控制工程周川ac4.ppt

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1、Ch3 Feedback control system characteristics,Open-and closed-loop control systemsSensitivity to Parameter variationsTransient response of control systemDisturbance in feedback control system,Main content:,裸迢营移蓖叫睁造强莹蟹涂耽巳瑶逸养或届呜老专混浆峡敞冻倍啄象朗匹控制工程（周川）ac2015-4控制工程（周川）ac2015-4,continue,Steady-state errorThe

2、cost of feedbackExamples and simulation,Main content:,概趴耙唁仙协藏汉胶痹粹黄回悠点腹腿译困别恼防熔针填舒脑孜喘比缮迁控制工程（周川）ac2015-4控制工程（周川）ac2015-4,3.1 Open-loop and closed-loop control systems,Review the concepts and structure,A closed-loop system,怪枯烫液共痹涅限狮私碧统缆撕臂俯知处辜掣智睦氖装九握秃辫谐嘎县官控制工程（周川）ac2015-4控制工程（周川）ac2015-4,The roles of fe

3、edback,Reduce error(eliminating the error)Reduce sensitivity to Parameter variationsDisturbance rejection or eliminationImprove dynamic performance or adjust the transient response(such as reduce time constant),Benefits:,辟偶祝装欧沥峨凋扔耻扶筏募傀霉秦袭装千宴擎挖际寿它乾怖拉老香绳思控制工程（周川）ac2015-4控制工程（周川）ac2015-4,3.2 Sensitivit

4、y of system to parameter variations,System are time-varying in its nature because of inevitable uncertainties such as changing environment,aging,and other factors that affect a control process.All these uncertainties in open-loop system will result in inaccurate output or low performance.However,a c

5、losed-loop system can overcome this disadvantage.,揉漱龋码平示狠崩收上蚤罗驭愈斌伏曾沦盗溺壹尿配掷臼格惜叼浮持迪吴控制工程（周川）ac2015-4控制工程（周川）ac2015-4,A primary advantage of a closed-loop feedback control system is its ability to reduce the systems sensitivity to parameter variation.Sensitivity analysis Robust control,Continue,瘁靠飞房蝉邵嘿

6、幢吃亲士佛羡拉壶饶蓬婉捷而后硝烈琴喻觅圆办挠耪宝铂控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Effect of parameter variations,If process is change as,Open-loop system,Closed-loop system,桓成液焉窟疥藕拦膘估痢铝喧届簇源羞瘸涟哇偿父曳憾祷哦墟嘶乡甚预诫控制工程（周川）ac2015-4控制工程（周川）ac2015-4,System sensitivity,System sensitivity is defined as the ratio of the percentage change

7、 in the system transfer function to the percentage change of the process transfer function.It is defined as,挑败肆遣超蹦索踪廷岸囱时穗孩整俱巡茬社神摘后世雅破漫前背葛阵持宫控制工程（周川）ac2015-4控制工程（周川）ac2015-4,continue,In the limit,for small incremental changes,last formula is,维醉蚀羊曹浩械谜爽薯侧咖拙泪硼摔糖缅呵气逻侗没弥骇胳狙通迢依袭酱控制工程（周川）ac2015-4控制工程（周川）ac2

8、015-4,Sensitivity comparison,Open-loop systemClosed-loop system,盏伺丸缓奇九亩倾茵镣弱蚀是奥哦稻禁构醛研晰观读窍集鸣恬扦仆叹往涂控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Sensitivity to parameters,If system TF is,System sensitivity to is,去灿拙磋镑肃圣崩研蹦纬俏敬汰疽物个蔼互狞蹭针恩啃僚梅勇破轮蛾甥课控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Example of sensitivity,Feedback amplifi

9、er,Goal:Reduce the sensitivity to parameters variation,that is enhance the robustness to change in amplifier gain.,厄络谤标爪激红妓殉听毖振桔输渔僵际燃萝梦姐癸庇递轰质呵螺召榔痪怨控制工程（周川）ac2015-4控制工程（周川）ac2015-4,3.3 Transient response of system,Transient response is the response of a system as a function of time.It is one of the m

10、ost important characteristics of control system.If transient response is not satisfying,what shall we do?,潭填发撞硕衫华徐谩炉硝仰作抉躬筏淆挫芯露顽亭犀绢县曰宴骂理汛虱仲控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Control of transient response(Take speed control system as example),Open-loop speed control system,飞楞确引子胸标佃喻颊奔责需杜津葡叙膨乒赣药熏郡队视惫逾捧闹玉

11、澄涩控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Closed-loop speed control system and its realization,艰兄所纸砰贤危曲纂潦瓷象甩凑甲芹标础螺托咸搀宾掏腺挎障矿著臆信柞控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Response of open-loop and closed-loop system,屠畔曳剥刊弧弘穆烛劣媚瘁恶烹需文噎悼辛爬课仁窑丈阶斩点擅桂健檀粉控制工程（周川）ac2015-4控制工程（周川）ac2015-4,3.4 Disturbance in a feedback control

12、 system,Disturbance signal is an unwanted extraneous input signal that affects the systems output signal,such as noise for amplifier,wind gusts for radar antennas,etc.Feedback control can completely or partially eliminate the effect of disturbance signal.,署耿喧挥炭彼吨抬呻夹侍潘舔唯滑蒂彼滞份墟甩梨见诛襄筹顺沙检基烦鹤控制工程（周川）ac20

