• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.11
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• pp.1006-1012
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• 2007

In this paper, a suboptimal homing guidance law for the homing missiles with an impact angle constraint is presented. Unlike general LQ optimal control, the aided loop ensuring some degrees of freedom for the constraint is introduced. Then an optimal feedback loop in consideration of the aided loop is designed by using Schwartz inequality. The aided loop is synthesized with the optimal control to produce the guidance command. Furthermore, to investigate the characteristics of the guidance law we carry out the comparative studies with other guidance laws. The results of the various computer simulations show the good performance of the proposed law.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.7
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• pp.658-665
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• 2008

In this study a practical guidance law for missile guidance loop is established by considering the missile dynamics. Assuming the attitude controlled missile, several optimal guidance laws according to missile dynamical characteristics are derived by applying the optimal control theory and an effective guidance law in practical point is presented.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.217-218
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• 2007

최근 개발된 비선형 자동조종 제어기를 사용하면 비행 환경에 무관하게 BTT 미사일의 입출력 동특성이 일정한 선형 시스템의 형대로 표현될 수 있다. 본 논문에서는 이와 같은 특성을 바탕으로 BTT 미사일이 목표물의 취약 지점을 정밀하게 요격할 수 있도록 자동조종장치 동역학의 시간 지연 효과를 고려하여 표적 충돌각을 최소화하는 최적 종말 유도 법칙을 설계하였다. 제안된 최적 종말 유도 법칙은 극좌표 변환을 사용하지 않기 때문에 가제어성을 보장하며, 가속도 편향값을 사용하지 않기 때문에 기존의 유도 법칙에 비하여 미사일의 기동성을 향상시킬 수 있는 장점을 갖는다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.5
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• pp.412-418
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• 2007

An inverse optimal problem for homing guidance with angular constraint is addressed. The gains of BPN(Biased PN) are investigated by duality analysis related to the weighting matrices of the performance index in the LQ control problem. Moreover, the criteria for the existence of optimal gains are derived from the generalized Riccati equation. Based on the conditions we achieve the gain set of BPN to be optimal solution to the LQ problem with terminal constraints. To validate and demonstrate the proposed approach 3-DOF simulations are carried out.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.3
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• pp.203-211
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• 2016

In contrast with STT missiles, the guidance law design for BTT missiles should be based on 3-dimensional pursuit kinematics, since the pitch and roll channels of BTT missiles are coupled dynamically. More generally than the prior works, the dynamics of pitch and roll channels, as well as 3-dimensional pursuit kinematics are considered in the design of our terminal-phase optimal guidance law for BTT missiles proposed in this paper. Thereby, the proposed optimal guidance law guarantees high capturability with small miss distance without significant performance degradation due to time-lag effect even in case of relatively slow autopilot dynamics. Moreover, the resulting optimal guidance law is expressed explicitly in feedback-form with the coefficients given as the functions of time-to-go. The effectiveness and practicality of our work is demonstrated through various simulation results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.10
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• pp.998-1001
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• 2009

This paper shows that the conventional proportional navigation guidance(PNG) law with a constant navigation gain is an optimal solution strictly also when the velocity is varying during engagement. Especially, PNG with navigation constant, 3, is an optimal solution minimizing a closing velocity weighted induced-drag. While most of previous studies on optimality of PNG were relied on the linear formulation and the constant speed assumption, this study presents more general analysis results on optimality of PNG based on the nonlinear formulation and the time-varying velocity assumption.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.4
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• pp.367-371
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• 2009

Analysis on optimality of the proportional navigation guidance(PNG) law is presented in this paper. While most of previous studies on optimality of PNG were relied on the linear formulation, this paper is based on the nonlinear formulation. The analysis shows that PNG is an optimal solution minimizing a range-weighted control energy, where the weighting function is an inverse of $\alpha$ power of the distance-to-target. We show that the navigation constant N is related to $\alpha$ directly. And also the conditions required to ensure the analysis result are investigated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.884-890
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• 2008

A new guidance law to reach circular target area with grazing angle constraint is proposed as one of midcourse guidance laws of unmanned air vehicles. The purpose of the law is to control the grazing angle between the velocity vector of the vehicle and the line of sight to the aiming point, the center of the circular target area, when the vehicle passes any point on the circle. The optimal solution is derived based on the optimal control theory minimizing a range weighted control energy subject to the nonlinear dynamic equations of the vehicle approaching to the circular target area with grazing angle constraint. The major properties including a convergence of the solution are examined and the performance of the law applied to some typical scenarios is shown by the numerical simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.8
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• pp.669-676
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• 2015

In this paper, a guidance law for intercepting maneuvering target with a desired impact angle is proposed. The proposed guidance law is modified from the optimal impact angle control law for a fixed target and given by a biased PN law with the impact angle control term in addition to the conventional PN law. Three different kinds of desired impact angles in the respect of LOS angle, flight path angle, and relative flight path angle to the target are defined. The performance of the proposed guidance law is investigated via numerical simulations for various air-to-air engagement scenarios.

• ICROS
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• v.3 no.2
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• pp.26-33
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• 1997

본 논문에서는 위성발사체의 유조제어시스템에 대하여 일본의 발사체를 중심으로 개략적으로 살펴보았으며, 특히 최근 발사에 성공한 NASDA의 H-II 발사체의 SRB와 ISAS의 M-3SII의 상단의 조합으로 구성된 J-I 발사체의 유도제어시스템에 대하여 간략히 소개하였다. 또한, 발사체의 유도를 위한 여러 가지 유도법 가운데 일본의 과학위성 발사체 M-3H-3을 모델로 하여 최적제어이론을 이용한 발사체 유도법칙을 유도하였으며, 이 때 유도법칙의 해는 Newton-Raphson 수치해법 알고리즘을 사용하여 구하였다.