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1、基于模糊PID的凹印机套准同步控制研究万鹏飞，王莉（中南大学信息科学与工程学院，湖南长沙，410075）摘要：无轴传动技术在凹版印刷上得到的广泛的应用。本文以凹印机套准系统的多电机同步问题为研究对象，采用基于补偿原理的模糊PID的同步控制算法，并搭建了以西门子S7-300 PLC为控制器的主从式同步控制系统，来进行多电机同步控制的研究。仿真表明，这种方案鲁棒性、快速性优良、动态过程同步误差小，能够较好地满足被控对象对高精度同步控制的要求。关键字：无轴传动;模糊PID;同步控制;伺服电机;中图分类号：TP271+.4The Research of Gravure printers registr
2、ation synchronization Control Based On Fuzzy-PIDWAN Peng-fei ，WANG Li（School of Information Science and Engineering，Central SouthUniversity,Changsha, 410075）Abstract: The shaftless drive technology has been widely applied on gravure printing. In this paper ,the gravure printer registration systems m
3、ulti-motor synchronization problem is regarded as the research object.For the purpose of research of multi-motor synchronization control ,the algorithm of Fuzzy-PID synchronization based on compensation principle is adopted and the Master-slave synchronization system based on SIMENS S7-300 PLC was d
4、esigned. The simulation results indicate that the proposed method has stong noise immunity and robustness and the rapidity is good and dynamical synchronous error is low .So this control method can satisfy the demands of the controlled subject for the high precision applicatios.Keyword:shaftless dri
5、ve ;Fuzzy-PID ;Synchronization control ;Servo motor;1 引言由于近代电力电子技术、微电子、控制理论、计算机技术以及传感器技术的发展，均为交流传动控制提供了广阔的前景，为设计出高精度、快速响应的交流传动系统奠定了基础，同时也使多电机同步控制研究成为可能。传统的多电机同步控制策略有等状态方式、主从方式等1。无轴传动技术是多电机同步控制的一种应用。它是指印刷机中每个机组，甚至是每个滚筒或辊子的动力都是相互独立的，分别采用单独的伺服电机，按照运动控制器发出的程序指令进行驱动，从而保证各机组间同步运转的传动方式2。其设备主要由三部分组成：放卷部分、印刷
6、部分、和收卷部分，其中印刷部分包括若干个色组。如图1所示。图 1 凹印机生产线示意图2 自动套准系统的多电机同步问题对于高速的凹版印刷，大多数凹印机都采用自动套准控制系统，套准系统是凹印机的重要组成部分，其主要功能是对于印刷各色组的套印情况进行实时跟踪、检测和调节，套准控制装置主要由光电扫描器、横向套准调节机构和纵向套准调节机构等组成，对套印误差的跟踪、检测由光电扫描来完成3。印刷过程中，承印物张力变化范围小，套印精度就容易控制。反之，如果张力变化频繁，则会严重影响套准精度。所以，在设定合理张力后，还要保持最小范围的张力波动，即保持张力稳定，各电机间的位置和速度同步问题是影响张力一个重要因素。
7、因此在不考虑其它因素的前提下，研究自动套准系统关键就在于多电机的同步控制。目前，使用工业现场总线是解决多电机同步的最佳方案。常用的现场总线有SERCOS、PROFIBUS等4。在文中采用的西门子S7-300PLC具有强大的功能，可以完成各种先进的算法，通过算法实现对多电机的同步控制，不采用现场总线。3 同步设计方案对于套准控制系统来说，主要要解决解决的问题是整个连续运转下情况下，保证每个印刷套色单元在任何相同的时刻都是位置同步的，要实现这一功能对于无轴套色系统来说，就是通过“电子轴”完成各独立印刷单元的同步传动，同时还要分别控制各色偏差修正，进行位置微调5。本文所设计的自动套准系统为主从式结构
8、,采用直接速度差补偿的同步方法，文中仅以两轴为例。如图2所示，就是将主轴与从轴的反馈速度之差，经过补偿器计算出补偿量加到主从轴的速度给定上。因为主从轴的速度之差可以反映主从轴速度的差异，将此量经过补偿器以后分别加到主从轴的速度给定上，从而实现主从轴速度的准确同步。系统设计如下：采用西门子S7-300作为主控单元,通过RS485总线通讯跟两台西门子440变频器相连接。这两台变频器分别控制一台主电机和一台从电机，两台电机都带有编码器反馈转速，编码器反馈转速给变频器的同时也反馈给PLC,PLC根据反馈的转速做相应的处理。以两台电机为例,主电机根据指令启动通过安装在电机上的测速装置反馈电机的转速,此转
9、速反馈给PLC和驱动器1,在驱动器中进行主电机的PID运算,对主电机进行闭环控制。同时,从电机根据此转速启动,并反馈给转速给驱动器2和PLC,驱动器2进行从电机的PID运算控制电机的运转速度。但是随着工艺精度的要求,驱动器2中简单的PID运算显然达不到控制的精确性。为达到从电动机高速响应主电机的速度变化及迅速排除从电机中的扰动,在PLC中设计一个补偿器进行运算从而得到相应的补偿信号。首先在PLC中设计一个转速比较器将主从电机反馈的转速再进行比较后得出转速差。然后再设计一个模糊PID控制器,在其中进行运算后得出一个补偿值,从而实现整个多电动机同步运行控制。图 2主从式同步控制原理图4 模糊PID
