A pure neural network controller for double‐pendulum crane anti‐sway control: Based on Lyapunov stability theory

Crane systems have been widely applied in logistics due to their efficiency of transportation. The parameters of a crane system may vary from each transport, therefore the anti‐sway controller should be designed to be insensitive to the variation of system parameters. In this paper, we focus on pure neural network adaptive tracking controller design issue that does not require the parameters of crane systems, i.e. the trolley mass, the payload mass, the cable lengths, and etc. The proposed neural network controller only requires the output feedback signals of the trolley, i.e. the position and the velocity, which means no sway measuring equipment is needed. The Lyapunov method is utilized to design the weights update law of neural network, and the robustness of the proposed controller is proved by the Lyapunov stability theory. The results of numerical simulations show that the proposed neural network controller has excellent performance of trolley position tracking and payload anti‐sway controlling.     

Analysis of the energy‐based swing‐up control for the double pendulum on a cart

Designing and analyzing controllers for mechanical systems with underactuation degree (difference between the number of degrees of freedom and that of inputs) greater than one is a challenging problem. In this paper, for the double pendulum on a cart, which has three degrees of freedom and only one control input, we study an unsolved problem of analyzing the energy‐based swing‐up control which aims at controlling the total mechanical energy of the cart‐double‐pendulum system, the velocity and displacement of the cart. Under the energy‐based controller, we show that for all initial states of the cart‐double‐pendulum system, the velocity and displacement of the cart converge to their desired values. Then, by using a property of the mechanical parameters of the double pendulum, we show that if the convergent value of the total mechanical energy is not equal to the potential energy at the up–up equilibrium point, where two links are in the upright position, then the system remains at the up–down, down–up, and down–down equilibrium points, where two links are in the upright–down, down–upright, and down–down positions, respectively. Moreover, we show that each of these three equilibrium points is strictly unstable in the closed‐loop system by showing that the Jacobian matrix valued at each equilibrium point has at least one eigenvalue in the open right half plane. This shows that for all initial states with the exception of a set of Lebesgue measure zero, the total mechanical energy converges to the potential energy at the up–up equilibrium point. This paper provides insight into the energy‐based control approach to mechanical systems with underactuation degree greater than one. Copyright © 2010 John Wiley & Sons, Ltd.     

面向大尺寸货物运送的吊车控制方法综述

随着现代化工业和基础设施建设的飞速发展,面向大尺寸货物运送的吊车系统以其高负载能力、低成本的显著优势广泛应用于集装箱搬运、风机安装、飞机机翼机身移动、水轮发电机转子安装、海上钻井平台搭建等诸多重要领域。然而,相对于传统的点质量单摆吊车系统,面向大尺寸货物运送的吊车系统具有更高的欠驱动程度、更强的状态耦合性和更加复杂的非线性,给大尺寸货物高效、安全的运送控制带来严峻挑战。本文首先简单阐述了面向大尺寸货物运送吊车系统不同吊装形式的建模、优势和缺点;然后,详细介绍了点质量双摆吊车系统、分布式质量双摆吊车系统和多吊车协同运送系统控制的研究现状;最后,对面向大尺寸货物运送吊车系统控制的研究现状进行概括,并对可能存在的关键问题和未来的研究方向进行了讨论和展望。     

环型二级倒立摆的控制研究与实现

通过分析环型二级倒立摆系统的动力学特性,将系统的状态空间方程在“倒立”的 平衡点附近进行线性化处理,应用线性二次型最优控制策略,对环型二级倒立摆进行控制器 的设计与仿真实验,并成功地将所设计的控制器应用到实际的环型二级倒立摆系统上,使其 稳定地平衡在“倒立”状态．所做应用与实际实验在国内尚未见到报道．     

A practical fuzzy controllers scheme of overhead crane

This paper presents fuzzy-based design for the control of overhead crane.Instead of analyzing the complex nonlinear crane system,the proposed approach uses simple but effective way to control the crane.There are twin fuzzy controllers which deal with the feedback information,the position of trolley crane and the swing angle of load,to suppress the sway and accelerate the speed when the crane transports the heavy load.This approach simplifies the designing procedure of crane controller;besides,the twin controller method reduces the rule number when fulfilling the fuzzy system.Finally,experimental results through the crane model demonstrate the effectiveness of the scheme.     

