Adaptive coupling control for overhead crane systems

Due to the requirements of high positioning accuracy, small swing angle, short transportation time, and high safety, both motion and stabilization control for an overhead crane system becomes an interesting issue in the field of control technology development. Since the overhead crane system is subject to underactuation with respect to the load sway dynamics, it is very hard to manipulate the crane system in a desired manner, namely, gantry position tracking and sway angle stabilization. Hence, in this paper, a nonlinear control scheme incorporating parameter adaptive mechanism is devised to ensure the overall closed-loop system stability. By applying the designed controller, the position error will be driven to zero while the sway angle is rapidly damped to achieve swing stabilization. Stability proof of the overall system is given in terms of Lyapunov concept. To demonstrate the effectiveness of the proposed controller, results for both computer simulation and experiments are also shown.     

Fuzzy motion control of an auto-warehousing crane system

Fuzzy motion control of an auto-warehousing crane system is presented in this paper. Using the concept of linguistic variable, a fuzzy logic controller (FLC) can convert the knowledge and experience of an expert into an automatic control strategy. The designed FLC with a rule base and three sets of parameters is used to control the crane system in x, y, and z directions. The unloaded weight and the fully loaded weight of the crane system in discussion are 1.35×10⁴ kg and 1.5×10⁴ kg, respectively. For various loading conditions and varying distances, the FLC still controls the crane system very well with positioning accuracy less than 2×10 ^-3 m for all directions. The distance-speed reference curve for control of the crane system is designed to meet the engineering specifications of motion such as acceleration, deceleration, maximum speed, and creep speed in each direction, and is generated automatically according to varying distance. The method for designing the distance-speed reference curve can make the crane move at relatively high speed to approach the target position. Simulations of the motion control in the three directions are demonstrated     

Scaling laws for coupling quantities on EMP

A set of scaling laws relating three-potential electromagnetic coupling quantities to three electromagnetic pulse (EMP) characteristics is derived. The electromagnetic coupling quantities are an attempt to characterize, in a very rough sense, the ability of an electromagnetic wave to induce an electronic upset in an electric circuit. The coupling quantities used are chosen based on voltage transients, power transients, and energy-induced overload as mechanisms for electronic upset. The independent quantities in the scaling laws are chosen to be the pulse rise time, peak field, and total energy density     

Reachable and stabilizable area of an underactuated manipulator without state feedback control

The reachable and stabilizable area of a two-link underactuated manipulator is clarified theoretically and experimentally. The manipulator consists of an active (first) link attached to an actuator and a free (second) link connected to the first link with a joint that lacks not only an actuator but also a sensor. In this circumstance the motion of the second (free) link can be controlled without state feedback of the free link, using the nonlinear characteristics of the bifurcations produced in the free link under the high-frequency excitation of the active (first) link attached to the actuator. It is theoretically shown according to the bifurcation theory that the stable equilibrium states of the free link vary depending on the configuration of the active link with respect to the direction of gravity. Then, the set of positions where the tip of the free link can reach and be stable, i.e., the reachable and stabilizable area, is theoretically clarified under the combination of the excitation frequency and the configuration of the active link. Furthermore, experimental results show the validity of the theoretically predicted reachable and stabilizable area.     

Optimal control overhead based multi-metric routing for MANET

Wireless Networks - During the last two decades, there has been a tremendous growth in the use of MANETs, not only due to the development of the technology but also due to their high flexibility....     

基于模拟载荷的起重机械电气控制系统仿真研究

通过对研制基于模拟载荷的起重机械电气控制仿真系统的意义论述,分析了起重机械电气控制仿真系统的研究现状,提出了起重机械电气控制系统仿真的技术方案,并对其功能、结构和原理作了说明。     

塔吊远程上锁及控制系统研究开发

为了提高塔吊在施工过程中的安全性和满足设备租赁的需求,文中设计了一套能够对塔吊进行远程上锁及控制的系统.本系统由运行在PC机上的上位机通过网络发送指令,远端的89C52单片机通过GPRS模块接收识别PC机指令,然后,89C52单片机通过继电器模块实现对塔吊的远程上锁和控制;使用VB编写上位机软件,包括用户认证、塔吊控制界面等功能模块,保证操作的安全性.通过实验证明了该控制系统的有效性.     

基于嵌入式的智能塔吊远程控制系统的设计

为提高塔吊操作的可靠性与安全性,解决操作人员高空作业问题,实现塔吊的远程智能化控制,借助于嵌入式技术,研究设计一个基于嵌入式的智能塔吊远程控制系统。系统分为处理器和无线控制器两部分,通过无线控制器中的PC机向塔吊操作人员显示塔机实时运行情况及工作参数等信息,同时位于塔吊上的处理器接收控制器发出的动作指令,通过驱动接口电路控制塔吊的运行。塔吊操作人员远离现场,施工作业的安全性和自动化都得到了极大地提高,减少安全事故发生。     

An approach to control laws for arm motion

This paper is concerned with the investigation of arm motion between fixed boundary conditions within a two-dimensional space. An approach to the mathematical modeling and formulation ofthe control laws which govern arm reaching motion is presented.     

