• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.463-467
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• 2005

In this paper, the guidance law applicable to formation flight of UAV in three-dimensional space is proposed. The concept of miss distance, which is commonly used in the missile guidance laws, and Lyapunov stability theorem are effectively combined to obtain the guidance commands of the wingmen. The propose guidance law is easily integrated into the existing flight control system because the guidance commands are given in terms of velocity, flight path angle and heading angle to form the prescribed formation. In this guidance law, communication is required between the leader and the wingmen to achieve autonomous formation. The wingmen are only required the current position and velocity information of the leader vehicle. The performance of the proposed guidance law is evaluated using the complete nonlinear 6-DOF aircraft system. This system is integrated with nonlinear aerodynamic and engine characteristics, actuator servo limitations for control surfaces, various stability and control augmentation system, and autopilots. From the nonlinear simulation results, the new guidance law for formation flight shows that the vehicles involved in formation flight are perfectly formed the prescribed formation satisfying the several constraints such as final velocity, flight path angle, and heading angle.

• International Journal of Aeronautical and Space Sciences
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• 제10권1호
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• pp.30-36
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• 2009

Many formation guidance laws have been proposed for VAV formation flight. Since most autonomous formation flight methods require various active communication links between the vehicles to know motion information of other vehicles, damage to the receiver or the transmitter and communication delay are critical problem to achieve a given formation flight mission. Therefore, in this point of view, the method that does not need an inter-vehicle communication is preferred in the autonomous formation flight. In this paper, we first summarize the formation guidance law without an inter-vehicle communication using feedback linearization and sliding mode control proposed in previous study. We also propose the modified formation guidance law with robust disturbance observer, which can provide significantly better performance than previously mentioned guidance law in case that other vehicles maneuver with large accelerations. The robust disturbance observer can estimate uncertainties generated by acceleration of leader vehicle. By eliminating the uncertainties using the estimated uncertainties, VAVs are able to achieve the tight formation flight. The performance of the proposed approach is validated by numerical simulations.

• International Journal of Aeronautical and Space Sciences
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• 제12권1호
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• pp.16-23
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• 2011

In this paper, nonlinear model predictive control (NMPC) is addressed to develop formation guidance for multiple unmanned aerial vehicles. An NMPC algorithm predicts the behavior of a system over a receding time horizon, and the NMPC generates the optimal control commands for the horizon. The first input command is, then, applied to the system and this procedure repeats at each time step. The input constraint and state constraint for formation flight and inter-collision avoidance are considered in the proposed NMPC framework. The performance of NMPC for formation guidance critically degrades when there exists a communication failure. In order to address this problem, the modified optimal guidance law using only line-of-sight, relative distance, and own motion information is presented. If this information can be measured or estimated, the proposed formation guidance is sustainable with the communication failure. The performance of this approach is validated by numerical simulations.

• 한국항공우주학회지
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• 제36권9호
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• pp.859-866
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• 2008

본 논문에서는 다수 비행체의 편대 비행 시 상호 기하학적 관계 유지에 필요한 유도 법칙과 비선형 시뮬레이션 결과를 제시하였다. 편대 내의 각 비행체는 편대 Leader를 제외하고 모두 Leader와 Follower의 역할을 동시에 맡으며, Leader에 의한 명령은 모든 Follower에게 분배되고 따라서 편대를 이루는 모든 비행체들의 동시기동비행(Synchronized Flight)을 가능하게 한다. 편대 비행 유도 법칙은 가까운 미래 시각에 예상되는 기하학적 오차 그리고 Lyapunov 안정성 이론에 근거하여 도출하였고, 정찰과 감시 임무 예제에 관한 고정밀 비선형 시뮬레이션 결과를 통하여 제안된 유도 법칙의 성능을 검증하였다

• 제어로봇시스템학회논문지
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• 제18권2호
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• pp.87-93
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• 2012

In this paper, a formation guidance method for UAVs (Unmanned Aerial Vehicles) to simulate the formation flight of birds proposed. The proposed method solves all issues of approaching for formation, formation keeping, and scarce chance to be collided with each UAV during formation process. Also, we design the feedforward controller to compensate the change of speed and heading for maneuvering of the leader UAV and the feedback controller to consider the response lag of the system. The stability and performance of the proposed controller is verified via numerical simulations of the full 6-Dof model of UAV.

