自適應控制基本概念

　　1 什么是自適應控制

　　自(zi)(zi)適應(ying)控制：英(ying)文名稱(cheng)為adaptive control。在日常生活(huo)中，所謂自(zi)(zi)適應(ying)是指生物能改變自(zi)(zi)己的(de)習性以適應(ying)新的(de)環境的(de)一種特征(zheng)。因此，直觀地講，自(zi)(zi)適應(ying)控制可以看(kan)作是一個能根(gen)據環境變化(hua)智能調(diao)節自(zi)(zi)身(shen)特性的(de)反饋控制系統(tong)(tong)以使(shi)系統(tong)(tong)能按(an)照(zhao)一些設定的(de)標(biao)準(zhun)工作在最(zui)優狀態。

　　自(zi)適(shi)應控(kong)(kong)制的研究對(dui)象是具有不(bu)(bu)確定(ding)(ding)性的系統。自(zi)適(shi)應控(kong)(kong)制能修正(zheng)自(zi)己的特(te)性以適(shi)應對(dui)象和擾動(dong)的動(dong)態特(te)性的變化。 在反饋(kui)控(kong)(kong)制和最優控(kong)(kong)制中(zhong)，都(dou)假(jia)定(ding)(ding)被(bei)控(kong)(kong)對(dui)象是確定(ding)(ding)系統，然而在眾(zhong)多(duo)的工程實踐中(zhong)被(bei)控(kong)(kong)對(dui)象數學模型(xing)都(dou)是不(bu)(bu)確定(ding)(ding)系統，下面介紹一(yi)下確定(ding)(ding)系統和不(bu)(bu)確定(ding)(ding)系統：

　　1.1 確定(ding)系統(tong)(tong) 數(shu)學模(mo)型完全(quan)確定(ding)的系統(tong)(tong)(階次和參數(shu)已知(zhi))。在性(xing)能指標給定(ding)的前提下，系統(tong)(tong)設計(ji)的方法有三種： 根(gen)軌跡法 頻率特性(xing)法 狀態空(kong)間法

　　1.2 不(bu)(bu)確(que)(que)定(ding)(ding)系(xi)(xi)統 數(shu)(shu)(shu)學模型不(bu)(bu)完全確(que)(que)定(ding)(ding)的(de)(de)(de)(de)系(xi)(xi)統，階(jie)次確(que)(que)定(ding)(ding)參(can)(can)數(shu)(shu)(shu)不(bu)(bu)確(que)(que)定(ding)(ding)或者階(jie)次參(can)(can)數(shu)(shu)(shu)都不(bu)(bu)確(que)(que)定(ding)(ding)，工程實(shi)踐中的(de)(de)(de)(de)不(bu)(bu)確(que)(que)定(ding)(ding)性(xing)是(shi)(shi)大量存在(zai)的(de)(de)(de)(de)，這(zhe)(zhe)種不(bu)(bu)確(que)(que)定(ding)(ding)性(xing)有時表(biao)現(xian)在(zai)內部，有時表(biao)現(xian)在(zai)外(wai)(wai)部。 內部不(bu)(bu)確(que)(que)定(ding)(ding)： 結構或參(can)(can)數(shu)(shu)(shu)不(bu)(bu)能確(que)(que)切知道(dao)， 如散(san)熱系(xi)(xi)統， 化(hua)學反應(ying)速度。 外(wai)(wai)部不(bu)(bu)確(que)(que)定(ding)(ding)： 工序(xu)改變， 環(huan)境改變， 靜(jing)摩擦， 隨(sui)機干擾(rao)。 面對(dui)的(de)(de)(de)(de)這(zhe)(zhe)些(xie)客觀的(de)(de)(de)(de)各式各樣的(de)(de)(de)(de)不(bu)(bu)確(que)(que)定(ding)(ding)性(xing)， 如何綜合出(chu)適當的(de)(de)(de)(de)控制規(gui)律， 使得某一指定(ding)(ding)的(de)(de)(de)(de)性(xing)能指標達(da)到(dao)最(zui)優(you)和(he)次最(zui)優(you)，這(zhe)(zhe)就(jiu)是(shi)(shi)自(zi)適應(ying)控制要解決的(de)(de)(de)(de)問題。 當被控對(dui)象是(shi)(shi)不(bu)(bu)確(que)(que)定(ding)(ding)系(xi)(xi)統時，常規(gui)控制器不(bu)(bu)可能得到(dao)很好的(de)(de)(de)(de)控制品(pin)質。為(wei)此(ci)，需(xu)要設計(ji)一種特殊的(de)(de)(de)(de)控制系(xi)(xi)統，它能夠(gou)自(zi)動地補償在(zai)模型階(jie)次、參(can)(can)數(shu)(shu)(shu)和(he)輸入信(xin)號方(fang)面非預知的(de)(de)(de)(de)變化(hua)，這(zhe)(zhe)就(jiu)是(shi)(shi)自(zi)適應(ying)控制。

