【正文】
義PID控制器的階次更為靈活,其積分和微分部分的階次為實數(shù),并且認為傳統(tǒng)的整數(shù)階PID控制器是分數(shù)階控制器的一種特例。另外根據(jù)加拿大一項統(tǒng)計發(fā)現(xiàn)97%的造紙廠控制設(shè)備使用的是PI控制器。由于分數(shù)階控制器在計算機中的實現(xiàn)手段主要還是借用整數(shù)階逼近的方式來實現(xiàn),因此很多學(xué)者對這種近似方法進行了分析,Blas “Tustin”方法對分數(shù)階微分及積分算子進行離散研究[50];Igor Podlubny 在文獻[51]中專門對分數(shù)階控制器在計算機中實現(xiàn)的問題進行了討論;YangQuan Chen 等人利用脈沖響應(yīng)不變原理得到了分數(shù)階算子的高階近似方法[553]。其中,Y. Q. Chen等人對分數(shù)階魯棒控制進行了深入的研究,利用Lyapunov不等式對分數(shù)階魯棒穩(wěn)定區(qū)間問題進行了探討[26]。Igor Podlubny從理論上提出了一個廣義的分數(shù)階PID控制器的結(jié)構(gòu)及傳遞函數(shù),被稱為控制器[19],其中積分器和微分器的階次均為實數(shù)??偨Y(jié)起來,分數(shù)階控制器較之傳統(tǒng)控制器具有以下明顯特點:(1)對于分數(shù)階被控對象,利用分數(shù)階控制器控制性能優(yōu)于傳統(tǒng)的整數(shù)階控制器;(2)分數(shù)階控制器對被控對象參數(shù)的變化具有較強的魯棒性;(3)當(dāng)用整數(shù)階微積分對某些系統(tǒng)建模比較復(fù)雜時,分數(shù)階微積分往往能更好的描繪系統(tǒng)的特性,且系統(tǒng)傳遞函數(shù)更為簡單。那么從這種從屬關(guān)系可以設(shè)想,整數(shù)階微積分能夠描述的系統(tǒng)分數(shù)階微積分肯定能夠描述,但是分數(shù)階微積分描述的系統(tǒng)特性用整數(shù)階微積分來描述將會變得特別復(fù)雜或者根本無法得到準確的整數(shù)階系統(tǒng)模型。但是分數(shù)階微積分的發(fā)展較之整數(shù)階微積分仍然很慢,主要是由于分數(shù)階微積分的定義很多,在不同的領(lǐng)域沒有一個統(tǒng)一的數(shù)學(xué)定義。 Caputo定義下的Laplace變換Caputo定義下的分數(shù)階微分因其在初始條件的導(dǎo)數(shù)為0,具有明確的物理意義,在實際中應(yīng)用較為廣泛。對于一個普通函數(shù)的Laplace變換為 ()對于分數(shù)階函數(shù)而言,根據(jù)不同的定義,其Laplace變換存在著差別,下面將介紹兩種常用定義的Laplace變換。還有就是Caputo定義對常數(shù)的導(dǎo)數(shù)是有界的,即常數(shù)的導(dǎo)數(shù)為0,而RiemannLiouville定義對常數(shù)的導(dǎo)數(shù)卻是無界的。因此,在應(yīng)用方面的發(fā)展受到阻礙。另外地,RiemannLiouville 定義在工程中得到廣泛應(yīng)用,還有一個重要條件就是它要求可積。很多時候分數(shù)階后向差分以一種極值的情況出現(xiàn)是很不利于實際應(yīng)用的。廣義MittagLeffler函數(shù)定義為 ()其中??梢员硎境?, () MittagLeffler 函數(shù) MittagLeffler函數(shù)在微分方程中起著非常重要的作用。nwaldLetnikov定義、RiemannLiouville定義、Caputo定義。因此隨著分數(shù)階微積分從一個純數(shù)學(xué)問題開始演變成一種系統(tǒng)建模的工具,再到推動分數(shù)階控制理論的發(fā)展,必須承認這是分數(shù)階微積分理論和控制理論共同良性發(fā)展的一條必然之路,它們之間互相提供了大量的、新的研究方向和發(fā)展空間。這一優(yōu)勢在結(jié)構(gòu)力學(xué),電學(xué),流體力學(xué)等方面體現(xiàn)得更為明顯。 首次指出大量分數(shù)維的現(xiàn)象存在于自然界和許多技術(shù)科學(xué)中,由此分數(shù)階微積分作為分數(shù)階動力學(xué)的基礎(chǔ)和有力工具獲得了極大的發(fā)展。當(dāng),,時有 () 隨著時間的推移越來越多的數(shù)學(xué)家展示出了對分數(shù)階微積分濃厚的興趣,并在此道路上作出了巨大的貢獻[1]。隨著人們對分數(shù)階微積分認識的不斷加深,越來越多的人開始認識到分數(shù)階微積分對近代科學(xué)高速發(fā)展具有的價值和意義。 autotuning。 high plexity in parameter calculation in tuning the controllers and the lack of fair parison with the integer order controllers. Therefore, it is of practical importance to develop FOPID tuning methods and explore its potential applications in engineering. Robustness of a control system is a very important topic in control theory, which should be considered during the controller design. In real world control system, variations in system’s properties and physical parameters are unavoidable due to many factors, such as environment changes. To avoid the performance change due to parameter variations, the robustness of the controller is the central topic on which this dissertation focuses. FOPID focused in this dissertation is more flexible in achieving robust performance. The controlled systemunder FOPID controller not only can meet the stability requirement, but also meet the robust requirement with respect to uncertainties in system model such as gain to time constant variations. This dissertation focuses on developing a systematic fractional order PID controller tuning rule to achieve system performance robustness against variations in system gain and time constant DC motor experiment is used to validate the developed tuning methods. The main contribution of this