Swing angle estimation for anti-sway overhead crane control using load cell

Overhead crane movement results in suspended load sway, which may cause dangers and damages. Common anti-sway methods are based on swing angle information. This paper presents a novel method that uses load cell sensors for swing angle estimation. According to our proposed method, a damping signal is generated and added to the speed reference in order to suppress the suspended load sway. Conventional methods of swing angle estimation are based on measurement by camera vision, acceleration, or some other type of sensor. Compared to conventional methods, the proposed method based on load cell is simpler to build and less sensitive to ambient conditions. The effectiveness of the method is verified by computer simulation.     

Optimal control of container cranes

A dynamical model of container cranes is derived by using Lagrange's equation. When a ship is loaded or unloaded with containers, the total motion of the container load is divided into five fundamental sections. For each fundamental type of motion, the optimal control is calculated such that the corresponding trajectory satisfies the specified boundary conditions and that the swing of the container load during the transfer is minimized. A new algorithm which is employed for computing the optimal control is explained in detail. Some results of numerical computation are also shown.     

Second-order sliding-mode control of container cranes

Moving a suspended load along a pre-specified path is not an easy task when strict specifications on the swing angle and on the transfer time need to be satisfied. Intuitively, minimizing the cycle time and the load swing are conflicting requirements, and their satisfaction requires proper control actions, especially if some uncertainties in the system dynamics are present. In this paper we propose a simple control scheme, based on second-order sliding modes, which guarantees a fast and precise load transfer and the swing suppression during the load movement, despite of model uncertainties and unmodeled dynamic actuators. Such controller has been tested on a laboratory-size model of the crane, and some experimental results are reported.     

凿岩机器人钻臂GPC-PID双模控制

为避免广义预测控制(GPC)起始阶段存在因所获信息少而对双三角钻臂造成的控制不稳定,以及计算中因矩阵不可逆而造成的数值病态,提出以GPC和比例—积分—微分(PID)控制为基础的双模式自适应控制策略。根据广义预测PID算法得出在线更新的自校正参数,以此参数是否在规定范围内为依据判定采用PID控制模式或GPC模式。仿真结果表明:所提出的双模控制策略可以有效降低广义预测控制起始阶段的不稳定现象,提高运行中的跟踪效果,同时也能保证计算发生病态时钻臂控制的正常运行。     

Fuzzy sliding mode control of container cranes

A fuzzy sliding mode control strategy for container cranes is discussed in this paper. In which, the sway motion of a payload is integrated into the trolley dynamics in a sliding surface. This scheme guarantees the asymptotic stability of the closed-loop system. Moreover, the control gain, which is the most important component, is a flexible gain and is tuned based on fuzzy laws to avoid chattering phenomena of the system. The performance of the closed-loop system has been simulated using MATLAB. In addition, to illustrate the efficiency of the proposed control law, experimental results are also provided.     

舞台调速吊杆群同步控制策略研究与仿真

提出了基于内模与模糊PID混合的多电机同步控制策略。将内模控制器引入速度并联同步控制系统,将其取代常规PI速度跟踪控制器,以其较强的鲁棒性来抑制系统参数摄动及负载扰动等不确定因素造成的不同步现象;同时结合现代智能控制技术,将专家的控制经验及推理过程融入系统当中,设计了模糊PID同步补偿器,从而实现了多电机的高精度同步控制。     

Overhead cranes fuzzy control design with deadzone compensation

This article proposes a simple but effective way to control 3D overhead crane. The proposed method uses PID control at the start for rapid transportation and fuzzy control with deadzone compensation when the crane is close to the goal for precise positioning and moving the load smoothly. Only the remaining distance and projection of swing angle are applied to design the fuzzy controller. No plant information of crane is necessary in this approach. Therefore, the proposed method greatly reduces the computational efforts. Several experiments illustrated the encouraging effectiveness of the proposed method through a scaled 3D crane model. The nonlinear disturbance, such as abrupt collision, is also taken into account to check the robustness of the proposed method.     

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.     

悬臂式掘进机自动控制系统设计

针对目前悬臂式掘进机机身定位存在精度低、自动化控制性能差和工作效率低等问题,设计了悬臂式掘进机自动控制系统,详细介绍了系统硬件、软件的设计。该系统采用姿态检测技术和自动截割技术,实现了对悬臂式掘进机的精确截割与自动控制。     

Application of intelligent sliding mode control with moving sliding surface for overhead cranes

In this paper, neural-based fuzzy logic sliding mode control with moving sliding surface has been designed for supervision of an overhead crane. A mathematical model has been established of the crane, and equations of motion have been obtained. First, the suitable sliding surface coefficient has been determined for the fixed sliding surface in the design of sliding mode control. The sliding surface has been moved by using neural-based fuzzy logic algorithm to eliminate disadvantage of the regular sliding mode control. By application of this control algorithm, the control performance incredibly increased. In the application, during the carriage of the load to a target which was 1 m away by a crane with 3 kg of load and 100 cm of rope length, the parameters of effected controllers were updated and their training was realized. In order to display the insensitiveness of the controller to parametric uncertainty, the value of the load was taken as 8 kg and the length of the rope was taken as 3 m and controls for a different target were realized. MATLAB program was used for numerical solutions, and results were examined graphically. Obtained results displayed the success of the algorithm of neural-based fuzzy logic sliding mode control.     

