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Gaussian Mixture Approach to Decision Making for Automotive Collision Warning Systems
나원상,한슬기,황익호,박진배 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.5
This paper proposes a practical probabilistic approach to collision decision making which is necessary for advanced automotive collision warning system (CWS) using FMCW radar. Most decision making algorithms assess the probable collisions based on the predicted collision position which is usually expressed as a nonlinear function of threat vehicle’s position and velocity provided by FMCW radar. Since the predicted collision position has highly nonlinear statistics in general, it is one of main obstacles to improving the reliability of the collision probability computation and to developing real-time decision making algorithms. This motivates us to devise a Gaussian mixture method for collision probability calculation with the help of linear recursive time-to-collision (TTC) estimation. The suggested TTC estimator provides an accurate TTC estimate with small estimation error variance hence it enables us to approximate the probability density function of the predicted collision position as the weighted sum of just a few Gaussian distributions. Therefore, our approach could drastically reduce the inherent nonlinearity of collision decision making problem and computational complexity in collision probability calculation. Through the simulations for the typical engagement scenarios be-tween the host and threat vehicles, the performance and effectiveness of the proposed algorithm is compared to those of the existing ones which require heavy computational burden.
기동모델이 변침기동 탄도탄 추적에 미치는 영향에 대한 고찰
나원상,이찬석,정보영 대한전기학회 2022 전기학회논문지 Vol.71 No.12
This paper addresses the maneuvering ballistic target tracking problem for advanced missile defense systems. Based on the fact that the performance degradation of the existing tracking filters is mainly caused by the uncertainties in motion model of a ballistic target, an explicit maneuver model is introduced by utilizing a prior knowledge on the lift-induced drag characteristics. This model exploits the constraints among the ballistic coefficients, which enables us to design a tracking filter with more reliable target tracking performance in practice. Moreover, since the mismatch between our explicit ballistic target maneuver model and the real target motion leads to the bias of the residual sequence of the tracking filter, this property can also be used for target classification or recognition. Through simulation using a typical ballistic target tracking scenario, it is demonstrated that the proposed filter provides superior and reliable maneuvering ballistic target tracking performance.
나원상,황익호 제어로봇시스템학회 2008 제어로봇시스템학회 국내학술대회 논문집 Vol.2008 No.10
The closed-form solution of the linearized equation of motion of an unmanned aerial vehicle guided by the proportional navigation(PN) law is derived. While the existing results have been introduced for the lag-free system, the guidance loop with a first order missile dynamics is considered. It is shown that the proportional navigation trajectory can be expressed by the linear combination of confluent hypergeometric functions. Simulation results for the navigation constant n=3 demonstrate that the proposed analytic solution is an accurate estimate of the PN trajectory.
나원상,황익호 제어·로봇·시스템학회 2011 International Journal of Control, Automation, and Vol.9 No.5
A practical time-varying line-of-sight (LOS) rate estimator is proposed for surface-to-air missile (SAM) guidance using an RF seeker. The range-dependant LOS rate dynamics and variances of boresight error (BSE) measurements constitute the Kalman filtering problem associated with the time-varying matrix differential Riccati equation (DRE). Since the conventional gain-scheduled steady-state Kalman filter derived by solving an algebraic Riccati equation (ARE) cannot fully consider the time-varying nature of LOS rate dynamics, it might not be appropriate for volatile missile-target engage-ment scenarios. This motivates us to investigate a pseudo-analytic solution to the time-varying Kalman filtering problem based on the algebraic transform of the given DRE. Apart from the previous works, the explicit form of time-varying Kalman gain is expressed in terms of a single filter design parameter, called modified tracking index. The proposed time-varying filter is not only able to effectively handle the time-varying LOS rate dynamics but is also affordable for real-time implementation. Adjoint analysis results for a homing guidance loop show that the proposed LOS rate estimator could improve guidance performance and be an excellent choice for SAM applications.
Efficient Aimpoint Tracking using Target Range Profiles of a Wideband FMCW Seeker
나원상,황익호,신효상,Antonios Tsourdos 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.4
This paper proposes an efficient aimpoint tracking filter for high-range resolution FMCW radar seekers. A modified probabilistic data association scheme is devised to deal with closely located measurements generatedby scatterers of an extended target and multipath clutter. In order to discriminate the aimpoint measurement fromothers, an approximate target range profile is used for calculating likelihoods of the validated measurements. Simulationresults show the effectiveness and the superior performance of the proposed approach.
선배열 마이크를 이용한 강인 도래각 추정기법 및 인지로봇 청각시스템 응용
나원상(Won-Sang Ra),한슬기(Seul-Ki Ha),주영은(Young Eun Joo),김영하(Yeongha Kim),이혜경(Hye-Kyung Lee) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7
An efficient and practical DOA(direction of arrival) estimator using linear microphone array is proposed for developing cognitive robot ear. In the derivation of the acoustic signal measurement model for DOA estimation, the stochastic parameter uncertainty is inevitably included in the measurement matrix which causes the degradation of the estimation performance. As a remedy for this problem, the recently proposed robust least squares(RoLS) [1] can be used for DOA and frequency estimation. In spite of using the noisy measurement matrix, the estimation performance of the proposed scheme is by no means inferior to that of the optimal least squares-based method which cannot be realizable in actual situations. Simulation results show the superiority of the proposed method in estimation performance and computational efficiency.