Combined control with sliding mode and partial feedback linearization for 3D overhead cranes

A 3D overhead crane is an underactuated system consisting of five outputs: trolley position, bridge translation, cable length, and two cargo swings. These outputs are controlled by three actuators for cargo hoisting, trolley motion, and bridge traveling. This study proposes the use of a nonlinear controller that performs five tasks concurrently: cargo hoisting, trolley tracking, bridge motion, payload vibration suppression during transport, and cargo swing elimination at the destination. The proposed algorithm is combined with two control components: (i) partial feedback linearization, which is a precursor to controller design, to suppress cargo vibration; and (ii) sliding mode method, which provides robust control in lifting the payload and driving trolley and bridge motions against model imprecision and uncertainty. These two control mechanisms are successfully merged into a combined controller because the kinematic relationships between the state variables are made apparent in the system dynamics. Simulation and experimental results show that the proposed controller asymptotically stabilizes all system responses.Copyright © 2013 John Wiley & Sons, Ltd.     

基于能量分析的桥式起重机防摆控制方法

针对欠驱动桥式起重机在自动化驾驶研究中负载升/落吊运动与台车水平位移联动时,负载摆动抑制效果和控制性能不能满足实际工程需要,易造成安全事故的问题,提出一种基于能量分析的桥式起重机联动系统非线性耦合防摆控制器.采用非线性耦合控制方法,构造新型储能函数,设计出非线性耦合防摆控制器.利用LaSalle不变性原理和Lyapunov方法对该闭环反馈系统稳定性进行严格的数学分析.理论推导、仿真与实验结果表明:相比于非线性跟踪控制器和局部反馈线性化控制器,所提非线性耦合防摆控制器具有更佳的控制性能,不仅提高了负载的吊运效率,而且能够有效抑制和快速消除负载摆角;在添加外部扰动的情况下,仍能取得良好的控制效果,具有较强的鲁棒性,为桥式起重机联动系统提供了一种新的防摆控制方法.     

Adaptive neural network hierarchical sliding mode control for six degrees of freedom overhead crane

This paper presents an effective control method for three-dimensional (3D) overhead cranes with six degrees of freedom (DOF). Two payload swings and an axial payload oscillation should be minimized besides driving the bridge, trolley, and hoisting drum to bring the payload to the desired position in space. First, a novel 3D-6DOF crane model is developed, where the sixth degree of freedom is axial cargo oscillation that has never been considered in previous studies. A controller is then designed using the hierarchical sliding mode control method. Moreover, a radial basis function neural network (RBFNN) is used to approximate the system's unknown dynamic model accurately. According to the Lyapunov principle, a control law and an updated law for the neural network's weight matrices are designed to ensure the stability of the closed-loop system. Simulation results on Matlab software show the proposed approach's effectiveness, such as smaller swing, minor axial oscillation, and precise position as desired.     

Nonlinear coupling tracking control for underactuated construction lifting robots with load hoisting/lowering under initial input saturations

Underactuated construction lifting robots, which have been widely concerned by erudite researchers, always contain load hoisting/lowering motion. When the cable length is utilized as a variable, construction lifting robots produce violent load swing, which affects the construction safety undoubtedly and brings great challenges to the development of the controller. Moreover, most existing controllers may not take into account issues, such as initial input saturations and poor ability to suppress load swing, and they may utilize linearization or approximation. Inspired by these phenomena, a nonlinear coupling tracking controller for underactuated construction lifting robots with load hoisting/lowering under initial input saturations is proposed. With reference to expected trajectories to ensure the smooth operation of the construction lifting robot system, the initial input saturations are considered to make the trolley and cable start stably, respectively; a coupling signal, which contains actuated variables and underactuated variables, is constructed to improve the transient control performance of construction lifting robots. Combined with theoretical derivation, simulation, and experimental verification, the proposed controller achieves superior control performance, which ensures the accurate positionings of the system, and suppresses and eliminates the load swing effectively, so as to ensure the safe construction; the proposed controller admits outstanding robustness with respect to the changes of system parameters and the adverse effects of external disturbances. The proposed controller provides a novel antiswing strategy for construction lifting robots with load hoisting/lowering, which possesses excellent practical significance.     