　　自適(shi)應控(kong)(kong)制(zhi)(zhi)要解決的(de)(de)問(wen)題就是(shi)修正自己的(de)(de)特性(xing)(例如綜合出(chu)適(shi)當的(de)(de)控(kong)(kong)制(zhi)(zhi)規律(lv))以(yi)使(shi)用(yong)對象和擾動(dong)的(de)(de)動(dong)態特性(xing)的(de)(de)變化，使(shi)某一(yi)性(xing)能指(zhi)標達到最優(you)或者次(ci)優(you)。簡而言之，自適(shi)應控(kong)(kong)制(zhi)(zhi)是(shi)一(yi)種帶有在(zai)線參(can)數識別的(de)(de)控(kong)(kong)制(zhi)(zhi)方法(fa)。

　　2 發展

　　自(zi)(zi)(zi)(zi)適(shi)(shi)應(ying)(ying)(ying)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)系(xi)(xi)(xi)統(tong)(tong)首(shou)先(xian)是(shi)(shi)由Draper和(he)Li在(zai)1951年(nian)(nian)提出(chu)的(de)，他們介紹了一(yi)(yi)種(zhong)能(neng)(neng)使性(xing)能(neng)(neng)特(te)性(xing)不(bu)確定的(de)內燃機(ji)達到(dao)(dao)最(zui)佳性(xing)能(neng)(neng)的(de)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)系(xi)(xi)(xi)統(tong)(tong)，這(zhe)(zhe)種(zhong)類型(xing)的(de)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)能(neng)(neng)力能(neng)(neng)自(zi)(zi)(zi)(zi)動(dong)的(de)達到(dao)(dao)最(zui)優的(de)操作點，所以(yi)叫做最(zui)優控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)或極值控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)。 而(er)自(zi)(zi)(zi)(zi)適(shi)(shi)應(ying)(ying)(ying)這(zhe)(zhe)一(yi)(yi)專業名詞(ci)是(shi)(shi)1954年(nian)(nian)由Tsien在(zai)《工程控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)論(lun)》一(yi)(yi)書(shu)中提出(chu)的(de)。 其后(hou)，在(zai)1955年(nian)(nian)Benner和(he)Drenick也提出(chu)一(yi)(yi)個(ge)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)系(xi)(xi)(xi)統(tong)(tong)具有“自(zi)(zi)(zi)(zi)適(shi)(shi)應(ying)(ying)(ying)”的(de)概念。 自(zi)(zi)(zi)(zi)適(shi)(shi)應(ying)(ying)(ying)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)發展(zhan)的(de)重(zhong)要標志是(shi)(shi)在(zai)1958年(nian)(nian)Whitaker及同事(shi)設計的(de)一(yi)(yi)種(zhong)自(zi)(zi)(zi)(zi)適(shi)(shi)應(ying)(ying)(ying)飛機(ji)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)系(xi)(xi)(xi)統(tong)(tong)。 