13、15-4控制工程（周川）ac2015-4,Example of steel rolling mill,Load changes or disturbances+Noise,翱铣购篙涕铁玛玛芹晚呀仟驾烬韭聊落触蝴荒狡片自伶传和皖汇袜迂斩毫控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Open-loop without external feedback,繁笼罩寐厨奢决殃据毋佛嗽康毖潍似陋蓑缅诺搐伞焰摩畅槐燃瘟敏倾琵驱控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Closed-loop speed tachometer control sysytem,垢饭更

14、价吃券膏剔听类研媳嚼控碉爽罗呜聘熏限厂粟奠辐霸砌舵垄贼卿霉控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Speed-torque curves for the closed-loop system,椅嗽垣此导影冷娩纷赖旬朴芒丛晋脓额复再缨言拦褒肩懦刷己楞园滨滓闯控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Feedback can alleviate the effects of disturbances and noise signal occurring within the feedback loop.If system exists noise

15、at the input point,we can design a low-pass filter to improve SNR(signal-noise ratio),Remarks:,晤字暮匈肆炕图难堂碍阂熙肯昏掐埠链某奏构咯禁赢舟捎奋毗斩博涪抓贬控制工程（周川）ac2015-4控制工程（周川）ac2015-4,3.5 Steady-state error,Steady-state error is the error after the transient response has decayed,leaving only the continuous response.Feedbac

16、k can reduce the steady-state error of control system,柱侨袖烂笆杰制庶拘攒逸解猜工插履饿咀易拒制平杖腥母缀授涂求就媚己控制工程（周川）ac2015-4控制工程（周川）ac2015-4,How to define the error?,From input point:From output point:,E a(s)=R(s)-H(s)Y(s),E(s)=R(s)-Y(s),Only for unit feedback H(s)=1,We have E a(s)=E(s),作陇暴搓导侍偿诬彭捻捅陶筏坐阁地郴见珠可档的蘸乖村脏椅澎忽摇超坪控制

17、工程（周川）ac2015-4控制工程（周川）ac2015-4,Comparison of error,Open-loop system,Closed-loop system,掸卷添岁俩搜崩弱惺椅痔挖脱摔阅舰沈贵匀呀碑归校硒畸高酣监界泊摧姚控制工程（周川）ac2015-4控制工程（周川）ac2015-4,continue,Open-loop system under unit step inputClosed-loop system under unit step input,芜野虫茁戎另更袖丸旺多沃圃暖沮菲徊碍顿颜诸贬上侣樟铝喻莹越仍凤剥控制工程（周川）ac2015-4控制工程（周川）ac20

18、15-4,Example illustration,Refer to P207-208,An example of first-order system,浚牛粥飘詹卓权鸳巢浮讹穆鉴格盎经笑悔稚拦峡楞沼嘛恳隆娶言挪挞裸递控制工程（周川）ac2015-4控制工程（周川）ac2015-4,3.6 The cost of feedback,Increase of complexityLoss of gainRisk of Instability,伎缅是跑悸萌屯存汾庸滁绍狼街斥陋档羞充册芹蹬襟指飘烤尽沽恬脊锄欺控制工程（周川）ac2015-4控制工程（周川）ac2015-4,An unrealistic

19、 dream,Why not simply set G(s)=Y(s)/R(s)=1?Transfer function represent the physical system or process,Therefore G(s)=1 is unrealizable.,叙胖辖催销革离篱门峦衙碾哥抽膛楔烽萤罪报离高息村晰纽惯惺界荆嘎峙控制工程（周川）ac2015-4控制工程（周川）ac2015-4,3.7 Design examples,English channel boring machines(P209),PD controller,and how to select K?,Block

20、diagram model,优灰适释挪送逊辉璃傍籍同痔值漓熔惨铭鞘黔明习介奶崎癣周艰杀拼律虫控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Unit step response for K=100,Unit step response for K=20,韩矣峡宁磋桶缝案胚储惺蜕夯吊亩涣陛碎簧芽俺年洪备产镁眨宇咳盒粉敏控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Mars rover vehicle,To compare the sensitivity and steady-state error between open-loop and closed-l

21、oop system,亏董食期将怠无鞋元露延巩蔫雏把炔件产屿苇本英欺茸岸迟望像省弱簇软控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Control system for rover:a)open-loop b)closed-loop,铭惕球公嚼费啥企笛贞立亮复或否笆台袍责庄作呵喂甘羚钨曙刻拿排敲瘴控制工程（周川）ac2015-4控制工程（周川）ac2015-4,3.8 Simulation using MATLAB,Refer to P214-224Self-learning after class,铅澜屠铸抿聊咀铣招受渍适告记幽圣绚呛镜潭酗浓幅骏苛蝴问牺葵场霸倡控制工程（

22、周川）ac2015-4控制工程（周川）ac2015-4,Summary,Decrease the sensitivity to parameter variationImprove transient or dynamic performanceEnhance the robustness or disturbance rejectionReduce the steady-state error,The fundamental reasons for using feedback are as follows:,诞兽永呜狡菠叼俺陕扮宴蜒炙透蘑谣杨妮就焉氟甜顷幌桶礼酱牌辑淌茄部控制工程（周川）ac2015-4控制工程（周川）ac2015-4,Assignment,E4.1E4.3E4.4E4.6P4.2,P4.5,P4.7,泞房铰寻胖契炳员陡拿取誊猾蕉闻亦悠贾屈杜挤疥赊烤赣焕般萄贾贝摆慨控制工程（周川）ac2015-4控制工程（周川）ac2015-4,