Web guide process in cold rolling mill :Modeling and PID controller

There are many intermediate web guides in cold rolling mills process such as CRM (cold rolling mill), CGL (continuous galvanizing line), EGL (electrical galvanizing line) and so on. The main functions of the web guides are to adjust the center line of the web (strip) to the center line of the steel process. So they are called CPC (center position control). Rapid process speed cause large deviation between the center position of the strip and the process line. Too much deviation is not desirable. So the difference between the center position of the strip and the process line should be compensated. In general, the center position control of the web is obtained by the hydraulic driver and electrical controller. In this paper, we propose modelling and several controller designs for web-guide systems. We model the web and guide by using geometrical relations of the guide ignored the mass and stiffness of the web. To control the systems, we propose PID controllers with their gains tuned by the Ziegler-Nichols method, the H∞ controller model-matching method, and the coefficient diagram method (CDM). CDM is modified for high order systems. The results are verified by computer simulations.     

Function block applications in control systems based on IEC 61804

A variety of fieldbus technologies and digital fieldbus devices have been introduced within the process industries over the last ten years. There has been a gradual acceptance of the fact that a variety of communication technologies are needed to fully address the application requirements of a manufacturing facility. However, engineers responsible for the specification, engineering, and implementation of control systems require that a common interface and functionality be provided in the control system. This capability should be independent of the underlying fieldbus technology or manufacturer of the fieldbus device. The draft IEC 61804 standard defines how a control system can be structured to provide this flexibility in the utilization of fieldbus technology. In this paper, we discuss how a consistent function block capability may be provided for all fieldbus technology utilized in a control system. Examples will be given of how this standard has been applied in modern control systems to give a consistent interface to Foundation Fieldbus and PROFIBUS. Some detail will be presented on the standard means that is defined for manufacturers to describe function block capability of a field device. An analysis is given of the impact and benefit that the IEC 61804 standard will have on the process industry and on manufacturers of control systems.     

液压系统污染物的产生及其控制

对液压系统而言,保持油液介质的清洁度是十分重要的。详细地分析了油液污染物的产生和对系统的影响,以及对油液介质污染的有效控制措施。液压系统的污染控制过程实质上是污染物侵入和过滤的动态平衡过程,应及时掌握油液的污染情况,并根据结果采取相应的措施。     

In search of the Cheshire cat: the invisible automation system paradox Presented at the World Batch Forum

In a paper at the first World Batch Forum, entitled The Amazing Invisible Batch Automation System, we put forth the premise that process control systems should be transparent to their users. That is, the control system should create the illusion that the user is interacting directly with the process, rather than with the control system itself. At the same time, the system's job is to act as the brains of an otherwise dumb process, thus making that process appear to be “intelligent”. This paper discusses the architectural implications of the “invisible system” concept in more detail. In particular, we introduce the seemingly paradoxical concept that the desired invisibility of the automation system is best achieved by implementing an explicit model of the system itself, as well as one of the process under control. We focus particularly on the effective use of object models and on crucial decisions regarding the proper partitioning of responsibility in the system.     

Classification of leak locating systems

In the technological process of welding engineering and in high-tech fields such as the aircraft, space, radio electronics, and nuclear industries, highly efficient systems for tightness control capable of detecting leakage (localization of leaks) in welded joints are required. These systems should meet high requirements for precision and efficiency of testing. The existing leak detecting tools do not completely satisfy these requirements; therefore, presently it is important to design efficient systems for leak localization.     

A membrane method of protection of concentration field of leakage of a probe gas

In the technological process of welding engineering and in high-tech fields such as the aircraft, space, radio electronics, and nuclear industries, highly efficient systems for tightness control capable of detecting leakage (localization of leaks) in welded joints are required. These systems should meet high requirements for precision and efficiency of testing. The existing leak detecting tools do not completely satisfy these requirements; therefore, presently it is important to design efficient systems for leak localization.     

自动化装配设备的总体设计

根据自动化装配设备的特点,提出在自动化非标装配设备设计中,从装配工艺、功能分析、结构布局、机构系统和控制系统等方面进行总体设计,优化和合理的总体设计可以加快非标装配设备的设计进度,保证自动化装配设备系统的可靠性.     

