Earticle

지상 무인 차량(UGV), 무인기(UAV), 무인수상정(USV), 무인잠수정(UUV), 로봇 등과 같은 다중 무인체가 대형을 이루면서 군집 주행을 할 때 충돌회피 문제는 다중 에이전트 시스템에서 기본적으로 구현해야 하는 것으로 중요하게 인식되었다. 다중무 인체들은 가까운 미래에 생화학 오염지역이나 위험한 전투지역에서의 신속하게 투입되어 주어진 임무를 수행할 것이다. 다중 무인체가 편대를 이루어 출발지점에서 목표점인 임무 지역으로 이동할 때 자율주행을 할 수 있는 선도-추종 대형제 어를 적용하고, 다중무인체가 군집 자율주행할 때 갑자기 동적장애물 등이 나타나거나 주행 경로상에 고정장애물이 존재할 경우 이를 회피하기 위해 인공전위장을 이용한다. 지상전에서 다중 무인체의 장애물 회피 시스템에 대한 대형제어 알고리즘 성능을 평가하기 위해, 다중 무인체가 각각 3대, 5대, 7대, 그리고 장애물이 각각 0개, 1개, 3개, 5개인 경우에 대해 이들을 조합한 여러 가지 군집 자율주행상황을 시뮬레이션하였다.

It has been importantly recognized that the collision avoidance problem of multiple unmanned vehicles(MUVs) such as UGV, UAV, USV, UUV, Robot, etc. for platoon autonomous navigation in dynamic environments should be implemented basically in multiple agent systems. In the near future, they will be dispatched quickly and carry out their assigned tasks in biochemical contaminated area or dangerous combant areas. When multiple unmanned vehicles form a platoon formation and move from the starting point to the target point, leader-follower formation control that can autonomously navigate is applied. When multiple unmanned vehicles are autonomously driving in clusters, if a dynamic obstacle suddenly appears or there is a fixed obstacle on the driving path, artificial potential is used to avoid them. In order to check the performance of the formation control algorithm for the obstacle avoidance system of multiple unmanned vehicles in ground warfare, in the case of multiple unmanned vehicles with 3, 5, 7, and 0, 1, 3, and 5 obstacles, respectively, various platooning autonomous navigation situations were simulated by combining them.

The term "jangdan (lit. "long and short") indicates a number of musical features in Korean traditional music, and among one of these characters, it refers to "rhythmic cycle". I have already revealed the rhythmic cycle of jangdan in relation to a framework of Chomskian generative/ transformational grammar of language in my article (see "A study of syntax-semantics of jangdan with special reference to naedeureum of Pansori" 2000), and my basic findings ate provided by the followings: (1) Rhythmic cycle is formed by the syntactic roles by which rhythmic constituents is fixed. (2) The syntactic rule is governed by which the rhythmic constituents of lower level, the two- Collections or three-collections on the beats of the lower level, and then is constructed by their upper level on the beats of the upper level, thus forming their three levels on the beats of the three levels. (3) The "syntactic structure of jangdan" can be constructed by "collective structure" of the rhythmic constituents that generates its beats of the rhythmic cycle. There are two kinds of musical genres which are constructed by (ⅰ) one kind of the 'syntactic structure of jangdan rhythm' that I would call a "deep structure" and (ⅱ) several kinds of the 'syntactic structure of jangdan rhythm' called a "surface structure" in Korean music. In the latter, such repertoire as Pansori (Korean narrative song with an accompaniment of the drum) and Sanjo (highly improvised solo instrumental music) that are consisted of several kinds of the 'syntactic structure of jangdan rhythm', are formed by a number of syntactic structure of the jangdan rhythm, but their underlying structures are based on one kind of the syntactic structure of jangdan rhythm. In contrast, such repertoire as Seodo jwachang (songs of Sea provinces in sitting position) and ipchang (songs that sing in standing position) are formed by several kinds of the syntactic structure of jangdan rhythm, thus its underlying structure is not seen as the case of one kind of the syntactic structure of jangdan rhythm. This paper aims to investigate how these two kinds of jangdan structures are constructed differently: in the case of the deep structure of jangdan rhythm, whether it is underlying or not represented in two musical performances: jungjungmori (jangdan formation based on a bit fast tempo) 'Whachotaryeong' in Pansori Shimcheongga (song for Shimcheong) and 'Chohanga' in Seodo jwachang respectively. The results of the investigation of two musical performances can be offered: In terms of a set of rules, the first case in naedeureum (initial jangdan in order to introduce the song) necessarily has fixed rules that present an "idiomatic structure" or its equivalent regular deep structure, whereas the second case has no fixed rules to be presented. In the example of the first case, when the syntactic structure of jangdan rhythm changes a number of ways, a length of rhythmic cycle is mostly regular. In this process when the rhythmic cycle changes, the length of the total phrases becomes a 'common multiple' of the deep structure represented by naedeureum. In the second case, when the rhythmic cycle of jangdan changes irregularly, the length of the total phrases is not yielded the common multiple. The first case, when the cycle of syntactic structure of jangdan rhythm changes, the syntactic structure of jangdan rhythm which is accompanied by percussion instruments does not change. In contrast, the second case, when the syntactic structure of jangdan rhythm changes, its cycle of the percussion accompaniment tend to change. The first case with deep structure is based on the tone repeated while the second case on susimga in free rhythm. The difference is in that a variety of syntactic structure is generated by the changing quality of the repeated deep structure in the former, whereas it is by the change from free to metric rhythm. The syntactic structure of jangdan rhythm comprises the deep structure or its equivalent idiomatic structure in a conclusive phrase in the first case, whereas it does not appear regularly in the second case. Characteristic features appeared in Pansori and Sanjo that are underlying in the deep structures can be shown by the fact that the surface structures transform into the deep structures or its transformational structure, and this means that the surface structure are constructed without fixed rules and implies relative characters of such musical genres which have no underlying deep structure.