1960年(nian)(nian)Li和(he)Van Der Velde提出(chu)的(de)自(zi)(zi)(zi)(zi)適(shi)(shi)應(ying)(ying)(ying)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)系(xi)(xi)(xi)統(tong)(tong)，它(ta)的(de)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)回路中用一(yi)(yi)個(ge)極限環使參數(shu)不(bu)確定性(xing)得到(dao)(dao)自(zi)(zi)(zi)(zi)動(dong)補(bu)償，這(zhe)(zhe)樣的(de)系(xi)(xi)(xi)統(tong)(tong)稱為自(zi)(zi)(zi)(zi)振蕩(dang)的(de)自(zi)(zi)(zi)(zi)適(shi)(shi)應(ying)(ying)(ying)系(xi)(xi)(xi)統(tong)(tong)。 Petror等人在(zai)1963年(nian)(nian)介紹一(yi)(yi)種(zhong)自(zi)(zi)(zi)(zi)適(shi)(shi)應(ying)(ying)(ying)系(xi)(xi)(xi)統(tong)(tong)，它(ta)的(de)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)輸入由開關(guan)函數(shu)或繼電器(qi)產生(sheng)，并以(yi)與(yu)參數(shu)值有關(guan)的(de)系(xi)(xi)(xi)統(tong)(tong)軌線不(bu)變性(xing)原理(li)為基(ji)礎來設計系(xi)(xi)(xi)統(tong)(tong)。這(zhe)(zhe)種(zhong)系(xi)(xi)(xi)統(tong)(tong)稱為變結構系(xi)(xi)(xi)統(tong)(tong)。 20世(shi)紀(ji)(ji)70年(nian)(nian)代，隨(sui)著控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)理(li)論(lun)和(he)計算(suan)機(ji)技術(shu)(shu)的(de)發展(zhan)，自(zi)(zi)(zi)(zi)適(shi)(shi)應(ying)(ying)(ying)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)理(li)論(lun)取得了重(zhong)大進展(zhan); 20世(shi)紀(ji)(ji)80年(nian)(nian)代以(yi)來自(zi)(zi)(zi)(zi)適(shi)(shi)應(ying)(ying)(ying)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)理(li)論(lun)和(he)設計方(fang)法得到(dao)(dao)了不(bu)斷(duan)發展(zhan)和(he)完善，再(zai)加上(shang)計算(suan)機(ji)技術(shu)(shu)的(de)發展(zhan)，自(zi)(zi)(zi)(zi)適(shi)(shi)應(ying)(ying)(ying)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)(zhi)(zhi)技術(shu)(shu)得到(dao)(dao)更大幅度擴展(zhan)。

　　3 應用

　　自適(shi)(shi)應(ying)控制最初是應(ying)用在航(hang)空航(hang)天領域(yu);隨著(zhu)計算機(ji)(ji)技(ji)術的(de)發展，自適(shi)(shi)應(ying)控制在光學跟蹤(zong)望(wang)遠鏡、化(hua)工、冶金(jin)、機(ji)(ji)械(xie)加工領域(yu)也(ye)成功的(de)應(ying)用;目前，自適(shi)(shi)應(ying)控制的(de)應(ying)用領域(yu)涉及到航(hang)空航(hang)天、航(hang)海、電力、化(hua)工、鋼鐵冶金(jin)、熱力、機(ji)(ji)械(xie)、林業、通信、電子、原子能、機(ji)(ji)器(qi)人和生(sheng)物(wu)工程。

