Positioning of small-waterplane-area marine constructions with roll and pitch damping

In dynamic positioning systems for floating marine constructions a three-degrees-of-freedom multivariable controller, with feedback from the horizontal-plane positions and velocities in surge, sway and yaw, has been regarded as adequate for the control objective. However, for certain marine constructions with discernible coupling characteristics in the dynamics and kinematics between the horizontal-plane and the vertical-plane, undesirably large roll and pitch oscillations may be induced by the thruster actions applying the conventional horizontal-plane control strategy. In this paper a new multivariable control law accounting for both horizontal and vertical motions is proposed. It is shown that significant roll-pitch damping can be achieved. Moreover, the positioning performance in surge, sway and yaw is also improved because of suppressed roll-and pitch-induced horizontal-plane motions.     

Robust Tracking Control of a Quadrotor Helicopter

In this paper, a robust tracking control method for automatic take-off, trajectory tracking, and landing of a quadrotor helicopter is presented. The designed controller includes two parts: a position controller and an attitude controller. The position controller is designed by the static feedback control method to track the desired trajectory of the altitude and produce the desired angles for pitch and roll angles. By combining the proportional-derivative (PD) control method and the robust compensating technique, the attitude controller is designed to track the desired pitch and roll angles and stabilize the yaw angle. It is proven that the attitude tracking error of each channel can converge to the given neighborhood of the origin ultimately. Experimental results demonstrate the effectiveness of the designed control method.     

Control of marine riser end angles by position mooring

For safe drilling and work-over operations on floating platform, one objective is to minimize the rigid riser angles at the well-head and at the top joint. One way to achieve this is to control the vessel’s position. For shallow water, drilling operations are normally carried out using a moored vessel. In this paper, a system consisting of a vessel, mooring lines and a drilling riser was mathematically modelled. The strategy was to control the vessel’s position by changing the tensions in the mooring lines to ensure that the riser end angles are within safe limits. Numerical simulations and experiments of a moored vessel were performed to illustrate the feasibility of the proposed control strategy.     

Design of hybrid controller for dynamic positioning from calm to extreme sea conditions

High-level control of dynamic positioning systems on marine vessels using hybrid controller is developed to extend the operational weather window for marine operations to harsh environments. The types of hybrid controller considered are multi-output PID controllers with position measurements, and multi-output PID and acceleration feedback controllers with position and acceleration measurements. Numerical simulations and experiments in addition to stability proof are conducted to verify the proposed hybrid-controller dynamic positioning system in varying environmental conditions from calm to extreme seas.     

基于微分几何反馈线性化的高超声速飞行器控制系统实现

为实现对高超声速飞行器横滚角度数值、纵滚角度数值的同步控制,使飞行器元件呈现出相对平稳的运动状态,设计基于微分几何反馈线性化的高超声速飞行器控制系统;利用电源管理模块电路,更改电机驱动器元件的连接形式,根据螺旋桨转动速率,调试IMU惯性传感器、GPS定位、PID控制器三类下级硬件设备的实时运行状态,完成高超声速飞行器控制系统的主体应用结构设计;按照飞行器运动轨迹的微分处理结果,计算控制向量反馈指标的具体数值水平,再通过解析几何信号的处理方式,确定线性化姿态解算表达式,实现基于微分几何反馈线性化的飞行器控制程序设计,结合相关硬件应用设备,完成对高超声速飞行器控制系统的研究;实验结果显示,当实验时间为14 s时,实验组横滚角度数值与理想角度数值之间的差值最大为3°;当实验时间为6 s时,实验组纵滚角度数值与理想角度数值之间的差值最大为4°,微分几何反馈线性化原则能够有效控制横滚角度数值、纵滚角度数值与理想角度数值之间的差值水平,在促进高超声速飞行器平稳运动方面具有较强的可行性价值。     

