• 대한전기학회논문지:전력기술부문A
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• 제48권7호
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• pp.881-888
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• 1999

Target pointing guidance steers a vehicle to point at a target point at a given range Rs. In this paper, vehicle's motions relative to the target point are modeled by differential equations. Then a target pointing guidance law is derived using optimal control theories. In addition, it is shown that the proposed guidance law can achieve the goal of target pointing guidance whatever initial headings are.

• International Journal of Aeronautical and Space Sciences
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• 제15권2호
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• pp.163-172
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• 2014

This paper proposes a novel guidance law based on the block backstepping sliding mode control and extended state observer (ESO), which also takes into account the autopilot dynamic characteristics of the near space interceptor (NSI), and the impact angle constraint of attacking the maneuvering target. Based on the backstepping control approach, the target maneuvers and the parameter uncertainties of the autopilot are regarded as disturbances of the outer loop and inner loop, respectively. Then, the ESO is constructed to estimate the target acceleration and the inner loop disturbance, and the block backstepping sliding model guidance law is employed, based on the estimated disturbance value. Furthermore, in order to avoid the "explosion of complexity" problem, first-order low-pass filters are also introduced, to obtain differentiations of the virtual control variables. The stability of the closed-loop guidance system is also proven, based on the Lyapunov theory. Finally, simulation results demonstrate that the proposed guidance law can not only overcome the influence of the autopilot dynamic delay and target maneuvers, but also obtain a small miss distance.

• International Journal of Aeronautical and Space Sciences
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• 제8권1호
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• pp.46-53
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• 2007

In this paper, a guidance law for vision-based automatic landing of unmanned aerial vehicles (UAVs) is proposed. Automatic landing is a challenging but crucial capability for UAVs to achieve a fully autonomous flight. In an autonomous landing maneuver of UAVs, the decision of where to landing and the generation of guidance command to achieve a successful landing are very significant problem. This paper is focused on the design of guidance law applicable to automatic landing problem of fixed-wing UAV and rotary-wing UAV, simultaneously. The proposed guidance law generates acceleration command as a control input which derived from a specified time-to-go ($t_go$) polynomial function. The coefficient of $t_go$-polynomial function are determined to satisfy some terminal constraints. Nonlinear simulation results using a fixed-wing and rotary-wing UAV models are presented.

• 한국항공우주학회지
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• 제32권7호
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• pp.69-75
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• 2004

비행중인 다른 항공기를 회피하며 항공기를 목표점까지 유도하는 문제를 2차원 평면에서 고려하였다. 항공기는 속도의 크기가 일정한 질점이며, 제어입력으로 측가속도를 사용하는 것으로 가정하였다. 이동장애물에는 척력 포텐셜함수를 목적점에는 인력 포텐셜함수를 인공적으로 부여하여 항공기에 척력과 인력이 작용하도록 하였다. 유도/회피명령은 이들 포텐셜력과 상대속도를 사용하여 실시간으로 구현 가능한 유도/회피법칙을 구현하였다. Log 형태의 포텐셜함수를 사용하면 구현된 유도법칙은 잘 알려진 비례항법유도법칙이 되며, 회피법칙은 장애물까지 도달시간에 반비례하고 시선각 변화의 반대 방향으로 항공기를 회전시킨다. 제안된 유도/회피법칙은 시뮬레이션을 통하여 타당성을 검증하였다.

• 한국항공우주학회지
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• 제30권7호
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• pp.81-89
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• 2002

현재까지 개발된 다양한 형태의 유도법칙은, 유도개념에 따라 추적방식, 미사일과 표적에 의해 정의되는 방위각을 일정하게 유지시키는 유도법칙, 그리고 표적의 기동 예측에 기반한 유도법칙 등으로 분류할 수 있다. 본 논문에서는 이러한 개념적인 유도목적을 일반화한 유도법칙을 제안하였다. 제안한 유도법칙은 충돌삼각형 상에서 정의된 목표각을 사용하는데, 목표각은 매개변수의 설정에 따라 다양한 형태가 될 수 있다. 르야프노프 이론을 사용하여, 제안한 유도법칙은 목표각 오차의 반응이 1차 시스템과 동일함을 증명하였다. 그리고 자동조종장치의 동역학이 느릴 경우는, 목표각 오차 반응을 2차 시스템으로 모사할 수 있는 유도법칙도 제안하였다. 제안한 유도법칙의 유용성을 보이기 위하여 측정잡음을 포함한 시뮬레이션을 수행하고 결과를 제시하였다.

