Smart manufacturing systems for Industry 4.0: Conceptual framework,scenarios, and future perspectives

Information and communication technology is undergoing rapid development, and many disruptive technologies, such as cloud computing, Internet of Things, big data, and artificial intelligence, have emerged. These technologies are permeating the manufacturing industry and enable the fusion of physical and virtual worlds through cyber-physical systems (CPS), which mark the advent of the fourth stage of industrial production (i.e., Industry 4.0). The widespread application of CPS in manufacturing environments renders manufacturing systems increasingly smart. To advance research on the implementation of Industry 4.0, this study examines smart manufacturing systems for Industry 4.0. First, a conceptual framework of smart manufacturing systems for Industry 4.0 is presented. Second, demonstrative scenarios that pertain to smart design, smart machining, smart control, smart monitoring, and smart scheduling, are presented. Key technologies and their possible applications to Industry 4.0 smart manufacturing systems are reviewed based on these demonstrative scenarios. Finally, challenges and future perspectives are identified and discussed.     

Development of Digital Machine-Building Production in the Industry 4.0 Concept

This article is devoted to the problems of development and implementation of digital production technologies at industrial enterprises. The structure of the technological processes and principal approaches to automation of production enterprises with various technological processes is considered. An analysis of the conditions of the change in the enterprises to multiproduct small-scale manufacturing is carried out. The problems of changing modern production enterprises to the Industry 4.0 concept are specified. The urgent problems are stated, solving of which is required to develop digital machine-building production in the Industry 4.0 concept. A definition of the digital production is proposed.     

电液元件数字化技术进展

本文简要介绍了电液数字阀的种类及结构特点。通过分析说明了电液元件数字化技术的优势，指出了电液元件向数字化方向发展是其必然趋势。     

煤矿铰接车辆线控转向技术综述

线控转向是提高煤矿铰接车辆在复杂环境灵活稳定运行的一项前沿基础技术,不仅能够提升铰接车辆转向性能,还是未来实现智慧矿山无轨辅助运输系统智能化、无人化的核心技术。针对铰接车辆线控转向技术,分析了线控转向系统的发展现状,阐述了线控转向系统应用于煤矿铰接车辆的优势,指出在应用过程中的痛点和难点;分别对线控转向系统的电液控制以及执行元件等在节能性和控制精确性等方面进行研究,归纳总结出适用于煤矿铰接车辆的电液泵控和电液阀控两大主流技术,分析对比了两种技术的原理和特点;聚焦铰接车辆线控转向的五大关键技术,提出了实现关键技术的路径;探讨了节能性、容错性、控制精度在未来的发展趋势。旨在通过对线控转向技术的研究,为煤矿铰接车辆转向性能的优化和实现自主行走提供科研思路,为更快地实现智能化无轨辅助运输打好扎实基础。     

液压及气动阀直接数字控制的新途径

介绍了一种由步进电机作为电一机械转换元件的数字阀实现电流（气）直接数字控制的新方法。该方法通过控制步进电机相邻相序通电时间的长短,实现阀的输出信号的连续可控。应用这种方法解决了传统的步进式电液（气）控制元件所存在的应速度与精度之间的矛盾,同时保持其固有的重复精度高、无滞环及线必了的优点。给出利用阀芯的双自由度原理设计的数字伺服阀在连续跟踪控制下的实验结果,表明采用新的数字控制方法可以使阀获得理想的     

Output waveform analysis of an electro-hydraulic vibrator controlled by the multiple valves

The existing research of the electro-hydraulic vibrator mainly focuses on system stability, working frequency width and output waveform distortion. However, this high frequency performance of the electro-hydraulic vibrator is difficult to be improved greatly due to fast insufficiently frequency response of the servo valve itself and limited compensation capability of the control structure in the vibrator system. In this paper, to realize high frequency vibration, an improved two-dimensional valve （here within defined as a 2D valve） as a main control component is adopted to the parallel connection with a servo valve to control the electro-hydraulic vibrator, Because the output waveforms of this electro-hydraulic vibrator are incapable to be verified through timely feedback as in the conventional electro-hydraulic servo system, the analysis to the output waveform becomes crucial to the design and control of the electro-hydraulic vibrator. The mathematical models of hydraulic actuation mechanism and the orifice area of the parallel valves connection are established first. And then the vibration process is divided into two sections in terms of the direction of the flow, the analytical expression of the excited waveform is solved. Based on relationships exist between working states and the control parameters the analytical results, the vibration boundary positions and the are derived. Finally an experimental system was built to validate the theoretical analysis. It is verified that this electro-hydraulic vibration system could achieve high working frequency, up to 2 000 Hz. The excited waveform is similar to the sinnsoidal waveform. And the ascent and decent slopes of the waveforms are somewhat asymmetrical. This asymmetry is not only caused by the change of the direction of the elastic force but also dependent on the bias position of the vibration. Consequentky the distortion of effective working waveform is less tha~ 10%. This electro-hydraulic vibrator controlled by the multiple valves could not only greatly enhance the working frequency but also precisely control the vibration characteristic variables such as waveform shape.     

