科技部補助專題研究計畫出席國際學術會議心得報告
日期：108 年 9 月 3 日
一、 參加會議經過
此次參加的會議名稱為 2019 第 15 屆國際智慧無人機系統會議（The 15th In-ternational Conference on Intelligent Unmanned Systems）。該會議對於控制理論與應 用學者來說，是場必須參加的國際重要盛會之一。整體會議所涉及之議題包含了 探討無人機系統之最新研究成果，及世界各地等先進無人機技術及其相關應用，
並特別著重於探討無人機系統的未來發展方向和趨勢。該會議今年是北京科技大 學（University of Science and Technology Beijing）及淡江大學（Tamkang University）
主辦，並由 International Society of Intelligent Unmanned Systems、International So-ciety of Mechatronic Engineering、Office of Naval Research Global、中國自動化學會 青年工作委員會（Youth Academic Committee of Chinese Association of Automation）、 IEEE SMC Beijing Capital Region Chapter、IEEE SMC TC on Autonomous Bionic 計畫編號 MOST 108－2221－E－006－211－
計畫名稱 具輸出約束之高階非線性系統有限時間穩定化控制：一種階層齊次
(英文) Fixed-time stabilization for a class of uncertain nonlinear sys-tems
Robotic Aircraft、北京市高校高精尖學科（Beijing Top Discipline for Artificial Intel-ligent Science and Engineering, University Science and Technology Beijing）、School of Automation and Electrical Engineering, University of Science and Technology Beijing、
Institute of Artificial Intelligence, University of Science and Technology Beijing 等單位 協辦。會議期間為西元 2019 年 8 月 27 日至 8 月 29 日，地點為北京科技大學、天 宮大廈 B 座樓（The Third Floor Corridor of the Techart Plaza）。本人在 8 月 27 日先 由台南出發至桃園國際機場，搭乘飛機（中國國際航空）直達飛抵中國北京首都 國際機場。本人的論文報告日期被安排在 8 月 28 日下午 1 點 30 分開始得分組報 告（由本人之學生：丁齊萱進行報告），主題為 Space Robotic Systems Modelling and Autonomous Control。在發表論文前，本人提前至會場參觀世界各地先進的研究，
對於世界各國目前對於無人機技術與其應用之研究成果及發展留下深刻之印象。
此行開拓了個人的視野，自覺收穫豐碩。會議期間本人也遊覽北京科技大學校園，
對於北京科技大學校園及其各大研究中心的磅礡建築，感到無比的讚嘆。對於此 次前往參加會議，我們不僅能夠學習到國際頂尖無人機設計、分析、控制技術與 應用，還能夠受到諸多國際學者對於研究的認真與努力態度的薰陶，收穫甚多。
結束會議與參訪活動後我們於 9 月 1 日下午搭飛機按原路線飛返台灣。
二、 與會心得
參加此次國際智慧無人機系統會議的各國專家學者甚多，包含有中國大陸、
印度、美國、越南、韓國等國家，探討的主題從無人機系統設計技術之開發，到 其整體系統之控制分析與其在各類實際問題上之應用等等應有盡有，內容涵蓋相 當廣泛。在這次會議中，我們被安排在 28 日的下午進行口頭。在報告完畢後，許 多學者向我們（由本人之學生：丁齊萱，做報告）提出了許多有價值的問題，並 在會後我們做了更進一步的討論，在討論後我們也獲得了共同的解答。此外，在 此次會議中，我們與多位在無人機控制技術發展等領域中，極其頂尖的專家學者 們見面，並向其自我介紹，並在交談中獲得了許多寶貴的研究想法與觀念，自覺 收穫良多。在會議期間我們也前往聆聽與自己研究領域相關的主題，同時觀摩各
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國學者專家呈現研究成果的方式，並從中學習做為往後若再次獲得發表論文機會 時的最好準備。參加此次會議除了能夠親自目睹及體會著名學者的風範及執著、
認真的研究精神，萌生見賢思齊與自我期許的成長動力，同時能夠增進自己在國 際會議發表論文的膽識並獲得國際學術界最新的研究動態。在會議期間許多研究 無人機系統的先進前輩所提出的問題及給予之意見不但具體，且往往能明確地點 出問題之所在，進而提供進一步的研究方向與可能解答之輪廓，個人自覺收穫甚 多。在未來，希望自己能有擁有更多的機會參與類似的國際會議。在這次的會議 後，我們帶回大會給予的論文資料，使我們可以盡覽此次會議的所有成果。在此 願再一次的感謝科技部的經費補助，使我們能順利的參與這次的研究成果發表饗 宴。
三、 發表論文之摘要
This paper investigates the problem of fixed-time stabilization for a class of multivaria-ble uncertain nonlinear systems. A new approach is proposed by skillfully revamping the technique of adding a power integrator whereby a state feedback controller and a suitable Lyapunov function for verifying fixed-time convergence can be explicitly con-structed to render the closed-loop system fixed-time stable. The novelty of this paper owes to the develop-ment of a subtle strategy that provides a new solution to the prob-lem of fixed-time stabilization for multivariable nonlinear systems. Finally, the devel-oped approach is applied to the attitude stabilization of a spacecraft to show the effec-tiveness of the resultant controller.