　　4 分類

　　自(zi)(zi)(zi)(zi)適應(ying)(ying)控(kong)(kong)制(zhi)的(de)種(zhong)類(lei)很多，包括： 增(zeng)益自(zi)(zi)(zi)(zi)適應(ying)(ying)控(kong)(kong)制(zhi) 模(mo)(mo)型(xing)參(can)(can)考(kao)自(zi)(zi)(zi)(zi)適應(ying)(ying)控(kong)(kong)制(zhi)(MRAC) 自(zi)(zi)(zi)(zi)校正控(kong)(kong)制(zhi)(STC) 直接優化(hua)目標函數(shu)自(zi)(zi)(zi)(zi)適應(ying)(ying)控(kong)(kong)制(zhi) 模(mo)(mo)糊(hu)自(zi)(zi)(zi)(zi)適應(ying)(ying)控(kong)(kong)制(zhi) 多模(mo)(mo)型(xing)自(zi)(zi)(zi)(zi)適應(ying)(ying)控(kong)(kong)制(zhi) 自(zi)(zi)(zi)(zi)適應(ying)(ying)逆控(kong)(kong)制(zhi) 其(qi)中最主要(yao)的(de)，也是(shi)最常用的(de)當屬模(mo)(mo)型(xing)參(can)(can)考(kao)自(zi)(zi)(zi)(zi)適應(ying)(ying)控(kong)(kong)制(zhi)(model reference adaptive system，MRAS)和自(zi)(zi)(zi)(zi)校正控(kong)(kong)制(zhi)系統(self-tuning control system)，這是(shi)比較成熟的(de)兩(liang)類(lei)自(zi)(zi)(zi)(zi)適應(ying)(ying)控(kong)(kong)制(zhi)系統。這類(lei)自(zi)(zi)(zi)(zi)適應(ying)(ying)系統的(de)一個主要(yao)特點是(shi)在線辨(bian)識(shi)對象(xiang)數(shu)學模(mo)(mo)型(xing)的(de)參(can)(can)數(shu)，進而修改(gai)控(kong)(kong)制(zhi)器的(de)參(can)(can)數(shu)。