Dynamic positioning of drilling vessels with a fuzzy logic controller

A fuzzy logic controller for dynamic positioning of drilling vessels in deep water is presented. The core of the fuzzy controller is a set of fuzzy associative memory (FAM) rules that correlate each group of fuzzy control input sets to a fuzzy control output set. A FAM rule is a logical if-then-type statement based on one's sense of realism and experience or can be provided by an expert operator. The design of the fuzzy controller is very simple and does not require mathematical modelling of the complicated nonlinear system based on first principles. The fuzzy controller uses measured vessel heading, yaw rate, distance and velocity of the vessel relative to the desired position (location and heading) to generate the control outputs to bring the vessel to and maintain it in the desired position. The control outputs include the rudder angle, propeller thrust and lateral bow thrust. The effectiveness and robustness of the fuzzy controller are demonstrated through numerical time-domain simulations of the dynamic positioning of a drill ship of Mariner Class hull with use of nonlinear ship equations of motions.     

基于逆系统方法的内模控制在吊车消摆运动中的应用

针对非线性、欠驱动的桥式吊车水平运动系统，先运用非线性逆系统方法将其转化为伪线性系统，然后按照线性系统理论设计内模控制器来控制吊车的水平定位．同时设计了一个角度反馈控制器来确保摆角迅速衰减．最后和常规PID、模糊控制做了比较．实验结果表明，本方案能保证定位无静差、摆角迅速衰减，同时具有良好的抗干扰能力和较强的鲁棒性，控制效果优于PID和模糊控制．     

Stabilization of the PVTOL aircraft based on a sliding mode and a saturation function

This study presents a feedback control strategy for the regulation of a planar vertical takeoff and landing aircraft. To this end, two controllers that work simultaneously were designed. The first controller is devoted to stabilizing the vertical variable and is based on a simple feedback‐linearization procedure in combination with a saturation function. The second controller – based on a combination of the traditionally PD‐controller and a sliding mode controller – stabilizes both the horizontal and angular variables to the desired rest position. The performance of the closed‐loop system is demonstrated through simulation results. Copyright © 2016 John Wiley & Sons, Ltd.     

基于改进主从控制结构的海洋机器人零航速减摇鳍系统

利用零航速减摇鳍系统实现对海洋机器人在近水面低速航行时的横摇姿态控制. 基于零航速减摇鳍的非线 性动态特性和海洋机器人横摇解耦模型, 提出具有主从结构的横摇减摇控制规律. 设计具有积分滑模面的变结构控 制规律, 估算系统期望横摇扶正力矩, 并进一步结合非线性跟踪控制理论和反馈线性化方法, 建立减摇鳍子系统模 型, 设计从属控制规律驱动减摇鳍产生实际横摇稳定力矩. 仿真结果和理论分析表明, 所设计的控制规律是稳定且有 效的.

     

基于级联方法的欠驱动AUV全局K指数3 维直线跟踪控制

采用非线性系统级联方法,提出一种欠驱动自主水下航行器的3维直线跟踪控制算法,首先将3维直线跟踪误差模型分解为水平面运动受垂直面运动扰动的级联结构;然后分别设计俯仰角指令和航向角指令,进一步将平面直线跟踪模型分解为位置跟踪误差受俯仰角/航向角跟踪误差扰动的级联结构,并设计了俯仰角和航向角的跟踪控制律,通过逐级应用级联系统稳定性理论证明了3维直线跟踪误差的全局κ指数稳定性;最后通过数学仿真验证了所提出跟踪控制算法的有效性。     

Robust Stabilization of Nonlinear PVTOL Aircraft with Parameter Uncertainties

In this work, the stabilization control problem is investigated for the planar vertical take‐off and landing (PVTOL) aircraft with unknown model parameters. To cope with the challenges caused by non‐minimum phase and parametric uncertainties, a new appropriate output, different from the general centroid position output, is carefully constructed to ensure the zero dynamics asymptotically stable, then the sliding‐mode technique is applied to design a state feedback control law. The proposed robust control law is proved able to asymptotically stabilize the PVTOL aircraft to the desired fixed position with null velocities and roll angle despite the unknown model parameters. Simulation examples illustrate the effectiveness of the proposed control algorithm.     