Research and Development Trend of Shape Control for Cold Rolling Strip

Shape is an important quality index of cold rolling strip. Up to now, many problems in the shape control domain have not been solved satisfactorily, and a review on the research progress in the shape control domain can help to seek new breakthrough directions. In the past 10 years,researches and applications of shape control models, shape control means, shape detection technology, and shape control system have achieved significant progress. In the aspect of shape control models, the researches in the past improve the accuracy, speed and robustness of the models. The intelligentization of shape control models should be strengthened in the future. In the aspect of the shape control means, the researches in the past focus on the roll optimization, mill type selection, process optimization, local strip shape control, edge drop control, and so on. In the future, more attention should be paid to the coordination control of both strip shape and other quality indexes, and the refinement of control objective should be strengthened. In the aspects of shape detection technology and shape control system, some new types of shape detection meters and shape control systems are developed and have successfully industrial applications. In the future, the standardization of shape detection technology and shape control system should be promoted to solve the problem of compatibility. In general,the four expected development trends of shape control for cold rolling strip in the future are intelligentization, coordination, refinement, and standardization. The proposed research provides new breakthrough directions for improving shape quality.     

The fifth generation process control architecture

The “fifth generation” architecture for process control systems will be based on the use of a “field bus” as being defined by the ISA SP50 standards committee. While a name has not yet been given to this architecture, this paper will call it “Network Control” to distinguish it from the fourth generation “Distributed Control”. While all previous generations worked to increase the operator's span of control, this new architecture will achieve most of its benefits through increased functionality and performance and decreased installed cost. One major driving force for this architecture should be the rapid segmentation of the process control market where parts of a total system would be supplied by the vendors most able to meet the user's needs at the lowest price. The effect of this will be a restructuring of the process control market, to the benefit of those users who can take advantage of the changed product offerings. While it is expected that all of the traditional process control system vendors will participate with their total product lines, they will no longer be able to control the market. The new functionality may also be the final blow to second generation pneumatic and electronic analog control systems.     

Concepts for validating intelligent process measurements

With increased automation, operational validation is vital for effective control, maintenance and management of industrial plants and processes. Validation should be traceable, starting from the interface to the process up to the highest level of operations. At present, validation is focused at the systems level and current methods are based on condition monitoring, and fault detection and isolation techniques using functional, analytical and hardware redundancy. With the focus at the systems level, redundancy methods exploit integration and fusion of information from multiple measurement devices, and thus tend to disregard validation of the operation of the individual devices themselves. Transducers and sensors provide an interface to the process and produce measurement information. Validation of the measurement output from a sensor is imperative in situations where the cost of redundancy may be prohibitive. This paper presents concepts for validating measurements made with intelligent devices. The proposition is that an intelligent device should provide both measurement and condition information. The condition information should be used to assess the validity of the measurement by identifying metrics which describe the sensor and process conditions, respectively. This is the lowest level of validation because it occurs at the interface with the process being monitored. The information required for this level of validation can be obtained by utilizing all the components of the signal produced by a sensor, providing that the sensor has a wide frequency response. An example of a validation approach which follows from this argument is briefly described.     

Effectiveness of flexible routing control

Flexibility in part process representation and in highly adaptive routing algorithms are two major sources for improvement in the control of flexible manufacturing systems (FMSs). This article reports the investigation of the impact of these two kinds of flexibilities on the performance of the system. We argue that, when feasible, the choices of operations and sequencing of the part process plans should be deferred until detailed knowledge about the real-time factory state is available.To test our ideas, a flexible routing control simulation system (FRCS) was constructed and a programming language for modeling FMS part process plans, control strategies, and environments of the FMS was designed and implemented. In addition, a scheme for implementing flexible process routing called data flow dispatching rule (DFDR) was derived.The simulation results indicate that flexible processing can reduce mean flow time while increasing system throughput and machine utilization. We observed that this form of flexibility makes automatic load balancing of the machines possible. On the other hand, it also makes the control and scheduling process more complicated and calls for new control algorithms.     

A study on multivariable process control using message passing across embedded controllers

Multivariable process control forms an important part of modern day control. While hardwired controllers still constitute the basic component of such control systems, with reducing communication latencies, controllers on the network are being mooted as a viable alternative. These controllers promise a large number of advantages in terms of reduction in wiring and greater flexibility in implementing supervisory control systems. In this paper, a study is presented which shows that UDP (User Datagram Protocol) can actually be used for real-time multivariable process control. Latency reduction algorithms used in high performance message passing systems have been used.     

微流体控制系统研究及其应用前景

微流体控制系统是随着微机电系统的发展而迅速发展起来的研究领域。详细介绍了微流体控制系统的组成及其各元件的种类、研究发展历程,描述了系统的应用前景以及国内外在该领域的研究状况,提出了重视该领域的研究与应用已迫在眉睫。     

Fundamental study and theoretical analysis in a constrained-surface stereolithography system

Stereolithography (SL) technology can be classified into two types, free-surface and the constrain-surface SL systems. Constrain-surface stereolithography (SL) systems have the advantages of resin savings, reduced cost and better layer thickness control. However, the material properties of the curing process and the fabrication parameters need to be determined and optimal process parameters should be found using numerical analysis in order to eliminate trial and error. This paper reports some fundamental experiments that have been conducted in order to explore the curing properties of the resin NAF202 in an E-DARTS system. In addition, a theoretical analysis of the photopolymer curing process in the E-DARTS system has been proposed. A dynamic finite element simulation code with weight function was developed to model the point-by-point curing process in a constraine-surface SL system. A simple implementation to evaluate the developed program is presented, indicating that the proposed program can simulate the shrinkage analysis in accordance with path planning.     