A practical fuzzy controllers scheme of overhead crane

1IntroductionThe overhead crane systemis widely usedinindustryformoving heavy cargos .Thus anti_sway and position controlhave become the requirements as a core technology forautomated crane systemthat are capable of flexible spatialautomatic conveyance .The purpose of crane control is to reduce the swing ofthe load while movingthe trolleyto the desired position asfast as possible .However ,the overhead crane has seriousproblems :the crane acceleration,required for motion,always induces undesir…     

小车二级摆摆起控制器设计

研究了小车二级并行摆系统及小车二级串行摆系统的摆起控制器设计问题,并给出了这两种系统的实验结果.首先,针对上述两种系统,设计了两步控制器,即1)摆起双摆达到倒立稳摆位置的控制器,2)进行稳摆控制的控制器.其次,由于小车二级摆位移受轨道长度限制,又考虑了小车位移的控制问题.上述两种实际系统的摆起及稳摆成功,验证了所提出设计方法的有效性.     

双摆机器人摆杆平衡态任意转换运动控制的实现

双摆机器人两摆杆具有一个自稳定(Down-down)和三个自不稳定(Down-up, up-down, up-up)的平衡状态, 4个平衡状态之间可以构成12个相互转换的运动动作和8个自旋动作. 本文运用基于动觉智能图式的仿人智能控制理论, 设计具有基于特征辨识多控制模态结构的控制器; 采用``类等效'的系统建模方法和改进型遗传算法, 实现双摆机器人模型的精确辨识和其多模态控制器多参数的整定与优化, 并解决了多控制模态之间的平滑切换, 以及从仿真研究到实时控制成功的快速过渡等关键问题. 以(Down-up)向(Up-down)状态的转换为例, 说明了如何实现四个平衡状态之间的任意相互转换的运动控制, 并介绍了仿人智能控制器设计的详细过程. 仿真与实时控制的实例证明了设计理论与方法的有效性.     

Payload pendulation and position control systems for an offshore container crane with adaptive‐gain sliding mode control

When container ports are not available for heavy ships, the offshore ship‐to‐ship transfer operation is an alternative method to an inland container terminal. This process is performed between a large container ship and a smaller ship, which is equipped with a container crane, called the mobile harbor or the ship‐mounted crane. The sea‐state condition is a crucial factor in open‐sea operations. The presence of waves, wind, and current disturbances excite the pendulum oscillations of the crane's hanging container. In this study, the problem of payload pendulation and container position for an offshore container crane using an adaptive‐gain sliding mode control (SMC) scheme is investigated. The primary control task during the loading and unloading process is to keep the container in the desired region under the harsh oceanic environment. The proposed control architecture incorporates an adaptive‐gain SMC with a compensation part and a prediction mechanism. Therein, a sliding surface is design to combine the desired sway motion of the payload with the desired trolley trajectory. Furthermore, a varying control gain is proposed in the sliding control, obtained by an adaption law that transitions the system into sliding mode. By constructing an appropriate Lyapunov function, we show that the proposed control law ensures the asymptotic stability of the ship‐mounted crane. Numerical simulations are presented to show the effectiveness and robustness of the proposed control system.     

多变量系统控制器的参数满意优化设计

为了将满意优化拓展到多变量系统中以解决多变量控制系统线性二次型(LQ)控制器设计中加权系数阵确定难的问题,提出多变量系统满意优化设计方法,通过设计满意度函数,构造出多变量系统的满意优化数学模型,并用改进遗传算法实现二级倒立摆系统LQ控制器满意优化设计.仿真结果显示,系统具有更满意的综合性能指标.证实了该方法的有效性和实用性.本文的研究对多变量系统优化设计具有一定的参考价值.     