10、控制算法文中应用模糊推理的方法实现PID参数的在线自调整，使系统动态过程各阶段的PID参数处于最佳状态，以获得满意的控制效果。参数自调整模糊控制的思想是找到PID控制器的三个参数与之间的模糊关系。在运行中通过不断检测模糊输入量和，再根据模糊控制规则对三个输出参数进行在线修改，以满足不同和对控制参数的不同要求，从而使被控对象具有良好的动静态性能6。按照这种思想构成的控制系统由两部分组成，即常规PID部分和模糊推理的参数校正部分如图3所示。图3 参数自调整模糊控制器框图在偏差论域和偏差变化论域上分别定义7个模糊子集NB,NM,NS,ZO,PS,PM,PB，且输出量的模糊子集也为NB,NM,NS,Z
11、O,PS,PM,PB。同时隶属度函数均采用对称三角函数，通过总结以往工程实际操作经验，针对不同的速度误差和速度误差变化率总结出的整定原则。根据三个参数的调整原则，并结合可得到的调节规则表。模糊推理与解模糊选用Mamdani法7。对于控制规则 IF AND THEN is （i=1,2,49）其模糊蕴含采用最小值法()= （）（）（）; 模糊合成采用最大法，即最终结论是由综合,得到的，推理法则为()= () () (); 在一次采样时刻，的值可由模糊输出的重心确定。= 式中 (j=1,2,49)是的隶属度。同理可以得到输出量，。 其中, , 是模糊推理的结果，即参数的校正量。而为参数设置初值。5
12、 实验仿真本文在空载情况下，采用两台参数相同的永磁同步电机进行仿真，具体参数如下：磁链=0.175wb,=805Mh,=8.5Mh, p=4,转动惯量为J=0.001;额定电磁转矩Tm=30Nm;图4为采用常规PID同步控制算法下系统响应曲线，图5为采用模糊PID同步控制算法下系统响应曲线。比较两种仿真结果可以看到，采用模糊PID方法时，系统的同步性能、抗干扰能力优于采用常规PID的性能。 图4 采用传统PID控制算法系统输出响应曲线图5 采用模糊PID控制算法系统输出响应曲线6结论本文以凹印机自动套准系统的多电机同步问题为研究对象，并搭建了主从式同步控制系统，采用基于模糊PID的同步控制算法
13、来对多电机同步系统进行研究。由实验仿真表明，与常规PID同步控制算法相比，采用模糊PID同步控制算法的系统同步性能更好，速度响应能力和鲁棒性能也都得到了显著的提高，能够较好地满足被控对象高精度的要求。参考文献1张海燕,王伟.无轴传动控制策略及仿真分析.自动化技术与应用J,2007,5(2)：3738.2吕砺.独立驱动技术的发展及其在凹版印刷上的应用前景.印刷杂志J，2002,47(5):67-70.3彭建华.浅谈影响凹印套色的常见因素及注意事项.今日印刷J，2004,26（9）:4546.4唐苏亚.无轴传动技术在凹版印刷机中的应用.微电机J，2006,5（39）：6972.5陈德传，卢玲.组合
14、式凹版印刷机彩色套准控制系统.控制系统J，1999，6（3）:4245.6刘铁湘，陈林康.模糊控制在伺服系统中的应用及其仿真.电机电器技术J，2003，2（9）：3840.7崔巍，张文休.一种基于PLC的模糊控制方法.机电一体化J，2001，3（6）：2224.作者简介：万鹏飞，男，（1983-），江西南昌人，中南大学硕士研究生，研究方向：智能控制和运动控制投稿日期：2008-09-11作者登记信息:作者姓名(全部): 万鹏飞，王莉作者单位: 中南大学信息科学与工程学院王莉：中南大学信息科学与工程学院副教授，研究方向：智能控制和运动控制稿件名称：基于模糊PID控制的凹印机套准系统同步控制研究联
15、系地址：湖南省长沙市中南大学铁道学院电子楼403室邮编：410075手机：13467664177邮箱：sourfox2008Editors note: Judson Jones is a meteorologist, journalist and photographer. He has freelanced with CNN for four years, covering severe weather from tornadoes to typhoons. Follow him on Twitter: jnjonesjr (CNN) - I will always wonder what
16、it was like to huddle around a shortwave radio and through the crackling static from space hear the faint beeps of the worlds first satellite - Sputnik. I also missed watching Neil Armstrong step foot on the moon and the first space shuttle take off for the stars. Those events were way before my tim
17、e.As a kid, I was fascinated with what goes on in the sky, and when NASA pulled the plug on the shuttle program I was heartbroken. Yet the privatized space race has renewed my childhood dreams to reach for the stars.As a meteorologist, Ive still seen many important weather and space events, but righ
18、t now, if you were sitting next to me, youd hear my foot tapping rapidly under my desk. Im anxious for the next one: a space capsule hanging from a crane in the New Mexico desert.Its like the set for a George Lucas movie floating to the edge of space.You and I will have the chance to watch a man tak