• International Journal of Aeronautical and Space Sciences
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• 제14권1호
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• pp.75-84
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• 2013

In this paper, the guidance law for formation flight and collision avoidance of multiple Unmanned Aerial Vehicle (UAV)s is proposed. To construct the physically comprehensible guidance law for formation flight, the virtual structure approach is used. To develop a guidance law for collision avoidance considering both other UAVs and unknown static obstacles, a geometric approach using information such as a relative position vector is utilized. Through the Lyapunov theorem, the stability of the proposed guidance law is proved. To combine guidance commands, the concept of the elastic weighting factor inspired by the elastic behavior of shape memory polymer, which tends to regain its original shape after deformation, is introduced. By using the concept of elastic weighting factor, multiple UAVs are able to cope actively with the situation of a collision between both UAVs and static obstacles during the formation flight. To verify the performance of the proposed method, numerical simulations are performed.

• 제어로봇시스템학회논문지
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• 제20권12호
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• pp.1217-1224
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• 2014

This paper presents a modified track guidance algorithm for formation flight of multiple UAVs. The suggested guidance algorithm is the spatial version of the first order dynamic characteristics for a time-dependent system so the algorithm is able to generate a path without overshoot to track the desired line. A crucial design parameter is a spatial constant that controls the shape of the convergence to an assigned flight path similarly to a time constant. Reference flight trajectories are designed based on a two-dimensional vehicle model, and the performance of the proposed guidance law is verified by numerical simulation using rigid body UAV dynamics with MATLAB/Simulink Aerosim Blockset.

• 한국항공우주학회지
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• 제39권2호
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• pp.121-127
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• 2011

본 논문에서는 초소형 비행체의 자동 편대 비행을 위한 유도 법칙과 비행 시험 결과를 기술하였다. 초소형 비행체는 탑재 중량과 비행시간 등의 제한으로 인해 짧은 시간 안에 복수의 비행체가 임무를 분담하거나 협력하여 동시에 수행하는 것이 효율적이며 편대 비행은 이러한 임무 하중을 효과적으로 감소시킬 수 있다. 제안된 편대 유도 법칙은 Leader-Follower 편대 비행의 기하학적 관계 기반으로 비선형 모델 역변환 기법을 이용하여 설계하였다. 편대 유도 법칙에 필요한 비행체의 상태 정보는 비행체 간 고속의 데이터 통신 시스템을 구성하고 지상국을 통해 송수신하도록 하였다. 본 연구에서 제안된 비행체간 통신 기반의 편대 유도 기법은 센서의 측정 잡음에 대한 강건한 성능을 확인하기 위해 실제 비행 데이터 기반 시뮬레이션을 수행하였고 다수의 초소형 비행체를 이용한 편대 비행 시험을 통해 유도 법칙의 타당성을 검증하고 확인하였다.

• 제어로봇시스템학회논문지
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• 제15권1호
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• pp.8-14
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• 2009

A formation flight guidance logic that enables the leader-follower station keeping between two UAVs is presented in this paper. The logic is motivated by the investigation of the relation between the proportional navigation and the nonlinear trajectory tracking guidance law, The simplicity of the presented method provides computational efficiency and allows easy implementation. An excellent performance of the proposed logic is demonstrated via various numerical simulations for multiple UAVs environment.

• 한국항공우주학회지
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• 제38권3호
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• pp.264-273
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• 2010

본 연구에서는 무인항공기의 편대비행을 위해서 먼저 단일 무인항공기의 기본적인 자세제어, 고도제어를 포함하는 유도제어시스템을 설계 제작하여 검증하고, 이 시스템을 바탕으로 먼저 선도기의 위치 정보를 이용하여 선도기와 추종기간의 앞뒤거리와 좌우 거리를 피드백하여 비례미분제어한 결과를 보여준다. 보다 안정적이고 성능이 우수한 편대 비행을 위하여 선도기의 위치와 자세 정보를 이용하여 추종기가 따라가야할 가상경로점을 실시간으로 계산하고 이를 바탕으로하여 추종기가 따라가도록 유도 명령을 생성하여 비행제어를 하고, 또한 선도기의 롤명령정보를 추종기의 최종 유도명령에 추가하여 편대 비행 성능을 향상시킬 수 있음을 보여준다. 이러한 과정은 여러 가지 경우에 대한 비행시험 결과를 분석하여 알고리즘을 점차 개선하는 방식을 취했으며 다소 실험적인 방식으로 최종 편대비행 알고리즘을 확립하였다. 최종적으로 채택한 기법을 이용하여 3대의 무인항 공기를 자동비행 상태에서 편대 비행을 수행한 결과를 보여준다.