

本文运用模糊控制和滑模控制相结合的方法对一类不确定非线性系统进行了深入研究。针对动态方程中控制系数与状态变量和时间变量有关的非线性时变系统,设计了带有状态变量和时间变量的新的模糊切换增益调节滑模控制器,给出了新的模糊滑模控制律,并证明了系统的稳定性。考虑到外部干扰是影响所研究系统稳定性的重要因素,本文运用调节模糊切换增益的技术,实现了对不确定外界扰动项的补偿。采用全局滑模面技术设计了滑模控制器,成功地避免了传统变结构控制器在到达阶段对不确定性的敏感性,增强了系统的鲁棒性。通过实例仿真,验证了本文所提出的控制方法不仅能够保证所研究的非线性系统是稳定的,还能够有效消除系统的抖振。     

虚拟锚泊神经网络模糊滑模控制器的设计

针对虚拟锚泊浮标在目标点位置难以进行锚泊的问题,设计了一种神经网络模糊滑模控制器。通过引入虚拟锚泊圆,将在锚泊点一定范围内虚拟锚泊的问题转变为对虚拟锚泊圆进行路径跟踪的问题,应用Fossen矩阵建立虚拟锚泊浮标动力学模型,采用Serret-Frenet坐标变换和重新定义输出变量,将单输入多输出非线性系统转变为单输入单输出非线性系统,进而构建滑模控制器,采用模糊算法对滑模开关量进行在线调整,削弱滑模控制器的"抖振",采用神经网络对滑模控制器进行优化,摆脱对系统模型的依赖性,提高控制器的鲁棒性,并对该控制器进行仿真实验和分析,结果表明该控制器具有很好的虚拟锚泊性能。     

含有控制时滞的多输入离散系统的变结构控制

给出了多输入离散系统的基于时变衰减幂次趋近律的滑模变结构控制方法,并通过时滞变换将结果推广到含有控制时滞的情形。首先选取具有适当增益矩阵的线性切换函数以保证系统在切换面上的理想准滑模运动方程的极点可任意配置。其次基于时变衰减幂次趋近律设计了准滑模控制器,该控制器能够保证两类离散系统的运动轨迹在有限时间内到达准滑模带,然后要么直接转入理想准滑模,要么在准滑模带中以指数幂速率快速趋于理想准滑模,并使系统的运动轨迹能够渐近趋于状态空间的原点,而不再是原点附近某邻域中出现稳定抖振。最后的仿真结果进一步表明了这种方法的有效性。     

一类时滞不确定随机Markovian跳变系统的滑模控制

研究一类时滞不确定随机Markovian跳变系统的滑模控制问题。首先,给出了由有限维状态空间中齐次Mar-kovian过程产生的跳跃参数,利用次可达的概念,给出了该系统的状态轨线逼近确定滑模面的条件;其次,设计了滑模变结构控制器,保证系统运动到达滑模是次可达的,并且给出了系统滑动运动为均方渐近稳定的充分条件;最后,通过仿真例子说明了本文方法的可行性与有效性。     

基于扰动观测器的非奇异模糊滑模无人船编队控制

针对含有模型参数不确定性、外界干扰与抖振现象的无人船编队问题，提出了一种基于扰动观测器的非奇异模糊终端滑模编队控制方法。首先，将领航者–跟随者与人工势场法相结合，获得无人船的编队构型并保证无碰撞现象；其次，基于 Lyapunov 能量函数设计出模糊控制规则，消除了控制器中的抖振问题； 进而，提出了一种扰动观测器来补偿未知动态和外界干扰，增强了系统的鲁棒性和稳定性。通过理论分析和仿真结果验证了所提控制方法的有效性。基于所设计的编队控制方法，无人船最终可形成期望的编队构型。     

海底管线检修潜水器垂直面控制及自航模试验

论述了纵倾控制律设计及自航模试验。首先选择一系列深度,对同一深度采用频域校正法单独设计控制律,使之对不同的速度和漂角具有足够的稳态精度和抗干扰性,这些控制律被集成统一为纵倾控制器,并根据潜深变化进行切换,对于其它深度采用同样的方法设计。控制器首先通过计算机仿真,然后进行自航模试验验证。设计的纵倾控制系统同时在其他试验项目中(水下管线跟踪和动力定位)发挥了重要的作用。     

大深度载人潜水器浮力材料的应用现状和发展趋势

在所有海洋装备中,大深度载人潜水器代表深海技术的制高点,而大深度载人潜水器的研制所要解决的关键问题之一就是浮力材料的选择。文章概述浮力材料的分类以及浮力材料在三代大深度载人潜水器上的应用情况,并对能够满足大深度尤其是全海深载人潜水器需求的浮力材料进行对比研究。研究结果表明:微珠复合泡沫虽然能满足7 000m载人潜水器的需求,但应用在全海深载人潜水器时存在密度大和吸水率高的缺点,且不能满足1.5倍安全压力要求;陶瓷等新型浮力材料的密度小和吸水率低,是未来浮力材料的重要发展方向。本研究可为大深度载人潜水器浮力材料的选择提供一定的理论支持。     