Tracking control for an object in pushing operation

In this paper, we consider the problem of making a manipulator push an object on a flat floor with a point of contact to a desired position. A manipulator control method for the object to follow a planned trajectory is proposed. First, using the given distribution of frictional forces between the object and the floor, we find a particular point, named pseudo center, on which the motion of the pushed object can be approximated by the motion of a wheeled mobile robot on its center. Then, a control rule for the pushing operation is derived by applying a tracking control rule for a nonholonomic mobile robot at the pseudo center. This method makes it possible for the robot to perform the tracking control in the pushing operation. A simulation result shows the effectiveness of the proposed method. Finally, we present an approach for using a mobile manipulator to realize the pushing operation. Experimental verification of the proposed method was performed and the result is described. ©1997 John Wiley & Sons, Inc.     

PI control based on fuzzy set-point weighting tracking for hydraulic crane boom system

A PI control strategy based on fuzzy set-point weighting following was proposed for the active damping control of a hydraulic crane boom system （HCBS）. Two valve-controlled PI controllers, which include a proportional feedforward controller based on fuzzy set-point weighting following and a limited semi-integrator（LSI）, are designed respectively. LSI is used to limit output signal and to prevent wind up at the low frequency of the spectrum. By using a range camera and an electronic feedback control, the tip damping on the HCBS can be adjusted artificially. A collaborative control simulation technique of HOPSAN and MATLAB/SIMULINK is applied to the controller design. Simulation results show that the proposed PI control system has less overshoot as well as faster response. The tip damping on the HCBS during operation is improved.     

Tracking and force control for a class of robotic manipulators

The increasing utilization of robotic manipulators in industrial tasks, such as assembly, forming or shaping of surfaces, and handling hazardous materials, depends greatly on available hybrid force and position control schemes. Since the robot and its environment are often subject to parameter uncertainties that cannot be neglected, it is necessary to design controllers that are robust with respect to these uncertainties. In addition, the dynamics of the robot are nonlinear, requiring consideration of nonlinear control concepts. Another aspect to be taken into account is the relative stiffness of the robot, the force sensor, and the manipulated surface. That is, the behavior of the system normal to the surface is relatively stiff, while that tangential to the surface is relatively free. Separation of the controller for these two directions is therefore indicated. We propose a controller design that accounts for this point of view and demonstrate its efficacy with respect to robustness and accuracy of position and force tracking by means of numerical simulations. The design is based on the control concept of Corless and Leitmann [l]. The example considered is a Manutecr3 robot with three degrees of freedom. In addition, we account for the dynamics of the actuator, which also possesses three degrees of freedom. The considered parameter uncertainties are friction moments in the links and friction between the end effector and the manipulated object, as well as nonlinear dynamics, which are difficult to characterize.Recommended by J. Skowronski     

悬臂式掘进机俯仰角调控系统仿真研究

目前掘进机俯仰角检测误差主要通过人工控制掘进机前铲板、后支撑来补偿,补偿范围十分有限,且效率低下,控制精度与自动化程度较低。针对该问题,建立了悬臂式掘进机俯仰角与执行机构数学模型,确定了通过PID控制器控制掘进机前铲板与后支撑液压缸位移实现掘进机位姿调整的方法;利用AMESim建立掘进机执行机构的完整液压模型,仿真结果表明,俯仰角调控系统响应时间小于3s,液压缸位移控制误差小于2mm,验证了系统的基本性能;Simulink仿真结果验证了俯仰角调控系统响应时间短、跟踪误差小,且具有较好的动态跟踪性能。     

Tracking control system using image sensor for arc welding

A highly accurate and widely applicable tracking control system which guides a welding torch along a joint line is described. The control system includes a servomechanism, a solid-state image sensor, and an image processor. The solid-state image sensor detects the cross-sectional pattern of the welding groove with a He-Ne gas laser. The image processor, consisting mainly of a microcomputer, processes video information and estimates the position of the welding groove center using a statistical technique. This method of tracking control has been employed in the welding apparatus for penstocks with good practical results.     

Tracking control of a rolling disk

The tracking control of a disk rolling without slipping on the horizontal (X, Y)-plane is considered. The motion of the disk can be controlled via a tilting torque and a pedaling torque. The concept of path controllability of the disk is introduced and then used to calculate control laws such that the disk tracks a given path in the (X, Y)-plane     

Tracking control for multi-agent consensus with an active leader and variable topology

In this paper, we consider a multi-agent consensus problem with an active leader and variable interconnection topology. The state of the considered leader not only keeps changing but also may not be measured. To track such a leader, a neighbor-based local controller together with a neighbor-based state-estimation rule is given for each autonomous agent. Then we prove that, with the proposed control scheme, each agent can follow the leader if the (acceleration) input of the active leader is known, and the tracking error is estimated if the input of the leader is unknown.