Tracking control for VTOL aircraft with disabled IMUs

This article focuses on the design of an output feedback controller able to achieve the asymptotic tracking of a reference trajectory for vertical take off and landing aircraft with disabled inertial measurement units (IMUs). Roll angle and roll rate cannot be measured directly when IMUs are disabled. A dynamic linear observer is designed to estimate the tracking errors of the roll angle and equivalent roll angular velocity with respect to their desired states. Moreover, based on the centre manifold theory and on the equivalent control, the closed-loop system is asymptotically convergent. The theoretical results are confirmed by computer simulations.     

基于自适应模糊PID的UCAV姿态控制

针对UCAV刚体六自由度模型非线性强耦合的特点,结合专家经验设计了一种自适应模糊PID姿态控制方法。利用小扰动原理对UCAV非线性模型线性化,得到了纵向和横侧向通道的状态空间表达式,实现了纵向和横侧向通道的解耦。针对纵向通道的俯仰角和速度以及横侧向通道的滚转角对设计的自适应模糊PID控制器进行了仿真验证,结果表明该控制器具有较快的响应速度和较高的稳定性,能够有效控制UCAV实现预期姿态。     

Adaptive back-stepping pitch angle control for wind turbine based on a new electro-hydraulic pitch system

A new electro-hydraulic pitch system is proposed to smooth the output power and drive-train torque fluctuations for wind turbine. This new pitch system employs a servo-valve-controlled hydraulic motor to enhance pitch control performances. This pitch system is represented by a state-space model with parametric uncertainties and nonlinearities. An adaptive back-stepping pitch angle controller is synthesised based on this state-space model to accurately achieve the desired pitch angle control regardless of such uncertainties and nonlinearities. This pitch angle controller includes a back-stepping procedure and an adaption law to deal with such uncertainties and nonlinearities and hence to improve the final pitch control performances. The proposed pitch system and the designed pitch angle controller have been validated for achievable and efficient power and torque regulation performances by comparative experimental results under various operating conditions.     

H∞ position transfer and regulation for floating offshore wind turbines

This paper proposes ${\rm H}_\infty$ controller design for platform position transfer and regulation of floating offshore wind turbines. The platform movability of floating wind turbines can be utilized in mitigating the wake effect in the wind farm, thereby maximizing the wind farm''s total power capture and efficiency. The controller is designed so that aerodynamic force is adjusted to meet the three objectives simultaneously, that is, 1) to generate the desired electrical power level, 2) to achieve the desired platform position, and 3) to suppress the platform oscillation. To acquire sufficient aerodynamic force to move the heavy platform, the pitch-to-stall blade pitching strategy is taken instead of the commonly-used pitch-to-feather strategy. The desired power level is attained by the standard constant-power strategy for the generator torque, while ${\rm H}_\infty$ state-feedback control of blade pitch and nacelle yaw angles is adopted for the position regulation and platform oscillation suppression. Weighting constants for the ${\rm H}_\infty$ controller design are adjusted to take the trade-off between the position regulation accuracy and the platform motion reduction. To demonstrate the efficiency of the proposed controller, a virtual 5-MW semi-submersible wind turbine is considered. Simulation results show that the designed ${\rm H}_\infty$ controller successfully accomplishes the platform position transfer and regulation as well as the platform oscillation reduction against wind and wave disturbances, and that it outperforms a previously-proposed linear quadratic controller with an integrator.     

Energy shaping control of an inverted flexible pendulum fixed to a cart

Control of compliant mechanical systems is increasingly being researched for several applications including flexible link robots and ultra-precision positioning systems. The control problem in these systems is challenging, especially with gravity coupling and large deformations, because of inherent underactuation and the combination of lumped and distributed parameters of a nonlinear system. In this paper we consider an ultra-flexible inverted pendulum on a cart and propose a new nonlinear energy shaping controller to keep the pendulum at the upward position with the cart stopped at a desired location. The design is based on a model, obtained via the constrained Lagrange formulation, which previously has been validated experimentally. The controller design consists of a partial feedback linearization step followed by a standard PID controller acting on two passive outputs. Boundedness of all signals and (local) asymptotic stability of the desired equilibrium is theoretically established. Simulations and experimental evidence assess the performance of the proposed controller.     