Stabilization of the inverted spherical pendulum via Lyapunov approach

In this paper a nonlinear controller is presented for the stabilization of the spherical inverted pendulum system. The control strategy is based on the Lyapunov approach in conjunction with LaSalle's invariance principle. The proposed controller is able to bring the pendulum to the unstable upright equilibrium point with the position of the movable base at the origin. The obtained closed‐loop system has a very large domain of attraction, that can be as large as desired, for any initial position of the pendulum which lies above the horizontal plane. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Stabilization of the Furuta Pendulum with backlash using H∞‐LMI technique: experimental validation

The rotary inverted pendulum, also named Furuta Pendulum, has been studied extensively for control performance evaluation in under‐actuated mechanisms. The H_∞ control invoking linear matrix inequality (H_∞‐LMI) has been also widely employed for linear control design. This paper deals with the feasibility of the H_∞‐LMI technique to stabilize the rotary inverted pendulum around its unstable equilibrium point when there exists a backlash nonlinearity in the actuator. So, the H_∞‐LMI faces the nonlinear effect in the actuator and the non‐linear pendulum model. Experimental realization of the designed H_∞‐LMI control also shows evidence of the good performance of the controller subject to external perturbation. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Swing-up control strategies for a reaction wheel pendulum

Control of a reaction wheel pendulum, a prototype of an under-actuated system, is easily done using switching control strategies, which combines swing-up control and balancing control schemes. In this article, two novel swing-up control strategies for a reaction wheel pendulum have been proposed. The first swing-up control strategy treats the oscillations of the pendulum as perturbations from the bottom equilibrium point. The second swing-up control is based on interconnection and damping assignment-passivity based control (IDA-PBC). IDA-PBC preserves Euler Lagrangian structure of the system and gives more physical insight about any mechanical system. Any balancing controller can be coupled with the proposed swing-up control strategies to stabilise the pendulum at the top unstable equilibrium position. The control task of balancing the pendulum in top upright position is completed by switching from swing-up scheme to the balancing scheme at the point where the pendulum is very near to the top equilibrium point. Proposed swing-up control strategies have been implemented in real time in switching mode. The two proposed swing-up control schemes provide fast responses as compared to existing energy based schemes.     

基于Lyapunov能量函数的倒立摆稳定控制

倒立摆是一种复杂的非线性控制系统.通过对其进行控制能够检验控制器的鲁棒性.基于一个能量形式的Lyapunov函数设计了倒立摆稳定控制器使得摆趋于上平衡位置,并且使得小车位移和角度都收敛于零.该控制策略基于系统的总能量,利用其耗散特性设计了Lyapunov函数,并证明了控制系统的稳定性.理论分析及仿真试验表明该控制器对于倒立摆控制具有很强的鲁棒性.     

A crane-based five-axis manipulator for antenna tests

Antenna tests require precise positioning of an RF probe — at rest and during dynamic motions. Positioning includes the actual position of the tip of this probe and its vectorial orientation. This paper presents the automation and control concept for a novel crane-based measurement system. The system consists of a measurement gondola mounted to the hook of an overhead crane and designed such that it carries the probe and rotates it about two orthogonal axes. This system allows to arbitrarily position and orientate the probe in space on a given scanning surface. As the gondola is positioned using a crane, sway, skew, and tilting oscillations must be taken into account. Therefore a control concept is proposed that extends standard crane control by two additional degrees of freedom. For motion control with good trajectory tracking behavior, a flatness-based two-degree-of-freedom (2-DOF) state controller is applied for each axis. An extended Kalman filter is used for state estimation so that nonlinear effects and coupling between different axes are considered. The effectiveness of the proposed control concept is demonstrated by means of experimental results.     

双摆旋转起重机轨迹生成

虽然起重机系统的荷载摆动呈现出双摆特性比单摆特性更加接近于实际生产,但是,在这种情况下,系统特性分析和控制器的设计难度将大大增加.为此,本文提出一种基于S型曲线轨迹生成法实现旋转起重机两级残留摆角的抑制.首先根据拉格朗日运动方程推导出双摆旋转起重机的数学模型,再采用干扰观测器对该模型中的摩擦项、各子系统之间的耦合项进行补偿从而获得线性模型.由于各子系统中的一、二级摆角仍然是耦合的,因此采用模态分析对其进一步简化从而获得各自子系统的线性解耦模型.其次,分别为各子系统设计S型曲线轨迹,相关参数可通过求解代数方程获得.最后,数值仿真验证该方法的有效性.     

