• 항공우주시스템공학회지
• /
• 제1권3호
• /
• pp.37-42
• /
• 2007

The flight safety system for the satellite launch vehicles is required in order to minimize the risk due to launch vehicle failure. For prompt and reliable decision of flight termination, the flight safety system usually uses multiple sensors to estimate launch vehicle's flight trajectory. In that case, multiple types of observed tracking data makes it difficult to identify the flight termination condition. Therefore, a fusion tracking filter handling the multiple tracking data is necessary for the flight safety system. This research developed a simulation software for generating multiple types of launch vehicle tracking data, and then processed the data with fusion filters.

• 한국산업정보학회논문지
• /
• 제20권5호
• /
• pp.1-11
• /
• 2015

본 논문은 궤적데이터마이닝의 2차 회귀분석 기법을 이용하여 나로우주센터 내 원격자료수신장비에서 우주발사체의 실시간 비행궤적을 보다 정확하게 추정하기 위한 방법을 제시하고 있다. 원격자료수신장비는 추적손실 없이 실시간으로 우주발사체의 비행위치와 상태정보를 수신하기 위한 정확한 위치추정 알고리즘이 필요하다. 따라서 나로호 1차 발사 시, 기존 보간법에 의한 원격자료수신장비 안테나의 거친 구동특성을 보완하고 안정적인 발사체의 위치추정을 위한 2차 회귀기법을 고려하였다. 성능분석을 위해 나로호 1차 비행시험데이터를 사용하였고, 수학적 모델링을 통해 실시간 발사체의 비행위치정보를 추정한 결과가 분석되었다. 분석결과, 궤적데이터마이닝의 2차 회귀기법을 적용한 위치추정알고리즘이 기존의 보간법에 의한 위치추정알고리즘보다 향상된 안테나 구동특성 및 추정정확도를 보였다.

• 한국군사과학기술학회지
• /
• 제18권2호
• /
• pp.115-124
• /
• 2015

A methodology is proposed to estimate a trajectory of a flying target and its velocity using the time and frequency analysis of the acoustic signal. The measurement of sound emitted from a flying acoustic source with a microphone above a ground shall receive both direct and ground-reflected sound waves. For certain frequency contents, the destructive interference happens in received signal waveform reflected path lengths are in multiple integers of direct path length. This phenomenon is referred to as the acoustical mirror effect and it can be observed in a spectrogram plot. The spectrogram of acoustic measurement for a flying vehicle measurement shows several orders of destructive interference curves. The first or second order of curve is used to find the best approximate path by using nonlinear least-square method. Simulated acoustic signal is generated for the condition of known geometric of a sensor and a source in flight. The estimation based on cepstrogram analysis provides more accurate estimate than spectrogram.

• 한국항행학회논문지
• /
• 제12권4호
• /
• pp.295-303
• /
• 2008

고속으로 장거리를 비행하는 위성발사체는 고장 시 큰 위험을 줄 수 있으므로, 비행 궤도를 감시하고 고장여부를 판단하는 비행안전 시스템의 운용이 필수적이다. 비행안전 시스템에 적용되는 필터는 일반적인 위치추적 필터와는 달리 필터 정확성 보다는 신뢰성이 우선 시 되어야 하고, 정확한 순간낙하점 추정을 위해서는 궤도 위치뿐만 아니라 속도 역시 중요하게 여겨져야 한다. 본 논문에서는 KSLV-I 위성발사체 발사 시 운용되는 추적 센서를 적용하는 융합필터를 구성하고 궤도 및 순간낙하점을 계산하여 구성된 필터의 성능을 시험하였다.

• International Journal of Aeronautical and Space Sciences
• /
• 제18권3호
• /
• pp.512-521
• /
• 2017

This paper reports development process of a university-based sounding rocket using simplified hybrid rocket propulsion system for low-altitude flight application. A hybrid propulsion system was tried to be designed with as few components as possible for more economical, simpler and safer propulsion system, which is essential for the small scale sounding rocket operation as a CanSat carrier. Using blow-down feeding system and catalytic ignition as combustion starter, 250 N class hybrid rocket system was composed of three components: a composite tank, valves, and a thruster. With a composite tank filled with both hydrogen peroxide($H_2O_2$) as an oxidizer and nitrogen gas($N_2$) as a pressurant, the feeding pressure was operated in blowdown mode during thruster operation. The $MnO_2/Al_2O_3$ catalyst was fabricated for propellant decomposition, and ground test of propulsion system showed the almost theoretical temperature of decomposed $H_2O_2$ at the catalyst reactor, indicating sufficient catalyst efficiency for propellant decomposition. Auto-ignition of the high density polyethylene(HDPE) fuel grain successfully occurred by the decomposed $H_2O_2$ product without additional installation of any ignition devices. Performance test result was well matched with numerical internal ballistics conducted prior to the experimental propulsion system ground test. A sounding rocket using the developed hybrid rocket was designed, fabricated, flight simulated and launch tested. Six degree-of-freedom trajectory estimation code was developed and the comparison result between expected and experimental trajectory validated the accuracy of the developed trajectory estimation code. The fabricated sounding rocket was successfully launched showing the effectiveness of the simplified hybrid rocket propulsion system.