作业型水下机器人姿态调节控制研究

为了解决在作业时水下机器人载体上的机械手伸展过程将会引起载体重心发生变化,导致水下机器人发生纵横倾运动,影响作业效率的问题,考虑到水下机器人控制系统较为复杂,因此引入模糊滑模控制,根据要求设计出一款模糊滑模控制器。利用计算机和MATLAB技术,将水下机器人姿态运动方程与常规PID控制和模糊滑模控制分别结合起来进行仿真分析。仿真结果表明,模糊滑模控制相比于常规PID控制,在机械手关节正弦运动过程中,姿态角下降了20%以上,横倾姿态角度误差减小了30%以上,纵倾姿态角误差也超过了8%以上。在悬停作业过程中,纵横倾姿态角度都下降了30%以上。通过两种不同控制方式的仿真,验证了模糊滑模控制的控制效果要优于常规PID控制,能够取得更好的控制效果,同时利用计算机技术缩短了研究时间、提高了研究效率。     

Path‐Tracking Control of a Riderless Bicycle Via Road Preview and Speed Adaptation

In this study, a genetic‐fuzzy control system is used to control a riderless bicycle where control parameters can adapt to the speed change of the bicycle. The equations of motion are developed for a bicycle with constraints of rolling‐without‐slipping contact condition between the wheels and ground. This controller consists of two loops: the inner is a roll‐angle‐tracking controller which generates steering torque to control the roll angle while guaranteeing the stability, and the outer is a path‐tracking controller which generates the reference roll angle for the inner loop. The inner loop is a sliding‐mode controller (SMC) designed on the basis of a linear model obtained from a system identification process. By defining a stable sliding surface of error dynamics and an appropriate Lyapunov function, the bicycle can reach the roll‐angle reference in a finite time and follow that reference without chattering. The outer loop determines the proper reference roll‐angle by using a fuzzy‐logic controller (FLC) in which previewing and tracking errors are taken into consideration. The robustness of the proposed controller against speed change and external disturbances is verified by simulations.     

潜艇近水面低航速减摇的自适应神经元变结构控制

潜艇在近水面低航速航行时,为了有效克服波浪干扰力矩的作用,依据仿生翼减摇原理和变结构控制理论,在潜艇非线性模型基础上提出横摇控制器和纵摇控制器的设计方法.该方法以横摇角和纵摇角各自的偏差及其导数建立变结构控制切换面,选取相应的指数趋近律,计算了横摇和纵摇的变结构控制律.针对抖振现象,利用自适应神经元对趋近率进行在线修正.仿真结果表明,改进后的变结构控制提高了潜艇近水面低航速航行时的减摇控制性能.     

Quadrotor Control Via Robust Generalized Dynamic Inversion and Adaptive Non‐Singular Terminal Sliding Mode

A robust two‐loops structured control system design for quadrotor's position/attitude trajectory tracking is proposed. The aim of the outer loop is to provide the roll/pitch tilting commands to the inner loop, which in turns generates the tilting angles that control the quadrotor's center of gravity in the horizontal plane. The outer loop utilizes Robust Generalized Dynamic Inversion (RGDI) of a prescribed asymptotically stable differential equation in the deviation function of the horizontal position coordinates from their reference trajectories. The inner loop employs an Adaptive Non‐singular Terminal Sliding Mode (ANTSM) to control the tilting angles, in addition to controlling the yaw attitude angle and the vertical position coordinate. The proposed scheme solves the singularity avoidance problems of generalized inversion and terminal sliding mode control. The stability of outer and inner loop is ensured by utilizing positive definite Lyapunov energy function for stable tracking performance against parametric variations and bounded unknown external disturbances. Numerous simulations are conducted on a six Degrees of Freedom (DoF) quadrotor model in the presence of parametric variations, un modeled dynamics, and external disturbances.