19、e a leap into an unimaginable free fall from the edge of space - live.The (lack of) air up there Watch man jump from 96,000 feet Tuesday, I sat at work glued to the live stream of the Red Bull Stratos Mission. I watched the balloons positioned at different altitudes in the sky to test the winds, kno
20、wing that if they would just line up in a vertical straight line we would be go for launch.I feel this mission was created for me because I am also a journalist and a photographer, but above all I live for taking a leap of faith - the feeling of pushing the envelope into uncharted territory.The guy
21、who is going to do this, Felix Baumgartner, must have that same feeling, at a level I will never reach. However, it did not stop me from feeling his pain when a gust of swirling wind kicked up and twisted the partially filled balloon that would take him to the upper end of our atmosphere. As soon as
22、 the 40-acre balloon, with skin no thicker than a dry cleaning bag, scraped the ground I knew it was over.How claustrophobia almost grounded supersonic skydiverWith each twist, you could see the wrinkles of disappointment on the face of the current record holder and capcom (capsule communications),
23、Col. Joe Kittinger. He hung his head low in mission control as he told Baumgartner the disappointing news: Mission aborted.The supersonic descent could happen as early as Sunday.The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less
24、than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), driftin
25、g even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause), he can expect a lot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet (22.7 miles/36.53 kil
26、ometers). Here, Fearless Felix will unclip. He will roll back the door.Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.Below, the Earth becomes the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, hell be traveli
27、ng fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end.Skydiver preps for the big jumpWhen he jumps, he is expected to reach the speed of sound - 690 mph (1,110 kph) - in less than 40 seconds. Like hitting the top o
28、f the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him completely.If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes its not needed. Instead, he p
29、lans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).In order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach sp
30、eeds.Even if everything goes as planned, it wont. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters).It might not be the moon, but Kittinger free fell from 102,800 feet in 1960 - at the dawn of an infamous space race that captured the hearts of many. Baumgartner will attempt to break that record, a feat that boggles the mind. This is one of those monumental moments I will always remember, because there is no way Id miss this.