欠驱动桥式吊车消摆跟踪控制

对于桥式吊车系统而言,其控制目标是将货物快速、精确、摆动尽可能小地运送到目标位置.为此,本文提出了一种新型的轨迹跟踪控制策略,可在保证负载快速平稳运送的同时,有效地抑制并消除整个过程中负载的摆动.具体而言,通过对吊车动力学模型进行一系列的变换,设计了一种新颖的跟踪控制器,并对闭环系统信号的有界性与收敛性进行了理论分析.与调节控制方法相比,本文方法可保证台车的平滑启动与运行;此外,本方法放宽了已有轨迹跟踪控制方法对参考轨迹的约束条件,更具实用性与一般性.实验结果表明,本文设计的控制器能取得优于已有方法的控制效果,并对外界干扰具有很强的鲁棒性.     

A controller enabling precise positioning and sway reduction in bridge and gantry cranes

Precise manipulation of payloads is difficult with cranes. Oscillation can be induced into the lightly damped system by motion of the bridge or trolley, or from environmental disturbances. To address both sources of oscillation, a combined feedback and input shaping controller is developed. The controller is comprised of three distinct modules. A feedback module detects and compensates for positioning error; a second feedback module detects and rejects disturbances; input shaping is used in a third module to mitigate motion-induced oscillation. An accurate model of vector drive and AC induction motors, typical to large cranes, was used jointly with a deconvolution analysis technique to incorporate the nonlinear dynamics of crane actuators into the control design. The controller is implemented on a 10-ton bridge crane at the Georgia Institute of Technology. The controller achieves good positioning accuracy and significant sway reduction.     

An advanced cargo handling system operating at sea

Mobile Harbor (MH) was recently proposed by KAIST as a novel maritime cargo transfer system that can go out to a container ship anchored in deep water and handle containers at sea. Since the system operates in at-sea conditions with waves and wind, the MH crane should be designed to suppress the swing motion of a spreader and compensate the relative motion between the MH and a container ship. For that purpose, we devised a state-of-the-art crane system equipped with a dual stage trolley, tension controller, and intelligent spreader with 3 degrees of freedom. We also integrated a robust sensing system to measure remote motions in harsh open-sea condition. With these advanced systems, we achieved swing free, position, tilting, and heave control systems for precise and safe cargo transfer. Experimental results with a 1/20 scale MH crane show the feasibility of the proposed system for at-sea cargo transfer.     

An Energy-based Nonlinear Coupling Control for Offshore Ship-mounted Cranes

This paper proposes a novel nonlinear energy-based coupling control for an underactuated offshore ship-mounted crane, which guarantees both precise trolley positioning and payload swing suppressing performances under external sea wave disturbance. In addition to having such typical nonlinear underactuated property, as it is well known, an offshore ship-mounted crane also suffers from much unexpected persistent disturbances induced by sea waves or currents, which, essentially different from an overhead crane fixed on land, cause much difficulty in modeling and controller design. Inspired by the desire to achieve appropriate control performance against those challenging factors, in this paper, through carefully analyzing the inherent mechanism of the nonlinear dynamics, we first construct a new composite signal to enhance the coupling behavior of the trolley motion as well as the payload swing in the presence of ship′s roll motion disturbance. Based on which, an energy-based coupling control law is presented to achieve asymptotic stability of the crane control system′s equilibrium point. Without any linearization of the complex nonlinear dynamics, unlike traditional feedback controllers, the proposed control law takes a much simpler structure independent of the system parameters. To support the theoretical derivations and to further verify the actual control performance, Lyapunov-based mathematical analysis as well as numerical simulation/experimental results are carried out, which clarify the feasibility and superior performance of the proposed method over complicated disturbances.     

An Enhanced Coupling Nonlinear Tracking Controller for Underactuated 3D Overhead Crane Systems

An enhanced coupling nonlinear tracking control method for an underactuated 3D overhead crane systems is set forth in the present paper. The proposed tracking controller guarantees a smooth start for the trolley and solves the problem of the payload swing angle amplitude increasing as the transferring distance gets longer for the regulation control methods. Different from existing tracking control methods, the presented control approach has an improved transient performance. More specifically, by taking the operation experience, mathematical analysis of the overhead crane system, physical constraints, and operational efficiency into consideration, we first select two desired trajectories for the trolley. Then, a new storage function is constructed by the introduction of two new composite signals, which increases the coupling behaviour between the trolley movement and payload swing. Next, a novel tracking control strategy is designed according to the derivation form of the aforementioned storage function. Lyapunov techniques and Barbalat's Lemma are used to demonstrate the stability of the closed‐loop system without any approximation manipulations to the original nonlinear dynamics. Finally, some simulation and experiments are used to demonstrate the superior transient performance and strong robustness with respect to different cable lengths, payload masses, destinations, and external disturbances of the enhanced coupling nonlinear tracking control scheme.     