본 연구에는 (삼마)태정탄광 산성광산배수(AMD)를 대상으로 수질 분석, 탈기 및 중화실험, 지구화학적 모델링을 수행하였다. 갱내수는 pH 3.34로 용존 Fe, Al, Mn, Mg, SiO2, CO2, SO4 2-이 고농도로 검출되었다. 주요 7종 성분의 농도에 대하여 화학양론적으로 물질량을 계산한 결과 침전물 발생량은 393 kg/d였으며, CO2, SO4 2-, Ca, Mg에 기인한 이차광물량이 오염물질량보다 컸다. 소석회중화반응 모델링에서 pH 6.5에서 방해석, pH 9 이상에서 Mn(OH)2, 수활석, 석고가 순차 침전되는것으로 예측되었다. 용존 CO2는 20분 동안의 탈기로 제거가 되어 방해석 침전을 제어할 수 있는 것으로 평가되었다. pH 9 이상에서 석고, 수활석의 침전이 슬러지 발생량 증대의 주요 원인으로 평가되었다. CO2 탈기 공정과 중화반응조 pH 9 이하 유지로 소석회 소비량 절감 및 침전물 최소화가 가능할 것으로 판단되었다.

Acid mine drainage from the (Samma)taejung coal mine was examined using water-quality analysis, degassing and neutralization trials, and geochemical modeling. The mine water was highly acidic (pH 3.34) and contained elevated levels of dissolved Fe, Al, Mn, Mg, SiO2, CO2, and SO4 2?. Stoichiometric calculations estimated approximately 393 kg/day of precipitation, with secondary minerals derived from CO2, SO4 2?, Ca, and Mg exceeding contaminant mass. Neutralization modeling showed that calcite precipitates around pH 6.5, while Mn(OH)2, brucite, and gypsum form sequentially above pH 9. Dissolved CO2 was removed within 20 min of degassing, which controlled calcite precipitation. At pH > 9, gypsum and brucite formation were identified as the main cause of sludge generation. These findings suggest that combining CO2 degassing with maintaining the neutralization reactor below pH 9 can reduce lime consumption and minimize sludge production.

익산 미륵사지 석탑은 백제 무왕대에 창건되어 몇 차례 수리 및 개축작업을 하면서 현 상태를 유지해 왔으나 최근에 구조적인 불균형이 심화되어 탑의 원형에 따른 보존과학적 수복을 위해 해체중이다. 이 탑의 원형은 평면방형탑으로 9층으로 추정되나 최근까지 일부 6층까지만 남아 있었다. 붕괴되어 망실된 부분은 1915년 일본인들이 콘크리트를 이용하여 불안전 탑의 형태를 고정시켜 놓았다. 현재 암석의 표면에는 침전물질이 피각되어 백화현상을 유발하였고 이로 인해 원암의 조직과 색상이 훼손되어 있다. 따라서 표면에 피각된 이차적 무기 오염물질의 종류와 산출상태 및 오염종을 정량 분석하였다. 또한 용해실험을 통해 가용성 오염종을 규명하고 이에 대한 오염물질을 세정하는데 필요한 조건을 제시하였다. 이 결과는 석조문화재 표면의 무기오염종을 정량적으로 규명할 수 있는 자료를 제공할 것이며, 백화현상을 제어 할 수 있는 표면 세정제의 보존과학적 적용에 기여할 것이다.