液压支架电液控制系统技术的发展与现状分析

分析了支架电液控制系统对煤矿生产的重要性,介绍国内外液压支架电液控制系统技术发展概况,电液控制系统的原理和关键技术。分析中国发展支架电液系统技术落后的原因,对国内液压支架电液控制系统发展提出建议。     

现代电液控制技术的应用与发展

本文在对国内外电液元件、电液控制系统、现代控制技术相关文献调研的基础上,指出了电液控制技术已经向数字化转变,其发展过程是与控制策略的最新发展密切相关的。各种新颖控制手段的不断发展和完善,为电液控制技术在各领域的不断推广使用奠定了基础。     

An energy-saving nonlinear position control strategy for electro-hydraulic servo systems

The electro-hydraulic servo system (EHSS) demonstrates numerous advantages in size and performance compared to other actuation methods. Oftentimes, its utilization in industrial and machinery settings is limited by its inferior efficiency. In this paper, a nonlinear backstepping control algorithm with an energy-saving approach is proposed for position control in the EHSS. To achieve improved efficiency, two control valves including a proportional directional valve (PDV) and a proportional relief valve (PRV) are used to achieve the control objectives. To design the control algorithm, the state space model equations of the system are transformed to their normal form and the control law through the PDV is designed using a backstepping approach for position tracking. Then, another nonlinear set of laws is derived to achieve energy-saving through the PRV input. This control design method, based on the normal form representation, imposes internal dynamics on the closed-loop system. The stability of the internal dynamics is analyzed in special cases of operation. Experimental results verify that both tracking and energy-saving objectives are satisfied for the closed-loop system.     

Special issue on future digital design and manufacturing: Embracing industry 4.0 and beyond

Industry 4.0 as referred to the fourth industrial revolution has endorsed in several national manufacturing initiatives or development plans such as in Germany,the UK,USA and China.A set of important pervasive and secondary technologies for future manufacturing activities have been identified such as additive manufacturing,sensor technology,big data analytics,Internet of things,robotics,smart manufacturing,cloud computing,and nanotechnology.These exponentially growing technologies are radically changing industrial processes,accelerating them and making them more flexible and smarter.The interplay among "Internet of Things,services,data and people" will transform the future of manufacturing.     

Modeling,simulation and experimental validation of flow rate of electro-hydraulic hitch control valve of agricultural tractor

Advances in non-linear control theory have made it possible to develop controllers for non-linear dynamic systems in their nature. The low-cost proportional control valves of the hydraulic control system are examples of such a system where there is no linearity due to the structure of the valves and the flaws in the spool. However, the non-linear analysis and regulation of these hydraulic systems cannot be done without a proper valve model. This paper presents a methodology for the development of an efficient unified model of a three-point hitch (TPH) electro-hydraulic proportional control valve control system for agricultural tractors by means of a parameter estimation technique. Modeling and simulation of the proportional control valve was performed using MATLAB Simulink software. Parameter estimation methodology was used to optimize the effective orifice opening of the solenoid valve to meet the flow characteristics available in the manufacturer's technical data sheet for the proportional control valve model parameters. Such unified Simulink models are useful for simulation, practical capability testing, and non-linear control design. Modeling and simulation of electro-hydraulic hitch (EHH) control valve were made and simulation results were compared with actual experimental results. The simulation results of the TPH lifting and lowering time were found to vary 4 and 12.5 %, respectively with the experimental results. This type of parameterized valve models facilitates their implementation in dynamic simulation models of complex hydraulic systems.     