• 한국군사과학기술학회지
• /
• 제11권3호
• /
• pp.5-12
• /
• 2008

This paper presents the features of an impact angle constrained open-loop optimal trajectory which is given by a function of initial conditions and optimal guidance gains. Using missile motion described by linearized kinematic equations and a proper form of performance index, an inverse optimal problem is suggested to investigate the gains related to the performance index. The flight trajectory and time-to-go can be shaped in terms of the optimal guidance gains. The results are evaluated by 3-DOF simulation.

• 한국항공우주학회지
• /
• 제46권5호
• /
• pp.385-392
• /
• 2018

본 논문은 플라잉디스크에 탑재된 계측모듈의 IMU 데이터를 이용하여 롤링 및 피칭모멘트 감쇠미계수를 추정하는 방식을 새롭게 제시한다. 제안한 방식은 반복된 수 회의 원반 비행 실험을 수행하여 데이터를 구축한 뒤 공력 계수를 추정하므로, 풍동이나 전산유체해석을 이용하는 방법에 비해 수월한 실험적 대안이 될 수 있다. 추정한 공력 계수는 플라잉디스크의 비행동역학 모델을 토대로 구현한 시뮬레이터에 적용하여 비행 궤적을 예측하는 것에 이용되었으며, 이를 GPS의 위치 궤적과 비교함으로써 성능을 검증하였다.

• 전자통신동향분석
• /
• 제36권2호
• /
• pp.1-11
• /
• 2021

As sensors such as Inertial Measurement Unit, cameras, and Light Detection and Rangings have become cheaper and smaller, research has been actively conducted to implement functions automating micro aerial vehicles such as multirotor type drones. This would fully enable the autonomous flight of drones in the real world without human intervention. In this article, we present a survey of state-of-the-art development on autonomous drones. To build an autonomous drone, the essential components can be classified into pose estimation, environmental perception, and obstacle-free trajectory generation. To describe the trend, we selected three leading research groups-University of Pennsylvania, ETH Zurich, and Carnegie Mellon University-which have demonstrated impressive experiment results on automating drones using their estimation, perception, and trajectory generation techniques. For each group, we summarize the core of their algorithm and describe how they implemented those in such small-sized drones. Finally, we present our up to date research status on developing an autonomous drone.

• 한국항공우주학회지
• /
• 제38권10호
• /
• pp.1012-1019
• /
• 2010

본 논문에서는 다중표적 비행시험을 위한 비행 자료처리 시스템이 설계되었다. 비행자료 처리를 위해 표적그룹 처리, 자료융합 처리 및 자료연동 처리가 수행 되었으며, 자료융합 필터로서 집중형 칼만필터와 연합형 칼만필터를 설계하였다. 특히 집중형 필터에 레이더의 SNR과 추정기법을 적용하여 비행체의 저고도 계측을 개선하였다. 개발된 시스템을 다중표적 비행시험에 적용한 결과, 저고도 및 초기구간에서 개선된 비행궤적을 확인할 수 있었다.

• 한국군사과학기술학회지
• /
• 제18권3호
• /
• pp.234-243
• /
• 2015

It is required to have the capability to predict the impact point of the ballistic target in order to assign the firing unit with high engagement possibility for the interception in the ballistic target defense systems. In this paper, a novel method is proposed to predict the impact point of the ballistic target using a flight phase discrimination algorithm given the insufficient measurements on the partial trajectory. The flight of a ballistic target is composed of a boost phase and a ballistic phase with different dynamics. The flight phase is discriminated by using the normalized innovation distance between measurements and a priori estimated measurements. The threshold and tolerance in the flight phase discrimination are determined from the probabilistic characteristics of the estimation error. Monte Carlo simulations are performed to verify the proposed method.