The Mireuksaji stone pagoda of the Iksan was built in Muwang King of Baekjae Kingdom and has maintained its present status through several rebuilding process. Recently, the structural unbalance of the pagoda has worsened, so for scientific maintenance recovery of its original pagoda form, the pagoda is under dismantling process. The original form of this pagoda is being presumed to be a plane square pagoda of nine stories, though only a portion of six stories remains until today. The destroyed part from collapse was liked in insecure pagoda form by Japanese in year of 1915. On the surface of the stone which has gone through the present time, efflorescence appeared as precipitation substance over crusted and due to this phenomenon, the structure and color of thee original stone haven't been preserved. Therefore, quantitative analysis on its kind, emitted status and contamination type of secondary inorganic contamination substance of the over crusted surface were analyzed. Also through reaction experiments, contamination type was defined and tests have been applied to find the requirements that will wash out the contaminants. The result of this study will provide the base of quantitative analysis on the kind of inorganic contamination of the surface of stone assets, and it shall also contribute to the application of scientific maintenance recovery of surface cleaner for efflorescence.

드론은 기존의 문화 콘텐츠와 다르게 실제 3차원 공간상에서 운동이 이루어지는 새로운 형태의 공연 소재이며 드론에 대한 대중의 관심도가 지속적으로 높아지고 있어 로보틱 아트의 새로운 콘텐츠로서 가능성을 가지고 있다. 최근 국내외적으로 드론을 활용한 많은 공연이 성공적으로 시도되고 있으며 관중들에게 새로운 감동을 주고 있다. 하지만, 작가가 아닌 기술엔지니어가 주도하고 있어 문화콘텐츠로서의 한계를 가지고 있으며 무엇보다도 공연은 상설이 아닌 이벤트성으로 진행되고 있다. 본 연구에서는 군집비행 제어기술을 활용한 드론공연에 대해 새로운 상설 문화 콘텐츠로서 실현될 수 있는 지에 대한 검증을 진행하였다. 드론 공연의 상설화 가능성을 검증하기 위해, 이번에 진행된 드론 공연은 드론의 실제 3차원 모션을 음악, 비디오와 동기화하여 구현되었다. 이를 통해 드론 공연이 관객에게 주는 예술적인 감동의 핵심은 공간 활용과 동기화임을 알 수 있었으며 현재의 공연 기술로는 관객의 감동을 증가하기 위한 작가의 의도를 충분히 반영하기에는 한계가 있음을 확인하였다. 또한 상설 공연을 위해서는 작가의 의도를 반영할 수 있는 스토리텔링 환경, 관객에게 피해를 주지 않는 공연시스템의 안정성, 그리고 항상 같은 결과를 만들어 낼 수 있는 재현성 등이 필수적임을 확인하였다. 선행 연구 결과를 반영한 새로운 공연시스템은 개발 단계부터 기술개발자와 공연 작가의 협업을 통해 진행 중이며, 무대 후면 외 무대 바닥면의 미디어 요소와 드론 운동과의 동기화를 진행 중이다. 새로운 로보틱 문화 콘텐츠로서 예술성을 확보하고 상설 공연을 진행할 목적으로 후속 연구를 진행 중이다.

The drone is a new type of performance object in which motion is performed in actual three-dimensional spaces, in contrast to existing performance content. Given that the popularity of drones is steadily increasing, drone performance factors are suitable as a new robotic content. Recently, numerous performances using drones have been successfully attained both in Korea and abroad, and new impressions have been disseminated to audiences. However, the performance capabilities of drones are limited as cultural content because most instances are driven by technical engineers and not by storytellers or writers, and drone performances are temporary events rather than any type of permanent performance. In this study, the feasibility of drone performance based on a formation flight control scheme as new permanent cultural content is discussed. To verify the possibility of permanent performances with drones, drone performances in the form of actual three-dimensional motions were synchronized with music and video. Through this type of drone performance, it was found that the core of artistic impression by the performance to the audience consists of space utilization and synchronization. However, the technical environments associated with drone performances are limited in their suitability for reflecting artists' intentions to increase the artistic impression. The most important aspects of drone performance are the storytelling environment which reflects the intention of the artist, the stability of the performance system so as not to harm the audience, and repeatability by which the performance can always be performed identically. The new performance system which reflects the results of previous research is being created through collaboration between technology developers, storytellers and writers in the development stage with synchronization of drone movements with media elements on the stage floor. Further studies are also underway on the topic of permanent performances to create artistic value as new robotic cultural content.