Electromagnetic induction and surface impedance in a half-spacefrom an overhead moving current system

How does an overhead current system having a velocity v influence the electromagnetic (EM) fields and the surface impedance as measured on the ground? We attempt to answer this question in this paper. A formulation is given for the fields produced by a current system having a uniform translational velocity. The numerical results that reflect the influence of velocity on the surface impedance at the air/earth boundary are presented. The relativity effect is not considered     

Displacement control of a mobile crane using a digital hydraulic power management system

The Digital Hydraulic Power Management System (DHPMS) is an innovation that is claimed to significantly improve the energy efficiency of hydraulic systems. It is based on digital pump-motor technology but has multiple independent outlets; hence, the transformer function can be realized as well. A new idea is to connect the outlets of the DHPMS directly into the cylinder chambers without any throttling valves in order to minimize hydraulic losses and to enable energy recovery. This article introduces the first experimental results of using this direct connection approach. Firstly, the system under study is presented and then a method for the displacement control is proposed. Open-loop position tracking responses with different loadings are presented, as is an analysis of the accuracy of steady-state velocity tracking. In addition, energy losses in the system are studied. The results show that the technique is valid. Moreover, the open-loop positioning error is under one percent in the measured trajectories, even though the DHPMS used has only six pistons. However, more pistons will be needed to improve the control of low velocities and to reduce the pressure ripple. On/off valve technology is a challenge, and compact, fast and leak-free valves with high flow capacity are required.     

Theory of control mechanism for an opticallytime-division-multiplexed system

The problem of phase control in a synchronous bit interleaved optical transmission system network is addressed theoretically and a practical implementation demonstrated. Control information is derived from the amplitude and phase of a discrete frequency component of the interleaved data spectrum, and it is shown that control is possible with a system penalty of less than 0.2 dB     

Automated control synthesis for an assembly line using discrete event system control theory

The design of logic controllers for event-driven systems continue to rely largely on intuitive methods rather than on formal techniques. This approach results in a control code that requires extensive verification, is hard to maintain and modify, and may even fail at times. Supervisory control theory (SCT) provides a formal approach to logic control synthesis. In order to demonstrate the usefulness of the supervisory control theory in manufacturing systems, an educational test-bed that simulates an automated car assembly line has been built using LEGO/spl reg/ blocks. Finite state machines (FSMs) are used for modeling operations of the assembly line, and for the specifications that accomplish the task of successfully completing the assembly repeatedly. Using the technique of SCT, we derive a supervisor that enforces the specifications while offering the maximum flexibility of assembly. Subsequently a controller is extracted from the maximally permissive supervisor for the purpose of implementing the control by selecting, when possible, at most one controllable event from among the ones allowed by the supervisor. Testing to check the correctness of the control code is reduced, since the controller is guaranteed to enforce the specifications.     

Nonlinear internal-model control for switched reluctance drives

A nonlinear internal-model control (IMC) based on suitable commutation strategy for switched reluctance motors (SRMs) is proposed. In the commutation strategy, a fixed critical rotor position is defined as the commutation point, which results in reduced computation. Combined the simplicity of the feedback linearization control and the robustness of IMC structure, the proposed drive has excellent dynamic and static performances for the torque and current control. The scheme is analyzed, and some important properties are obtained. Simulations and experiments were carried out on a 7.5 kW four-phase SRM, and the results show that the ripple of the output torque is very low in spite of model-plant mismatches     

一种宽范围自动曝光控制系统的设计

为了获得高清晰的地面目标图像,航空摄影机需要自动控制曝光。提出了一种光圈和快门曝光时间都可以变化的宽范围自动曝光控制原理,给出了宽范围自动曝光控制系统的硬件原理电路和软件设计,经测试和使用证明,此系统适应曝光范围大,控制精度高,工作稳定可靠。     

A sensorless optimal control system for an automotive electric power assist steering system

This paper considers the analysis and design of a double-pinion-type electric power assist steering (EPAS) control system. A simplified model of the augmented steering assembly-electric motor system is developed using Lagrangian dynamics, and an optimal controller structure for the model is proposed. Three main advances to the state of the art are presented in this paper. First, a state-space design model is used rather than an input-output model. A state-space formulation for a system model that incorporates motor electrical dynamics is obtained with the assist motor angular position as the output. Second, linear quadratic regulator (LQR) and Kalman filter techniques are employed to arrive at an optimal controller for the EPAS system. The selection of weighting coefficients for the LQR cost function is discussed. Finally, the authors present a control strategy that eliminates the steering column torque sensor, a critical component in existing EPAS controller designs. The proposed control strategy presents an opportunity to improve EPAS system performance and also reduce system cost and complexity.     

车载雷达机电控制系统安全性设计

车载雷达机电控制系统具有执行机构多、驱动电机多、传感器多和控制系统复杂的特点,因此对其进行安全性设计是十分必要的。机电控制系统安全、可靠地工作也是整部雷达正常工作的前提。本文以某型岸基车载雷达为例,系统地介绍了该型车载雷达机电控制系统在安全性方面所进行的设计。     

Minimum stopping distance for linear control of an automaticcar-following system

Linearized longitudinal dynamics of an automatic car-following system are analyzed to determine the minimum headway required to avoid collisions. We determine the linear controller with multiple control factors that satisfy all of the system constraints and have a minimum stopping distance. The constraints are stability, no oscillations, and the control forces remaining within a specified physical limitation of the vehicle. Numerical results show that a linear controller that satisfies all of the system constraints requires a large headway in order to avoid collisions when subject to extreme initial conditions. The results indicate the need for a nonlinear controller if collisions are to be avoided with proposed small headways     

Multinational data-privacy laws: an introduction for IT managers

Information-technology managers at United States companies are likely to be affected by recent legislation in the European Union and in Canada that restricts the transfer of citizens' personal information to countries that do not protect that information adequately. We argue that, from both ethical and pragmatic perspectives, USA businesses should reject the voluntary, self-certifying approach to data protection currently in favor in the United States. USA businesses should advocate instead for a European approach that mandates stronger data protection and establishes a government agency charged with enforcing it. If the USA adopted a European approach to data privacy, USA businesses would attract more customers and avoid the legal problems that are likely to result when European and Canadian data-privacy authorities begin to enforce their new laws vigorously.