thesis is on the development of FOPID robust tuning rule based on different controlled systems Meanwhile, for practical use in industry, an autotuning design method has been developed. Both simulation and experimental results are included to illustrate the developed FOPID tuning methods. Specifically, the research results in this dissertation include:(1) FOPID tuning rules based on the system robustness requirement against system gain variations is developed. Systematic tuning rules about FOPD, FO[PD], FOPI,FO[PI] are derived. Simulation results are presented to verify that the performance of the designed fractional order controller is better than the integer order PID controller.(2) A FO[PD] tuning rule based on systemrobustness requirement with respect to time constant uncertainty is developed for the first time. Detailed mathematic derivations are presented and the requirements on the existence of solution in the tuning equations are studied, too. To simplify the putational method for online implement, an online putational method is developed. Results of both simulation and experiments are included to show the correctness and effectiveness of this new tuning rule.(3) For unknown, stable, minimum phase systems, a set of autotuning rules for four types of FOPID controllers: FOPI, FO[PI], FOPD, FO[PD] having the desirable isodamping property are derived. A relay feedback experiment method is introduced for easy implemention of the fractional order PID controller in real world control systems.(4) We extend the fractional order controller application areas to synchronized tracking control systems. We study how fractional order controller can better synchronize the multiple motion control systems. Simulation results are presented to verify that this fractional order control method can improve mutisystem synchronization. (5) For the first time the FOPID controller has been implemented on the LabVIEW experiment platform. The experiment results have verified that the FOPID can offer outstanding performance. Key words: Fractional calculus, fractional order PID。(4)根據(jù)FOPID控制器的性能特點,開拓了分數(shù)階控制器的應(yīng)用空間,討論了FOPID控制器整定算法在同步追蹤控制系統(tǒng)中的應(yīng)用。另外,為了簡化計算方法以及實現(xiàn)在線計算,本文還提出了一種快速在線計算參數(shù)的方法。針對電機位置伺服系統(tǒng)模型以及速度伺服系統(tǒng)模型,系統(tǒng)地提出了FOPD、FO[PD]、FOPI、FO[PI]的整定方法。本文的貢獻主要是利用FOPID控制器的結(jié)構(gòu)特點,提出了針對不同控制對象的FOPID控制器參數(shù)魯棒性的整定方法。在現(xiàn)實的控制問題中,系統(tǒng)特性或參數(shù)的變化常常是不可避免的,因為系統(tǒng)在運行過程中受到環(huán)境等因素的影響將會引起系統(tǒng)參數(shù)的飄移。FOPID控制器結(jié)構(gòu)上的特點使得其具有傳統(tǒng)整數(shù)階PID控制器無法比擬的優(yōu)勢。實際上自然界中許多系統(tǒng)特性用分數(shù)階微積分來描述更為簡單并更能真實的反映事物的本質(zhì)規(guī)律。本學(xué)位論文屬于保密□,在 年解密后適用本授權(quán)書。對本文的研究做出重要貢獻的個人和集體,均已在文中以明確方式標明。除了文中特別加以標注引用的內(nèi)容外,本論文不包含任何其他個人或集體已經(jīng)發(fā)表或撰寫的成果作品。本人授權(quán)湖南大學(xué)可以將本學(xué)位論文的全部或部分內(nèi)容編入有關(guān)數(shù)據(jù)庫進行檢索,可以采用影印、縮印或掃描等復(fù)制手段保存和匯編本學(xué)位論文?,F(xiàn)有大量文獻提到,利用分數(shù)階微積分能夠?qū)υS多事物進行更精確的數(shù)學(xué)建模,這些分析結(jié)論在很大程度上推動了分數(shù)階理論在工程應(yīng)用方面的發(fā)展。值得注意的是,F(xiàn)OPID(Fractional Order Proportion Integration Differentiation)控制器的誕生,為分數(shù)階控制器的應(yīng)用開辟了一個新的領(lǐng)域??刂评碚撝杏幸粋€重要的課題,也是一個在控制器設(shè)計時需要考慮的問題——系統(tǒng)魯棒性。因此,本文對控制系統(tǒng)中被控對象的系統(tǒng)增益以及時間常數(shù)的魯棒性進行了研究,提出了一系列針對系統(tǒng)參數(shù)魯棒性的分數(shù)階控制器整定方法,并通過電機等電氣工程的實際應(yīng)用方面的分析進行了驗證。 本文的具體研究成果包括:(1)設(shè)計了一種針對系統(tǒng)增益魯棒性的FOPID控制器參數(shù)整定公式。對整定方程的數(shù)值計算方法進行了深入的研究,給出了整定方程組解的存在性的約束條件。在未知被控對象的前提下設(shè)計了一種繼電反饋測試實驗,從而實現(xiàn)了該方法在控