基于改进Super-Twisting滑模与干扰观测器AUV控制方法

以X 舵智能水下机器人(Autonomous Underwater Vehicle,AUV)为研究对象,提出了一种改进 Super-Twisting 滑模与非线性干扰观测器结合的 AUV 控制方法。首先,对 AUV 进行了运动学、动力学以及 X 舵分配进行了建模;之后,按照 Super-Twisting 理论设计了 AUV 控制器;然后,考虑到原算法中符号函数引起的控制输出抖振现象,提出了基于 Sigmoid 函数的改进 Super-Twisting 控制器,考虑到未建模动态以及外部环境干扰,设计了非线性干扰观测器对集总干扰进行补偿;最后,通过仿真验证了所提控制器的有效性。仿真表明,在干扰影响条件下,所提方法能够在大幅降低输出抖振并保证良好的控制精度。     

水下机器人-机械臂系统的滑模自抗扰控制

针对水下机器人机械臂系统的强耦合、强非线性、复杂海洋多源干扰等因素影响，提出了滑模自抗扰控制器，将复杂系统模型转变为简单的积分串联系统，将内部参数不确定性、测量误差、建模误差和海洋多源干扰等扰动归结为总扰动，并采用线性扩张观测器对其进行估计并抵消。利用滑模控制器提高系统对参数摄动的不敏感性，增强控制系统的抗干扰性能，通过李雅普诺夫理论分析了控制系统的有界稳定性。仿真结果表明滑模自抗扰与传统滑模控制和自抗扰控制相比，能使水下机器人机械臂实现更好的轨迹跟踪，且系统具有更好的抗干扰能力。     

开架式水下机器人运动的模糊非线性PD控制方法

由于水下机器人系统的非线性动力学特性和工作环境的复杂性和不确定性,如何更好地设计水下机器人作业时的运动控制器一直是其实用化过程中没能得到很好解决的问题。结合模糊逻辑和S面控制,利用T—S推理结构,设计了一种兼具局部和全局调整功能的模糊非线性PD(m)控制器,仿真结果表明,其控制效果要优于采用单一控制参数的S面控制器。     

Design of a sliding mode fuzzy controller for the guidance and control of an autonomous underwater vehicle

This work demonstrates the feasibility of applying a sliding mode fuzzy controller to motion control and line of sight guidance of an autonomous underwater vehicle. The design method of the sliding mode fuzzy controller offers a systematical means of constructing a set of shrinking-span and dilating-span membership functions for the controller. Stability and robustness of the control system are guaranteed by properly selecting the shrinking and dilating factors of the fuzzy membership functions. Control parameters selected for a testbed vehicle, AUV-HM1, are evaluated through tank and field experiments. Experimental results indicate the effectiveness of the proposed controller in dealing with model uncertainties, non-linearities of the vehicle dynamics, and environmental disturbances caused by ocean currents and waves.     

Path Following Control of A Deep-Sea Manned Submersible Based upon NTSM

In this paper, a robust path following control law is proposed for a deep-sea manned submersible maneuvering along a predeterminated path. Developed in China, the submersible is underactuated in the horizontal plane in that it is actuated by two perpendicular thrusts in this plane. The advanced non-singular terminal sliding mode （NTSM） is implemented for the design of the path following controller, which can ensure the convergence of the motion system in finite time and improve its robustness against parametric uncertainties and environmental disturbances. In the process of controller design, the close-loop stability is considered and proved by Lyapunov＇ s stability theory. With the experimental data, numerical simulations are provided to verify the control law for path following of the deep-sea manned submersible.     

Information fusion model-free adaptive control algorithm and unmanned surface vehicle heading control

Based on the model-free adaptive control (MFAC) theory, the heading control problem of unmanned surface vehicles (USVs) with uncertainties is explored. First, as a USV’s heading subsystem does not satisfy the quasilinear assumption of the MFAC theory, a new type of input and output information fusion MFAC, i.e., the IOIF–MFAC algorithm is proposed. The novel algorithm proposed herein renders the MFAC theory applicable to the heading control of USVs. Next, the input and output information of the heading subsystem, namely the rudder angle and heading angle, are combined, and the data model of the heading subsystem is subsequently deduced using a compact format dynamic linearization method. Based on which, the stability of the control system is proved. Finally, the effectiveness and practicability of the IOIF–MFAC algorithm are verified by simulation and field experiments through the “Dolphin IB” test platform developed by our group.     