　　4.1 模型(xing)參(can)考(kao)(kao)(kao)自(zi)適應(ying)(ying)(ying)(ying)控(kong)(kong)制(zhi)(zhi)(zhi) 這(zhe)類自(zi)適應(ying)(ying)(ying)(ying)控(kong)(kong)制(zhi)(zhi)(zhi)系(xi)統(tong)(tong)(tong)設(she)計方法的理論基礎(chu)為(wei)局部參(can)數(shu)優化(hua)方法、李雅普(pu)(pu)諾夫(fu)穩定性理論和(he)(he)(he)波(bo)波(bo)夫(fu)(Popov)超穩定性理論。 模型(xing)參(can)考(kao)(kao)(kao)白適應(ying)(ying)(ying)(ying)控(kong)(kong)制(zhi)(zhi)(zhi)系(xi)統(tong)(tong)(tong)由參(can)考(kao)(kao)(kao)模型(xing)、被(bei)控(kong)(kong)對(dui)象、反(fan)饋控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)和(he)(he)(he)調(diao)整(zheng)(zheng)(zheng)控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)參(can)數(shu)的自(zi)適應(ying)(ying)(ying)(ying)機(ji)構等部分組成，其基本(ben)原理如下圖1所示。這(zhe)類控(kong)(kong)制(zhi)(zhi)(zhi)系(xi)統(tong)(tong)(tong)包括內(nei)回(hui)路(lu)和(he)(he)(he)外(wai)回(hui)路(lu)兩個回(hui)路(lu)。內(nei)環是由被(bei)控(kong)(kong)對(dui)象和(he)(he)(he)控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)組成的普(pu)(pu)通反(fan)饋回(hui)路(lu)，而控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)的參(can)數(shu)則(ze)由外(wai)回(hui)路(lu)調(diao)整(zheng)(zheng)(zheng)。參(can)考(kao)(kao)(kao)模型(xing)的輸(shu)出(chu)(chu)(chu) y m y_my m ? 直(zhi)接(jie)(jie)表示了對(dui)象輸(shu)出(chu)(chu)(chu)應(ying)(ying)(ying)(ying)當(dang)(dang)怎樣(yang)理想地響(xiang)應(ying)(ying)(ying)(ying)參(can)考(kao)(kao)(kao)輸(shu)人信(xin)號 r rr。 當(dang)(dang)參(can)考(kao)(kao)(kao)輸(shu)入(ru) r ( t ) r(t)r(t) 同時加到(dao)系(xi)統(tong)(tong)(tong)和(he)(he)(he)模型(xing)的入(ru)口時，由于對(dui)象的初始參(can)數(shu)未知，控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)的初始參(can)數(shu)不可(ke)能整(zheng)(zheng)(zheng)定得很好。故一開始，運行(xing)系(xi)統(tong)(tong)(tong)的輸(shu)出(chu)(chu)(chu)響(xiang)應(ying)(ying)(ying)(ying) y ( t ) y(t)y(t) 與(yu)(yu)模型(xing)的輸(shu)出(chu)(chu)(chu)響(xiang)應(ying)(ying)(ying)(ying) y m ( t ) y_m(t)y m ? (t) 是不可(ke)能完全一致(zhi)，結果將產(chan)生偏(pian)差信(xin)號 e ( t ) e(t)e(t)，故可(ke)由 e ( t ) e(t)e(t) 驅動自(zi)適應(ying)(ying)(ying)(ying)機(ji)構來產(chan)生適當(dang)(dang)調(diao)節作(zuo)用(yong)，直(zhi)接(jie)(jie)改變(bian)控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)的參(can)數(shu)，從(cong)而使系(xi)統(tong)(tong)(tong)的輸(shu)出(chu)(chu)(chu) y ( t ) y(t)y(t) 逐步與(yu)(yu)模型(xing)輸(shu)出(chu)(chu)(chu) y m ( t ) y_m(t)y m ? (t) 接(jie)(jie)近，直(zhi)到(dao) y ( t ) = y m ( t ) y(t) = y_m(t)y(t)=y m ? (t) 為(wei)止(zhi)，當(dang)(dang) e ( t ) = 0 e(t)=0e(t)=0 后(hou)，自(zi)適應(ying)(ying)(ying)(ying)調(diao)整(zheng)(zheng)(zheng)過程就自(zi)動停(ting)止(zhi)，控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)參(can)數(shu)也就自(zi)動整(zheng)(zheng)(zheng)定完畢。 模型(xing)參(can)考(kao)(kao)(kao)自(zi)適應(ying)(ying)(ying)(ying)控(kong)(kong)制(zhi)(zhi)(zhi)(MRAC)可(ke)以看(kan)作(zuo)是 參(can)考(kao)(kao)(kao)模型(xing)+控(kong)(kong)制(zhi)(zhi)(zhi)器(qi)(qi)+自(zi)適應(ying)(ying)(ying)(ying)率三個部分。