본 논문은 제2차세계대전 말기의 핵무기 개 발과 1960년대 핵통제 인식공동체 (epistemic community)가 형성되는 과정을 분석하는 것으 로서, 분석의 단초는 엠마누엘 아들러(Emanuel Adler)의 미국 중심적, 정책결정자 중심적 해석 이나 로렌스 위트너(Lawrence Wittner)의 평화 운동 중심적인 해석에 대한 문제제기이다. 과학 자의 기본임무는 연구결과의 이용을 예측하고 탐구하는데 있는 것이 아니라 과학의 내적 논리 와 합리성에 따라 아직 밝혀지지 않은 부분을 발견해 내는데 있다. 하지만 종전후 과학자들은 핵물리학의 전쟁 이용에 대한 도덕적 책임감과 함께 핵전쟁 회피를 위한 사명감을 느끼면서 핵 과학기술의 이용을 일부 통제하려고 하였다. 서 구의 과학자들뿐만 아니라 소련의 과학자들은 핵 및 미사일 기술의 급속한 발전을 보면서, 당 시 핵무기 증강에 의존하는 억지전략의 한계를 깨닫고 핵전쟁 회피가 양진영의 공통된 이익임 을 인식하기 시작했다. 초기 핵통제 아이디어는 이런 배경 속에서 나왔으며, 1957년부터 개최된 퍼그와쉬 회의(Pugwash Conferences)는 동서진 영의 과학자들(운동가로서, 연구자로서, 또는 자문가로서)이 교류하는 장이 되었으며 장차 초국가적 인식공동체를 형성하는 기반이 되었 다. 따라서 제한적 핵실험금지조약, SALT 협상, ABM 제한 조약 등 일련의 초기 핵통제 과정은 미국 주도만으로 이루어진 것이 아니었으며, 단 순히 반핵평화운동에 끌려간 결과인 것만도 아 니었다. 즉, 핵통제는 억지전략과 평화운동의 <접합>이었으며, 핵통제 연구는 전략연구와 평화학이 만나는 중간지점이었다. 그 주된 역할 은 과학자들에 의해 수행되었다.

This paper investigates the emergence of a transnational epistemic community of nuclear arms control in the 1960s. The analysis begins with a critical perspective on the two previous studies: One is Emanuel Adler’s U.S.-centered and elitist account of the emergence of an arms control epistemic community during the Cold War, and the other is Lawrence Wittner’s proposition of peace movement-driven arms control agreements. In general, scientists’ duty is to discover unidentified aspects of the nature, following scientific rationality and inner logic, rather than to investigate them after forecasting the utility of research outcomes. Scientists after World War Two, however, were keenly aware of a moral responsibility for the subordination of science to the atrocious war and thus tried to control, in part, the use of scientific knowledge and technological outcomes in order to avoid possibility of a nuclear war in the years of escalating East-West arms race. Alarmed by rapid developments of nuclear and missile technology, Western and Soviet scientists recognized limitations of their own existent nuclear deterrence strategy and considered avoidance of a nuclear war a common interest. The idea of nuclear arms control, at the initial stage, emerged in this context. The Pugwash Conference, which was held in 1957 for the first time, offered opportunities for the scientists in the East and the West to meet together and eventually build a “transnational” epistemic community in regards to the nuclear arms control. It is fair to say that the nuclear arms control in the early stage--as observed in the negotiations of the Limited Test Ban Treaty, Strategic Arms Limitation Treaty, and the Antiballistic Missile Treaty--was neither an outcome of U.S. initiatives nor a direct result of the antinuclear peace movements alone. The nuclear arms control was a kind of concession to the expanding peace movements, reflecting the limits of the existent nuclear deterrence. The studies on the nuclear arms control were situated between strategic studies and peace studies. Scientists are a major player on that important conjuncture, as either academics, or practitioners, or movement activists.