四、 建議
此行前往大陸北京科技大學參與本次會議後，我們深感學術交流與國際視野 開拓的重要性。此外，由於世界各國，特別是中國大陸，等諸多大學資金充裕，
研究資源豐富，在各專業領域中不乏有知名專家學者。在與其交流的過程中，不 僅能夠享受到高手交流之樂，更能了解每位專家所關注的焦點，使本人對整體研
究趨勢有更深入的了解，有助於本人掌握新的研究方向。有鑑於此，本人亦誠心 地建議科技部或相關單位，往後能多鼓勵並盡可能地補助國內年輕學者或博士研 究生，使其能夠多與國際學者們進行交流訪問或參與國際學術會議，藉此開拓其 國際視野並邁向國際，同時提高臺灣之國際學術能見度。
五、 攜回資料名稱及內容
大會論文集隨身碟一枚及紙本一本。
六、 發表論文之全文 詳見最末頁。
附件一：（議程）
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附件二：（參與會議照片）
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ICIUS 2019, Beijing, China Paper ID 26
Abstract—This paper investigates the problem of fixed-time stabilization for a class of multivariable uncertain nonlinear sys-tems. A new approach is proposed by skillfully revamping the technique of adding a power integrator whereby a state feedback controller and a suitable Lyapunov function for verifying fixed-time convergence can be explicitly constructed to render the closed-loop system fixed-time stable. The novelty of this paper owes to the development of a subtle strategy that provides a new solution to the problem of fixed-time stabilization for multivariable nonlinear systems. Finally, the developed approach is applied to the attitude stabilization of a spacecraft to show the effectiveness of the resultant controller.
Keywords—Uncertain nonlinear systems, adding a power inte-grator technique, fixed-time stabilization.
I. INTRODUCTION
HE stabilization control of nonlinear system has always been crucial in performing additional control tasks, such as output tracking, disturbance attenuation and/or decoupling.
Global asymptotic stabilization of nonlinear systems has gained tremendous progress due to the development of mathematical tools, including backstepping design [1], feedback linearization [2], sliding mode control [3, 4], fuzzy control [5, 6], has tremendous progress by mathematical tools.
As is well-known, finite-time stabilization is more attrac-tive compared with asymptotic stabilization [7] because the systems with finite-time convergence usually exhibit superi-or properties [7-10], which are rather impsuperi-ortant fsuperi-or demand-ing applications. Bedemand-ing aware of these features, the fi-nite-time stabilization problem has been intensively studied, and numerous interesting results have been proposed in the past decades [11-15]. For instance, owing to the benefits including fast response and ease of implementation, terminal sliding mode control design [14] is one of most important techniques for finite-time stabilization of nonlinear system.
By constructing a discontinuous controller while design a suitable nonlinear sliding surface, the phase of terminal sliding mode can be achieved in finite-time, thereby guaran-teeing finite-time stabilization of the closed-loop system [14-16].
It should be mentioned that the information of initial states is critical for the settling-time estimates of finite-time stabilization schemes; however, the availability of initial states will prevent us from applying finite-time schemes [17,
1C.-C. Chen is an Assistant Professor with Department of Systems and Naval Mechatronic Engineering, National Cheng Kung University, Tainan 70101, Taiwan (e-mail: ccchenevan@mail.ncku.edu.tw).
2C.-H. Ding and G.-S. Chen are master students with Department of Systems and Naval Mechatronic Engineering, National Cheng Kung Uni-versity, Tainan 70101, Taiwan.
18]. Fortunately, the notion of fixed-time stability together with its Lyapunov-like criteria has been recently presented in the seminal work [17] in which the potential obstruction of finite-time schemes was resolved effectively. To be more specific, as stated in [17], by fixed-time controller design, it implies global uniform finite-time stability while providing a settling time function to be uniformly bounded by a tunable constant, which independent of initial states [17, 18-24].
Due to the complexity of multivariable nonlinear systems and the lack of systematic strategies for ensuring the fixed-time convergence, the problem on how to design a fixed-time stabilizing controller for multivariable nonlinear systems remains unclear and largely open. In this paper, by introducing extra manipulations in the feedback domination to delicately revamp the technique of adding a power inte-grator [18], a new approach is developed to the synthesis the fixed-time stabilizer together with the Lyapunov function for multivariable uncertain nonlinear systems.
II. PRELIMINARIES
A. Problem Formulation
Consider a class of nonlinear systems described by 𝐱 𝐱𝟐 worth mentioning that a very large class of physical systems can be represented by system (1). Besides, the solutions of system (1) are understood in the sense of Filippov [26] since the control input 𝐮 𝐮 𝑡, 𝐱 is admitted to be discontinu-ous (piecewise continudiscontinu-ous) and 𝐝 𝑡, 𝐱 is assumed to be piecewise continuous and bounded as follows.
Assumption 1. There exists a constant 𝜌 0 such that
|𝑑 𝑡, 𝐱 | 𝜌 for all 𝑡, 𝐱 ∈ ℝ ℝ and 𝑖 1, . . . , 𝑛.
Under Assumption 1, the main objective of this paper is to design a controller 𝐮 𝐮 𝑡, 𝐱 that renders the origin of system (1) fixed-time stable in the sense of the following definition.
Definition 1 ([17]). Consider the following nonlinear system 𝐱 𝐠 𝑡, 𝐱