二级倒立摆的二次型最优控制研究

倒立摆系统以其自身的不稳定性而难以控制，也因此成为自动控制实验中验证控制策略优劣的极好的实验装置。针对二级倒立摆系统的平衡控制问题，对其进行数学建模，应用二次型最优控制理论设计了控制器。仿真结果表明，二次型最优控制对于典型非线性自不稳定系统有着很好的控制能力。     

Incremental Evolutionary Design of TSK Fuzzy Controllers

This paper proposes a novel method for the incremental design and optimization of first order Tagaki-Sugeno-Kang (TSK) fuzzy controllers by means of an evolutionary algorithm. Starting with a single linear control law, the controller structure is gradually refined during the evolution. Structural augmentation is intertwined with evolutionary adaptation of the additional parameters with the objective not only to improve the control performance but also to maximize the stability region of the nonlinear system. From the viewpoint of optimization the proposed method follows a divide-and-conquer approach. Additional rules and their parameters are introduced into the controller structure in a neutral fashion, such that the adaptations of the less complex controller in the previous stage are initially preserved. The proposed scheme is evaluated at the task of TSK fuzzy controller design for the upswing and stabilization of a rotational inverted pendulum. In the first case, the objective is a time optimal controller that upswings the pendulum in to the upper equilibrium point in shortest time. The stabilizing controller is designed as a state optimal controller. In a second application the optimization method is applied to the design of a fuzzy controller for vision-based mobile robot navigation. The results demonstrate that the incremental scheme generates solutions that are similar in control performance to pure parameter optimization of only the gains of a TSK system. Even more important, whereas direct optimization of control systems with more than 35 rules fails to identify a stabilizing control law, the incremental scheme optimizes fuzzy state-space partitions and gains for hundreds of rules.     

Swinging up the spherical pendulum via stabilization of its first integrals

This paper presents a new controller for swinging up the spherical pendulum. The problem of stabilizing the upright equilibrium of the spherical pendulum is typically solved in two steps: First, a controller is used to swing up the pendulum so that it enters some vicinity of the upright equilibrium, and then a locally stabilizing controller is used. The contribution of this paper is the design of a controller that solves the first subproblem for almost all initial conditions. The controller stabilizes the two-dimensional stable manifold of the hyperbolic upright equilibrium. The proposed technique is based on the passivity properties of the spherical pendulum.     

Design of optimized fuzzy cascade controllers by means of Hierarchical Fair Competition-based Genetic Algorithms

In this study, we present a design of an optimized fuzzy cascade controller based on Hierarchical Fair Competition-based Genetic Algorithms (HFCGA) for a rotary inverted pendulum system. In this system, one controls the movement of a pendulum through the adjustment of a rotating arm. The objective is to control the position of the rotating arm and to make the pendulum maintain the unstable equilibrium point at vertical position. To control the system, we design a fuzzy cascade controller scheme which consists of two fuzzy controllers arrange in a cascaded topology. The parameters of the controller are optimized by means of the HFCGA algorithm. The fuzzy cascade scheme comprises two controllers located in two loops. An inner loop controller governs the position of the rotating arm while an outer controller modifies a set point of the inner controller implied by the changes of the angle of pendulum. The HFCGA being a computationally effective scheme of the Parallel Genetic Algorithm (PGA) has been developed to eliminate an effect of premature convergence encountered in Serial Genetic Algorithms (SGA). It has emerged as an effective optimization vehicle to deal with very large search spaces. A comparative analysis involving computing simulations and practical experiment demonstrates that the proposed HFCGA based fuzzy cascade controller comes with superb performance in comparison with the conventional Linear Quadratic Regulator (LQR) controller as well as HFCGA-based PD cascade controller.