基于单片机的电液调速器控制系统设计

介绍了一种以AT89C52单片机为控制核心,结合由高速开关阀作为电液转换元件的电液执行器来实现的柴油机电液调速控制系统,给出了系统的硬件和软件设计方案,为柴油机机械式调速器进行改造提供了一种方案。     

300MN模锻水压机操纵系统改造方案研究

300MN模锻水压机原有操纵系统操作不便,控制精度低,响应速度慢,可靠性低。针对其机械本体特征及运行要求,改操作系统控制方式“水控水”为“油控水”方式,改操纵系统为数字电液伺服控制系统。新增加一油压系统,由操作手柄、按钮发出控制信号,通过PLC控制油压系统驱动执行油缸,实现分配器阀的正确动作;检测凸轮驱动机构的实际位置,反馈给控制系统,实现闭环控制,以实现对水压机的工作过程快速、精确、可靠控制。     

基于LabVIEW的电液伺服系统的设计与实现

设计了基于LabVIEW的电液伺服测控系统。系统通过传感器,数据采集卡,以及LabVIEW的PID工具包,对采集的数据进行实时分析和处理,最后达到对伺服油缸位置的控制。系统具有人机交互性强,控制精度高,稳定性好,使用方便等优点。     

伺服阀静态特性测试与状态模式识别智能系统研究

分析电液伺服阈静态特性与状态模式之间的映射关系，介绍基于BP神经网络的模式识别方法，以此为基础开发了具有伺服阀静态特性测试与状态模式识别功能的智能试验系统，并进行了实验研究。     

新型PZT元件驱动的电液高速开关阀及其大功率快速驱动技术的研究

针对目前电液高速开关阀脉宽调制频率较低的问题,研制了新型压电元件驱动的电液高速开关阀,并研究了该阀的动态特性和静态特性。该阀属于两位三通型锥阀结构的数字阀,样机产品达到了下述性能指标：工作压力p1=10 Mpa,额定流量qV,n=8 L/min,开启时间ton≈1.2 ms,关闭时间toff≈1.7 ms。还分析了这种阀的驱动电路及其工作原理,利用电路的暂态分析理论研究了该阀的大功率快速驱动技术。     

基于DSP和FPGA的运动控制器设计

根据全自动校直机多轴运动控制的要求,设计了一种基于DSP和FPGA技术的校直机专用多轴运动控制器。该控制器主要以数字信号处理器(DSP)为核心,通过FPGA进行功能扩展,实现了对多个交流伺服电机或电液伺服阀的全闭环控制。控制器集成了编码器信号采集、PLC接口、16位高速AD采集和计算机通讯接口,集成度高、运算速度快。     

DESIGN AND ANALYSIS OF NOVEL ACTIVE ACTUATOR TO CONTROL LOW FREQUENCY VIBRATIONS OF SHAFT SYSTEM

Aiming at providing with high-load capability in active vibration control of large-scale rotor system, a new type of active actuator to simultaneously reduce the dangers of low frequency flexural and torsional vibrations is designed. The actuator employs electro-hydraulic system and can provide a high and circumferential load. To initialize new research, the characteristics of various kinds of active actuators to control rotor shaft vibration are briefly introduced. The purpose of this paper is to introduce the preliminary results via presenting the structure, functions and operating principles, in particular, the working process of the electro-hydraulic system of the new actuator which includes a set of high speed electromagnetic valves and a series of sloping cone-shaped openings, and presenting the transmission relationships among the control parameters from control signals into the valves to active load onto shaft. The course of the work is dynamic, and a series of spatial forces and moments are put on the shaft to get an external resultant force to reduce excitations that induce vibration of shafts. By checking states of vibration, the actuator can control the impulse width and the interval of injection time for applying different control force to a vibration shaft in two circumference directions through the regulating action of a set of combination directional control valves. The results from simulating analysis and experiment show evidence of that this design can satisfy the case of active process of decreasing of flexural and torsional vibrations.     

基于虚拟仪器技术的电液比例阀性能测试系统设计

根据电液比例阀性能测试规范,开发了用于电液比例阀性能测试的计算机辅助测试（CAT）系统。利用虚拟仪器技术,设计了CAT系统软件,实现了测试系统所要求的信号发生器、系统参数调整与控制、信号采集与处理、数据分析计算等功能。使用结果表明,测试系统运行稳定、结果可靠、人机界面友好,提高了比例阀特性测试精度和测试效率。     

核电站非安全级DCS网络和主机信息安全防护

随着工业4.0的浪潮滚滚而来,核电站控制系统已经普遍改造为SCADA、DCS等数字化控制系统。工业以太网、工业现场总线,以及大量标准互联网技术已经被应用于核电站控制系统。本文将聚焦于网络安全和主机安全,探讨核电站非安全级DCS的信息安全防护。DCS网络安全防护将主要涉及3个方面,包括区域划分、边界防护和网络入侵防护。DCS主机安全防护将主要涉及集中管理,用于给出一种核电站非安全级DCS的信息安全防护方案,着重通过网络安全防护措施和主机安全防护措施,有效提高核电站非安全级DCS的信息安全防护能力。