In this paper, we propose a formation control algorithm for underactuated autonomous underwater vehicles (AUVs) with parametric uncertainties using the approach angle. The approach angle is used to solve the underactuated problem for AUVs, and the leader-follower strategy is used for the formation control. The proposed controller considers the nonzero off-diagonal terms of the mass matrix of the AUV model and the associated parametric uncertainties. Using the state transformation, the mass matrix, which has nonzero off-diagonal terms, is transformed into a diagonal matrix to simplify designing the control. To deal with the parametric uncertainties of the AUV model, a self-recurrent wavelet neural network is used. The proposed formation controller is designed based on the dynamic surface control technique. Some simulation results are presented to demonstrate the performance of the proposed control method.

In this paper, the formation control problem is investigated for discrete-time multi-agent systems with unknown nonlinear dynamics by means of the iterative learning approach. For networks with switching topology, a distributed iterative learning scheme is developed using the local formation error data with anticipation in time, and a sufficient condition is derived to guarantee that the desired formation can be preserved during the whole finite-time motion or operation process, even in the presence of initial formation errors. Simulation results illustrate the effectiveness of the proposed method.

This paper proposes a sliding mode formation control method for electrically driven nonholonomic mobile robots in the presence of model uncertainties and disturbances. We use the kinematic model based on the leader-following approach for the formation control of multiple robots. Unlike many researches considering only the kinematic model, we also consider the dynamic model including actuator dynamics to obtain the voltage input because it is more realistic to use the voltage as input than the velocity. Then, the sliding mode control method is used to deal with model uncertainties and disturbances acting on the mobile robots. The stability of the proposed control system is proven using Lyapunov stability theory. Finally, we perform computer simulations to demonstrate the performance of the proposed control system.

This paper presents a control scheme for the leader-following formation of multiple robots. The control scheme combines the sliding mode control (SMC) method with the nonlinear disturbance observer (NDOB) technique. The formation dynamics suffer from uncertainties because the individual robots are uncertain. Concerning such formation uncertainties, the leader-following formation dynamics are modeled. Assuming that the formation uncertainties have an unknown boundary, an NDOB-based observer was designed to estimate the formation uncertainties. A sliding surface containing the observer outputs has been defined. Regarding the sliding surface, an SMC-based controller was investigated to form uncertain robots. A sufficient condition in the sense of the Lyapunov theory was proven such that the formation system is asymptotically stable. Herein, some comparison results between the sole SMC method and the second-order SMC method are presented to demonstrate the effectiveness and feasibility of the control scheme for multiple robots in the presence of uncertainties.

Motivated by the potentially application merits of wireless networked control systems (WNCSs), this paper presents a network-based formation framework for multi-agent systems. First, we construct a discrete formation protocol by integrating 802.11b. Meanwhile, one agent is considered as the reference, and the other ones keep a desired formation with the reference via communication networks. Using Lyapunov stability theory, sufficient convergence conditions are derived, and the verification problem of the sufficient conditions can be transformed as a linear matrix inequality (LMI) feasibility problem. Solving this LMI feasibility problem, a networked-based feedback controller can be easily obtained. Finally, simulation studies are provided to demonstrate the effectiveness of the proposed method.

In this paper, the leader-waypoint-follower formation is constructed based on relative motion states of nonholonomic mobile robots. Since the robots' velocities are constrained, we proposed a geometrical waypoint in cone method so that the follower robots move to their desired waypoints effectively. In order to form and maintain the formation of multi-robots, we combine stable tracking control method with receding horizon (RH) tracking control method. The stable tracking control method aims to make the robot's state errors stable and the RH tracking control method guarantees that the convergence of the state errors tends toward zero efficiently. Based on the methods mentioned above, the mobile robots formation can be maintained in any trajectory such as a straight line, a circle or a sinusoid. The simulation results based on the proposed approaches show each follower robot can move to its waypoint efficiently. To validate the proposed methods, we do the experiments with nonholonomic robots using only limited on-board sensor information.