• International Journal of Aeronautical and Space Sciences
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• 제13권1호
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• pp.90-98
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• 2012

In this paper, the Integrated Guidance and Control (IGC) law is proposed for the Rotary Unmanned Aerial Vehicle (RUAV). The objective of the IGC law is to consider the nonlinear dynamic characteristics of the RUAV and to design a guidance law which takes into consideration the nonlinear relationship between kinematics and dynamics. In order to control the RUAV system, sliding mode control scheme is adopted. As the RUAV is an under-actuated system, a slack variable approach is used to generate the available control inputs. Through the Lyapunov stability theorem, the stability of the proposed IGC law is proved. In order to verify the performance of the IGC law, numerical simulations are performed for waypoint tracking missions.

• 한국해양공학회지
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• 제30권3호
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• pp.208-213
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• 2016

This paper proposes a potential field-based guidance law for docking a USV (unmanned surface vehicle). In most cases, a USV without side thrusters is an under-actuated system. Thus, there are undockable regions near docking stations where a USV cannot dock to a docking station without causing a collision or backward motion. This paper suggest a guidance law that prevents a USV from enter such a region by decreasing the lateral error to the docking station at the initial stage of the docking process. A Monte-carlo simulation was performed to validate the performance of the proposed method. The proposed method was compared to conventional guidance laws such as pure pursuit guidance and pure/lead pursuit guidance. As a result, the collision angle and lateral distance error of proposed method tended to have lower values compared to conventional methods.

• International Journal of Aeronautical and Space Sciences
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• 제18권4호
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• pp.719-728
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• 2017

This paper proposes a synthesis of new guidance law to generate an evasive maneuver against enemy's missile interception while considering its impact angle, acceleration, and field-of-view constraints. The first component of the synthesis is a new function of repulsive Artificial Potential Field to generate the evasive maneuver as a real-time dynamic obstacle avoidance. The terminal impact angle and terminal acceleration constraints compliance are based on Time-to-Go Polynomial Guidance as the second component. The last component is the Logarithmic Barrier Function to satisfy the field-of-view limitation constraint by compensating the excessive total acceleration command. These three components are synthesized into a new guidance law, which involves three design parameter gains. Parameter study and numerical simulations are delivered to demonstrate the performance of the proposed repulsive function and guidance law. Finally, the guidance law simulations effectively achieve the zero terminal miss distance, while satisfying an evasive maneuver against intercept missile, considering impact angle, acceleration, and field-of-view limitation constraints simultaneously.

• 한국군사과학기술학회지
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• 제5권1호
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• pp.96-106
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• 2002

Many modern guided weapon systems employ sophisticated target sensors as well as powerful computing systems. Due to such advanced features, they are required to achieve better guidance accuracy, and at the same time other guidance objectives for better weapon effectiveness and survivability. In this paper, we overview some of the technical considerations in such advanced guidance algorithm development, and briefly look at some related research works. More specifically, we discuss impact angle control, time-varying nature of the guidance system, time-to-go estimation, guidance loop stability, effect of autopilot lag and physical limitations in control variables, parasitic paths in guidance loops, etc. We also briefly look at some advanced concepts such as integrated guidance and control loop design, target adaptive guidance, guidance law development based on dual control concept, and terminal evasive maneuver.

• International Journal of Aeronautical and Space Sciences
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• 제4권2호
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• pp.26-36
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• 2003

The objective of this study is to enhance neural-network guidance to consider the impact condition. The optimal impact condition in this study is defined as an head-on attack. Missile impact-angle error, which is a measure of the degree to which the missile is not steering for a head-on attack, can also have an influence on the final miss distance. Therefore midcourse guidance is used to navigate the missile, reducing the deviation angle from head on, given some constraints on the missile g performance. A coordinate transformation is introduced to simplify the three-dimensional guidance law and, consequently, to reduce training data. Computer simulation results show that the neural-network guidance law with the coordinate transformation reduces impact-angle errors effectively.