　　4.2 自校正控(kong)(kong)制(zhi)(zhi) 自校正控(kong)(kong)制(zhi)(zhi)系統(tong)可以設想(xiang)由(you)兩個環(huan)路(lu)組(zu)成(cheng)(cheng)，其典型結構(gou)如下圖2所示(shi)。 該調節(jie)器(qi)(qi)(qi)的內(nei)環(huan)包括被控(kong)(kong)對(dui)(dui)(dui)象和一(yi)個普通(tong)的線性反饋(kui)調節(jie)器(qi)(qi)(qi)，外(wai)環(huan)則由(you)一(yi)個遞推參(can)(can)數估(gu)(gu)計器(qi)(qi)(qi)和一(yi)個設計機構(gou)所組(zu)成(cheng)(cheng)，其任務是辨識過(guo)(guo)程參(can)(can)數，再按選(xuan)定的設計方法綜合出(chu)控(kong)(kong)制(zhi)(zhi)器(qi)(qi)(qi)參(can)(can)數，用(yong)以修(xiu)改內(nei)環(huan)的控(kong)(kong)制(zhi)(zhi)器(qi)(qi)(qi)。這類(lei)系統(tong)的特點是必須對(dui)(dui)(dui)過(guo)(guo)程或(huo)者(zhe)被控(kong)(kong)對(dui)(dui)(dui)象進行在線辨識(估(gu)(gu)計器(qi)(qi)(qi))，然后(hou)用(yong)對(dui)(dui)(dui)象參(can)(can)數估(gu)(gu)計值和事先規定的性能(neng)指(zhi)標在線綜合出(chu)調節(jie)器(qi)(qi)(qi)的控(kong)(kong)制(zhi)(zhi)參(can)(can)數，并根據此控(kong)(kong)制(zhi)(zhi)參(can)(can)數產生(sheng)的控(kong)(kong)制(zhi)(zhi)作用(yong)對(dui)(dui)(dui)被控(kong)(kong)對(dui)(dui)(dui)象進行控(kong)(kong)制(zhi)(zhi)。經過(guo)(guo)多次地辨識和綜合調節(jie)參(can)(can)數，可以使(shi)系統(tong)的性能(neng)指(zhi)標趨于(yu)最優。 自校正控(kong)(kong)制(zhi)(zhi)可以看(kan)作是參(can)(can)數估(gu)(gu)計+控(kong)(kong)制(zhi)(zhi)器(qi)(qi)(qi)這兩部分(fen)組(zu)成(cheng)(cheng)。

　　5 主要研究

　　無(wu)論(lun)是時不變(bian)(bian)(bian)線性(xing)系統(tong)，還是時變(bian)(bian)(bian)非(fei)線性(xing)系統(tong)，它們與(yu)自(zi)適應(ying)機(ji)構所構成的自(zi)適應(ying)控制系統(tong)都是非(fei)線性(xing)時變(bian)(bian)(bian)系統(tong)，分析這(zhe)類(lei)系統(tong)的性(xing)能(neng)是很困難(nan)的。

　　1 穩(wen)(wen)定(ding)性(xing) 穩(wen)(wen)定(ding)性(xing)問題是一切(qie)控(kong)制系(xi)(xi)統(tong)(tong)的核心問題。因此，設計自適應控(kong)制系(xi)(xi)統(tong)(tong)應以保(bao)證(zheng)系(xi)(xi)統(tong)(tong)全局穩(wen)(wen)定(ding)為(wei)原則。如今，隨著(zhu)模型參考自適應控(kong)制的發展，各(ge)種(zhong)各(ge)樣的自適應控(kong)制律會不斷(duan)誕生，要(yao)保(bao)證(zheng)系(xi)(xi)統(tong)(tong)全局穩(wen)(wen)定(ding)也(ye)很困難，特別是因為(wei)系(xi)(xi)統(tong)(tong)是本質非線性(xing)時變的，故當系(xi)(xi)統(tong)(tong)存在未建模動態或(huo)隨機(ji)干擾時，要(yao)證(zheng)明自適應控(kong)制系(xi)(xi)統(tong)(tong)的穩(wen)(wen)定(ding)性(xing)就更困難了。

　　2 收(shou)斂性 對于(yu)一(yi)些(xie)自適應系統(tong)收(shou)斂性的結論(lun)都(dou)是在一(yi)些(xie)相當強的假設條件下獲得(de)的，并(bing)且與具(ju)體的算(suan)法(fa)密切相關。因所(suo)使用(yong)的收(shou)斂性分析方法(fa)缺乏普適性，因而(er)不(bu)能推廣到稍微(wei)復雜的系統(tong)模型上(shang)。