The investigation of the formation of organic sulfur compounds (i.e., odor species), mainly methyl mercaptan and demethyl suifide, during kraft pulping has been conducted, in which both hardwood and softwood species were used. It was discovered that there is an organic sulfur compounds formation phase transition point with respect to delignification extent. The transition point occurs at a kappa number of approximately 35 and 20 for softwoods and hardwoods, respectively. The results also showed that both low sulfidity and anthraquinone (AQ) addition are helpful to control the formation of theses organic sulfur compounds during kraft pulping. Whereas Hexenuronic acid (HexA) has contribution to Kappa number, the extended delignification not only lead to low pulp yield, but also be adverse to odor control. A significant in-digester odor reduction can be achieved if the pulping is to be terminated before phase transition point and combined with AQ addition.

This paper addresses a decentralized observer-based output-feedback formation control problem for multiple unmanned underwater vehicles (UUVs). The complex nonlinear model for a UUV is feedback-linearized. It is assumed that each UUV in the formation exploits only the information regarding itself and the immediate predecessor, which imposes structural constraints on the formation controller gain matrices. The design condition is presented as a two-stage linear matrix inequalities problem. The synthesized controller demonstrates its own advantages through a numerical example.

This paper deals with the problem of steering a group of mobile robots along a reference path while maintaining a desired geometric formation. To solve this problem, the overall formation is decomposed into numerous geometric patterns composed of pairs of robots, and the state of the geometric patterns is defined. A control algorithm for the problem is proposed based on the Nash equilibrium strategies incorporating receding horizon control (RHC), also known as model predictive control (MPC). Each robot calculates a control input over a finite prediction horizon and transmits this control input to its neighbor. Considering the motion of the other robots in the prediction horizon, each robot calculates the optimal control strategy to achieve its goals: tracking a reference path and maintaining a desired formation. The performance of the proposed algorithm is validated using numerical simulations.

A modeling of vision based robot formation control system using fuzzy logic controller and extended Kalman filter is presented in this paper. The main problems affecting formation controls using fuzzy logic controller and vision based robots are: a robot's position in a formation need to be maintained, how to develop the membership function in order to obtain the optimal fuzzy system control that has the ability to do the formation control and the noise coming from camera process changes the position of references view. In order to handle these problems, we propose a fuzzy logic controller system equipped with a dynamic output membership function that controls the speed of the robot wheels to handle the maintenance position in formation. The output membership function changes over time based on changes in input at time t-1 to t. The noises appearing in image processing change the virtual target point positions are handled by Extended Kalman filter. The virtual target positions are established in order to define the formations. The virtual target point positions can be changed at any time in accordance with the desired formation. These algorithms have been validated through simulation. The simulations confirm that the follower robots reach their target point in a short time and are able to maintain their position in the formation although the noises change the target point positions.

In this paper, a formation control method based on the leader-following approach for nonholonomic mobile robots is proposed. In the previous works, it is assumed that the followers know the leader's velocity by means of communication. However, it is difficult that the followers correctly know the leader's velocity due to the contamination or delay of information. Thus, in this paper, an adaptive approach based on the parameter projection algorithm is proposed to estimate the leader's velocity. Moreover, the adaptive backstepping technique is used to compensate the effects of a dynamic model with the unknown time-invariant and time-varying parameters. From the Lyapunov stability theory, it is proved that the errors of the closed-loop system are uniformly ultimately bounded. Simulation results illustrate the effectiveness of the proposed control method.

This paper proposes a novel receding horizon control (RHC) algorithm for formation control of a swarm of unmanned surface vehicles (USVs) using particle swarm optimization (PSO). The proposed control algorithm provides the coordinated path tracking of multi-agent USVs while preventing collisions and considering external disturbances such as ocean currents. A three degrees-of-freedom kinematic model of the USV is used for the RHC with guaranteed stability and convergence by incorporating a sequential Monte Carlo (SMC)-based particle initialization. An ocean current model-based estimator is designed to compensate for the effect of ocean currents on the USVs. This method is compared with the PSO-based RHC algorithms to demonstrate the performance of the formation control and the collision avoidance in the presence of ocean currents through numerical simulations.

This paper studies the fault tolerant formation keeping problem of multi-agent systems with consideration of shortest connection topology. This is motivated by the requirement of low communication cost which largely depends on the communication length. Given a formation shape, a connection topology design method and its reconfiguration strategy are proposed in the sense that the whole connection path is shortest despite of communication faults. A control framework that combines the individual formation controller of each agent and connection topology is further presented. The stability of the whole system process is analyzed by switched system theories. Simulation results of unmanned aerial vehicles (UAVs) show the effectiveness of the proposed strategy.