Dynamics modeling and control of large transport aircraft in heavy cargo extraction

In this paper,a novel version of six-degree-of-freedom nonlinear model for transport aircraft motion in cargo extraction is developed and validated by the theoretical mechanics and flight mechanics.In this model constraint force and moment reflecting the flight dynamic effects of inner moving cargo are formulated.A methodology for a control law design in this phase is presented,which linearizes the aircraft dynamics making use of piecewise linearization and utilizes robust control technique for interval system to achieve specified handling qualities with robustness to uncertainties.The simulations demonstrate adequate effectiveness and excellent robustness of the proposed controller.     

A new design approach for the anti-swing trajectory control of overhead cranes with high-speed hoisting

This paper proposes a new approach for the design of anti-swing control of overhead cranes. An anti-swing trajectory control scheme is designed based on the trolley and load-hoisting dynamics, and then extended to an adaptive scheme. The load-swing dynamics is controlled by employing a sliding surface that couples the load-swing dynamics with trolley motion. The number of degrees of freedom of the trolley and load-hoisting dynamics is the same as that of the control inputs; therefore, the control problem is reduced to finding a coupled sliding surface that stabilizes the crane control system, based on the load-swing dynamics. In this study, the Lyapunov stability theorem is used as a mathematical design tool. The proposed control guarantees asymptotic stability of the anti-swing trajectory control while keeping all internal signals bounded. The coupled sliding surface allows a direct control of the damping of load swing. In addition, the proposed control provides clear gain-tuning criteria for easy application. Finally, the proposed control realizes an anti-swing control along a typical anti-swing trajectory in practice, with high-speed load hoisting. The validity of the theoretical results is shown by computer simulation.     

LabSView平台下电动起吊推车控制系统设计

针对当前电动起吊推车控制方法,采用模糊人工控制准确定位和智能控制性不好的问题,在LabSView平台下进行电动起吊推车控制系统优化设计,提出基于多线程串口非线性严格反馈的电动起吊推车控制系统设计方法。控制系统分为硬件设计和软件设计两大部分,系统总体构架分为数据采集模块、控制陀螺仪模块、执行器模块、上位机通信模块和人机交互模块等,根据模糊PID控制律进行电动起吊推车控制算法设计,以ADSP-BF537作为主控芯片进行控制器硬件设计,在LabSView平台下进行控制算法程序加载,实现软件开发设计。系统测试结果表明,采用该系统进行电动起吊推车控制,灵敏度较高,控制收敛误差较低,鲁棒性较好。     

A New Adaptive Neuro-sliding Mode Control for Gantry Crane

This paper presents a new adaptive neuro-sliding mode control for gantry crane as varying rope length. This control method derived from combining the sliding surfaces of three subsystem of the gantry crane (trolley position, rope length, anti-swing) to draw out two system sliding surfaces: the trolley position with the anti-swing and the rope length and the anti-swing. On the based of the sliding mode control principle, drawn out the equivalent controller and the switching controller for gantry crane. But due to the uncertain parameters-nonlinear model of gantry crane with the bound disturbances, combining the neural approximate method, defined the neural controller and the compensation controller for the difference between the equivalent controller and the neural controller for two system control inputs: trolley position and rope length. The adaptive control laws for these controllers were deduced from Lyapunov’s stable criteria to asymptotically stabilize the sliding surfaces. Simulation studies are performed to illustrate the effectiveness of the proposed control.     

桥架起重机防晃控制非线性系统建模与研究

随着世界贸易的发展,桥架起重机发挥着越来越关键的作用;与此同时,桥架起重机防晃技术也日益受到关注。为分析桥架起重机系统的特性,为理论上验证与研究各种吊车控制方法的稳定性和效果提供参考,该模型在建立过程中考虑了电机对桥架起重机非线性系统的影响,对电机、小车和吊具与负载部分分别进行了分析、研究、建模与仿真,最终建立起桥架起重机防晃控制非线性系统完整的物理和数学模型,实现了对桥架起重机系统运动特性的完整描述。并用Matlab对电机、小车和吊具及负载部分,以及桥架起重机非线性系统的开环与闭环状态分别进行仿真,仿真结果验证了电机、小车、吊具及负载部分的特性,证明了模型的正确性,为研究桥架起重机防晃控制非线性系统提供了理论参考。     