 　　3 魯(lu)棒性(xing)(xing) 目(mu)前，參(can)考模(mo)(mo)型自適(shi)應控(kong)制(zhi)系統(tong)(tong)一般都是(shi)針(zhen)對(dui)(dui)(dui)被(bei)(bei)控(kong)對(dui)(dui)(dui)象(xiang)結構已知而(er)(er)參(can)數未知的(de)(de)(de)情況進行設計(ji)的(de)(de)(de)，而(er)(er)實際被(bei)(bei)控(kong)對(dui)(dui)(dui)象(xiang)結構往(wang)往(wang)難以確切知道，所獲得(de)的(de)(de)(de)對(dui)(dui)(dui)象(xiang)特性(xing)(xing)中(zhong)常常未能包括系統(tong)(tong)的(de)(de)(de)難以描述的(de)(de)(de)寄生高頻成分，即未建(jian)模(mo)(mo)動(dong)態。計(ji)算機仿真表明，這(zhe)種未建(jian)模(mo)(mo)型動(dong)態可能引起自適(shi)應控(kong)制(zhi)系統(tong)(tong)的(de)(de)(de)不穩定，關鍵原因是(shi)自適(shi)應控(kong)制(zhi)系統(tong)(tong)是(shi)非線性(xing)(xing)時變的(de)(de)(de)，，而(er)(er)對(dui)(dui)(dui)于線性(xing)(xing)反饋控(kong)制(zhi)系統(tong)(tong)，只有(you)設計(ji)的(de)(de)(de)系統(tong)(tong)有(you)足夠的(de)(de)(de)穩定裕量，這(zhe)種未建(jian)模(mo)(mo)動(dong)態是(shi)不致于破壞系統(tong)(tong)穩定性(xing)(xing)的(de)(de)(de)。這(zhe)就(jiu)提出了自適(shi)應控(kong)制(zhi)的(de)(de)(de)魯(lu)棒性(xing)(xing)問題(ti)。

　　4 性(xing)能(neng)指標 一個自適應控制系統(tong)能(neng)很好地(di)工(gong)作，不(bu)僅要求所(suo)設(she)計的(de)系統(tong)穩(wen)定，而且(qie)還有滿足一定的(de)性(xing)能(neng)指標要求。由于自適應控制系統(tong)是(shi)非線性(xing)時變的(de)，初始條件的(de)變化(hua)或未建模動態(tai)的(de)存(cun)在都勢必要改(gai)變系統(tong)的(de)運(yun)動軌跡(ji)，因(yin)此，分析(xi)自適應控制系統(tong)的(de)動態(tai)品質是(shi)極(ji)其困難的(de)。目前，這方面的(de)成果還很少見。

　　6 特點

　　1、控制(zhi)器(qi)(qi)可調 相對于常規反饋控制(zhi)器(qi)(qi)固(gu)定的結構和參數(shu)，自適(shi)應(ying)(ying)控制(zhi)系統的控制(zhi)器(qi)(qi)在控制(zhi)的過(guo)程(cheng)中一般是根(gen)據一定的自適(shi)應(ying)(ying)規則，不斷(duan)更改或(huo)變(bian)動的;

　　2、增加了自(zi)適(shi)應回(hui)路(lu) 自(zi)適(shi)應控制(zhi)系統(tong)(tong)(tong)在常規反(fan)饋控制(zhi)系統(tong)(tong)(tong)基礎(chu)上增加了自(zi)適(shi)應回(hui)路(lu)(或稱自(zi)適(shi)應外環)，它的主要作用(yong)就是根據系統(tong)(tong)(tong)運行情況(kuang)，自(zi)動調整控制(zhi)器，以適(shi)應被控對象(xiang)特性的變化;

　　3、適(shi)用(yong)對(dui)(dui)象 自適(shi)應控制(zhi)適(shi)用(yong)于被(bei)控對(dui)(dui)象特性(xing)未知(zhi)或(huo)擾(rao)動特性(xing)變化范圍很大，同時又要求經常保持(chi)高性(xing)能(neng)指標的一(yi)類系統，設計時不需要完(wan)全(quan)知(zhi)道被(bei)控對(dui)(dui)象的數學模型(xing)。