基于模糊PID的深海采矿机器人路径跟踪控制

深海采矿作业中,由于海底软泥稀软,采矿机器人极易打滑,以及海底地形、海流等干扰,采矿机器人容易偏离预定路径。针对采矿机器人的海底作业过程中路径跟踪问题,设计并分析了深海采矿机器人的路径跟踪控制系统。首先提出了艏向控制实现采矿机器人路径跟踪的控制算法,通过采矿机器人与当前目标点相对位置计算采矿机器人的目标艏向角,后基于运动学模型建立模糊比例积分微分(PID)的控制方法控制采矿机器人两侧转速差值进而控制采矿机器人艏向,从而使机器人按目标路径行走;同时为了防止输入过大引起打滑,基于动力学模型数值分析了采矿机器人主动轮角加速度与打滑率之间的关系,采取限制主动轮角加速度方式防止采矿机器人过度打滑;最后通过Matlab/Simulink建立系统模型对系统进行仿真分析。仿真结果表明,该控制算法能够良好地完成采矿机器人的路径跟踪任务。     

The nonlinear hydrodynamic model for simulating a ship steering in waves with autopilot system

In the paper, a hydrodynamic numerical model including wave effect is developed to simulate ship autopilot systems by using the time domain analysis. The PD controller and the sliding mode controller are adopted as the autopilot systems. The differences of simulation results between two controllers are analyzed by cost function composed of heading angle error and rudder deflection, either in calm water or in waves. The results in calm water show that both controllers are tracking well for the desired route with the similar cost function value by tuning the key design parameters. However, the course tracking ability of the controller using sliding mode in waves is generally better even the cost function value is similar.     

Robust adaptive control of underactuated ships on a linear course with comfort

This paper addresses an important problem in ship control application—the robust stabilization of underactuated ships on a linear course with comfort. Specifically, we develop a multivariable controller to stabilize ocean surface ships without a sway actuator on a linear course and to reduce roll and pitch simultaneously. The controller adapts to unknown parameters of the ship and constant environmental disturbances induced by wave, ocean current and wind. It is also robust to time-varying environmental disturbances, time-varying change in ship parameters and other motions of the ship such as surge and heave. The roll and pitch can be made arbitrarily small while the heading angle and sway are kept to be in reasonably small bounds. The controller development is based on Lyapunov’s direct method and backstepping technique. A Lipschitz continuous projection algorithm is used to update the estimate of the unknown parameters to avoid the parameters’ drift due to time-varying environmental disturbances. Simulations on a full-scale catamaran illustrate the effectiveness of our proposed controller.     

An assessment of fuzzy logic vessel path control

A fuzzy logic controller for ship path control in restricted waters is developed and evaluated. The controller uses inputs of heading, yaw rate, and lateral offset from the nominal track to produce a commanded rudder angle. Input variable fuzzification, fuzzy associative memory rules, and output set defuzzification are described. Two maneuvering situations are evaluated: track keeping along a specified path where linearized regulator control is valid; and larger maneuvers onto a specified path where nonlinear modeling and control are required. For the track keeping assessment, the controller is benchmarked against a conventional linear quadratic Gaussian (LQG) optimal controller and Kalman filter control system. The Kalman filter is used to produce the input state variable estimates for the fuzzy controller as well. An initial startup transient and regulator control performance with an external hydrodynamic disturbance are evaluated using linear model simulations of a crude oil tanker. A fully nonlinear maneuvering model for a smaller product tanker is used to assess the larger maneuvers     

Expanded adaptive fuzzy sliding mode controller using expert knowledge and fuzzy basis function expansion for UFV depth control

Generally, the underwater flight vehicle (UFV) depth control system operates with the following problems: it is a multi-input multi-output (MIMO) system, it requires robustness, a continuous control input, and further, it has the speed dependency of controller parameters. To solve these problems, an expanded adaptive fuzzy sliding mode controller (EAFSMC), which is based on the decomposition method designed by using an expert knowledge and the decoupled sub-controllers and composition method designed by using the fuzzy basis function expansions (FBFEs), is proposed. To verify the performance of the EAFSMC, the depth control of UFV in various operating conditions is performed. Simulation results show that the EAFSMC solves all problems experienced in the UFV depth control system online.     

海洋平台磁流变阻尼器控制技术研究

为了更有效地减小海洋平台动力响应,采用基于模糊控制算法的磁流变阻尼器对海洋平台的振动进行控制.以海洋平台位移响应误差和误差变化为输入变量,以最优控制力为输出变量,优化设计出模糊控制器.考虑实际磁流变阻尼器输出控制力上限存在限制,采用半主动控制算法计算接近于最优控制力的半主动控制力.以一固定式海洋平台为算例研究磁流变阻尼器的振动控制效果及其模糊性,仿真结果表明模糊磁流变控制器对于平台的振动可以实现非常有效的控制,且控制效果对结构阻尼和环境的不确定性具有较好的模糊性.     

A task-based hierarchical control strategy for autonomous motion of an unmanned surface vehicle swarm

In this paper, a hierarchical control framework with relevant algorithms is proposed to achieve autonomous navigation for an underactuated unmanned surface vehicle (USV) swarm. In order to implement automatic target tracking, obstacle avoidance and avoid collisions between group members, the control framework is divided into three layers based on task assignments: flocking strategy design, motion planning and control input design. The flocking strategy design transmits some basic orders to swarm members. Motion planning applies the potential function method and then improves it; thus, the issue of autonomous control is transformed into one of designing the velocity vector. In the last layer, the control inputs (surge force and yaw moment) are designed using the sliding mode method, and the problem of underactuation is handled synchronously. The proposed closed-loop controller is shown to be semi-asymptotically stable by applying Lyapunov stability theory, and the effectiveness of the proposed methodology is demonstrated via numeric simulations of a homogeneous USV swarm.