基于TwinCAT平台的多轴开放体系结构设计与实现

针对现行多轴数控系统体系结构存在的开放程度不高等问题,提出了一种关于多轴开放体系结构设计新思路：开放的硬件系统应该建立在一种标准的、通用的硬件基础之上;开放的软件系统则应该建立在模块化结构的软件基础之上。基于上述思路,分析了TwinCAT工控软件的特点、功能以及其在开发数控系统时具有的优越性,对基于TwinCAT工控平台的开放式多轴系统软硬件结构设计和实现过程进行了相应阐述。通过伺服系统与控制卡间的硬件连接,结合VC＋＋程序设计,实现了一个基本的开放体系结构模型,为后续多轴数控系统的深入开发积累实际经验。     

大滞后控制系统性能的小波变换分析方法研究

过程控制系统以大滞后环节为特征，通常使用PID控制器来稳定系统性能。PID控制系统结构简单，倘若参数整定合适，系统将具有较强的鲁棒性。但是，在实际系统中，由于大滞后环节的存在，当参数调节不合适时，将会导致系统持续振荡。对于过程系统数据，应用小波变换后，可以确定精确的时滞时间，从而进行PID参数整定，更好地发送系统性能。     

Process computer audits

Even though a process computer system is designed with the best technology, the safety of the system can be compromised in its installation, operation, and management. For this reason, process computer audits should be performed. This paper concentrates on the items a process computer auditor should inspect when performing an audit. The areas included in the audit are fire protection, the environment, electrical power, ergonomics, fail-safety, alarms, safety interlock systems, security, design change control, contingency plans, maintenance, training, operations, and documentation.     

基于电液伺服控制实现的连铸机结晶器振动装置

针对采用电动机驱动偏心凸轮传统结晶器振动装置存在的缺点,开发研制了基于电液伺服系统实现的结晶器振动装置及其计算机控制系统。为了满足连铸工艺对跟踪非正弦给定振动波形的要求,基于智能控制的基本思想对一些控制方法进行了改进,有效地抑制了非对称负载造成的静差并提高了系统的相频宽。联机试验表明,所研制的结晶器电液伺服振动装置及其计算机控制系统能够根据连铸工艺要求实时、准确、方便地改变振动波形,从而有效地提高了连铸自动化水平。     

集散控制系统的最新技术特点与展望

集散控制系统(DCS)因其具有控制和危险分散、管理和显示集中的显著特点仍被作为当今工业过程控制领域的主要控制系统之一.该文在对DCS的基本体系结构和技术特点进行必要阐述的基础上,描述了DCS的发展现状,介绍了最新DCS的技术特点,列举了和FCS比较DCS存在的问题,最后对DCS的发展作出了包括和FCS结合,打造更加完善的综合系统;出现更多满足中小用户需求的中小型DCS;具有无线通信功能;智能控制、智能诊断等四方面的展望.     

Proceeding of human exoskeleton technology and discussions on future research

After more than half a century of intense efforts, the development of exoskeleton has seen major advances, and several remarkable achievements have been made. Reviews of developing history of exoskeleton are presented, both in active and passive categories. Major models are introduced, and typical technologies are commented on. Difficulties in control algorithm, driver system, power source, and man-machine interface are discussed. Current researching routes and major developing methods are mapped and critically analyzed, and in the process, some key problems are revealed. First, the exoskeleton is totally different from biped robot, and relative studies based on the robot technologies are considerably incorrect. Second, biomechanical studies are only used to track the motion of the human body, the interaction between human and machines are seldom studied. Third, the traditional developing ways which focused on servo-controlling have inborn deficiency from making portable systems. Research attention should be shifted to the human side of the coupling system, and the human ability to learn and adapt should play a more significant role in the control algorithms Having summarized the major difficulties, possible future works are discussed. It is argued that, since a distinct boundary cannot be drawn in such strong-coupling human-exoskeleton system, the more complex the control system gets, the more difficult it is for the user to learn to use. It is suggested that the exoskeleton should be treated as a simple wearable tool, and downgrading its automatic level may be a change toward a brighter research outlook. This effort at simplification is definitely not easy, as it necessitates theoretical supports from fields such as biomechanics, ergonomics, and bionics.