A novel trajectory planning-based adaptive control method for 3-D overhead cranes

A three-dimensional (3-D) overhead crane is a complicated nonlinear underactuated mechanical system, for which high-speed positioning and anti-sway control are the kernel objective. Existing trajectory-based methods for 3-D overhead cranes focus on combining efficient and smooth trajectories with anti-sway tracking controllers without regard for payload motion; moreover, the exact value of plant parameters is required for accurate compensation during the control process. Motivated by these facts, we present a two-step design tracking strategy which consists of a trajectory planning stage and an adaptive tracking control design stage for 3-D overhead cranes. As shown by Lyapunov techniques and Barbalat's Lemma, the proposed controller guarantees asymptotic swing elimination and trolley positioning result in the presence of system uncertainties including unknown parameters and external disturbances. Simulation results also showed the applicability of the proposed method with good robustness against parameter uncertainties and external disturbances.     

基于自适应方法的桥式吊车的防摇定位控制器的设计

针对一类欠驱动非线性桥式吊车,设计了一种自适应控制器,它不需要对吊车模型进行近似解耦或线性化处理,不需要事先知道桥吊的精确的数学模型的参数信息,在负载质量等参数发生变化的情况下,能够实现对桥吊小车的精确定位与负载摆动的有效抑制,文中同时对该方法的稳定性进行了理论分析.该控制方法具有结构简单,计算量小的特点.数值仿真结果证实了本控制方法的良好效果.     

EMS型磁悬浮列车模块悬浮系统的模型参考自适应控制

模块是EMS型磁悬浮列车的基本功能单元,常用的悬浮控制方法是将其两端等效为两个完全独立的对象分别设计控制器。实际上模块两端的运动状态是互相耦合的,独立设计的控制器很难解决彼此之间的状态耦合。本文针对这种耦合情况,将模块视为一个刚体对象,采用反馈线性化方法实现模块运动的电气解耦,并针对模型的不确定性设计了模块悬浮系统的模型参考自适应控制器。仿真结果表明,该自适应控制器有效地解决耦合问题,提高悬浮系统的性能。     

Adaptive wave cancelation by acceleration feedback for ramp-connected air cushion-actuated surface effect ships

We solve the problem of cargo transfer in high sea states over a ramp from a large, medium-speed, roll-on/roll-off (LMSR) vessel to a smaller connector vessel of a surface effect ship (SES) type. Our aim is to reduce ramp motion between the LMSR and SES in order to provide a safer environment for cargo transfer. We design an air cushion actuated controller to estimate and cancel the wave disturbance and stabilize the heave of the SES via heave acceleration feedback with actuation of the louver area for the case where the hydrodynamic and other parameters of the SES are not known a priori and the pressure dynamics of the air cushion contains nonlinearly parameterized unknown terms. We demonstrate the effect of our control design in simulations in a time-domain seakeeping code, named AEGIR.     

考虑侧倾的无人车NMPC轨迹跟踪控制

针对高速行驶工况下,无人车转弯时的侧倾易导致车辆模型非线性程度增加,引起轨迹跟踪精度下降和状态失稳的问题,设计一种考虑车辆侧倾因素,基于非线性模型预测控制(NMPC)的无人车轨迹跟踪控制器.根据拉格朗日分析力学和车辆运动学,考虑车辆侧倾几何学和载荷转移效应,建立考虑侧倾因素的非线性车辆模型,包括车体动力学模型和修正的“Magic Formula”轮胎模型;基于此车辆模型,构建非线性模型预测控制器(NMPC)的预测模型,并设定控制器的线性、非线性约束,以保证车辆的运动状态处于稳定区域内.在Carsim和Simulink联合仿真平台上,验证车辆高速蛇形工况和双移线工况下的轨迹跟踪控制效果,仿真结果显示,所设计的控制器可有效改善高速弯道工况下的跟踪精度和车辆状态稳定性.     

起重机升降运动系统自适应Backstepping控制研究

通过分析起重机升降运动系统各组成部分的关联关系,建立了起重机升降运动系统数学模型,从而将电动机的运动状态和负载的运动状态有效地统一起来;以该模型为基础,将负载运动位置作为控制变量,采用自适应Backstepping控制策略设计了一种起重机升降运动系统负载位置控制器。仿真结果表明,该控制器具有较快的响应速度和较小的跟踪误差,能够有效抑制负载突变和参数摄动的影响,具有良好的鲁棒性。