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도심에서 수직구조물 랜드마크를 이용한 3D LIDAR 기반 차량정밀측위
임준혁(Jun-Hyuck Im),임성혁(Sung-Hyuck Im),송종화(Jong-Hwa Song),지규인(Gyu-In Jee) 제어로봇시스템학회 2017 제어·로봇·시스템학회 논문지 Vol.23 No.12
Tall buildings in urban areas obstruct the GPS satellite signal reception, thus the GPS position accuracy can be very poor. However, buildings in urban areas can be used to generate a landmark map for precise vehicle localization. This map’s information can be represented in various forms. We focused on the outer wall of a building that was erected vertically from the ground and almost flat. Therefore, vertical corners that meet the vertical planes are present everywhere in urban areas. These corners can provide very good landmarks and can be extracted using LIDAR. Additionally, traffic signs can be used for localization. The traffic signs are present in the road and reflect light well. Therefore, traffic signs can be clearly distinguished from other structures using LIDAR reflectivity. In this paper, we used building’s vertical corner and traffic signs for vehicle localization in an urban area. In addition, we proposed a vertical structure map with information for vertical corners and traffic signs. The experiment was carried out in the Gangnam area of Seoul, South Korea. The traveling distance was approximately 4.5 km and the maximum traveling speed was approximately 80 km/h. The lateral and longitudinal RMS position errors were 0.118 m and 0.231 m, respectively.
GNSS 수신기의 C-PRN 신호 기반 재방송재밍 완화기법
유승수(Seungsoo Yoo),염동진(Dong-Jin Yeom),지규인(Gyu-In Jee),김선용(Sun Yong Kim) 제어로봇시스템학회 2014 제어·로봇·시스템학회 논문지 Vol.20 No.10
In this paper, an effective repeat-back jamming (RBJ) mitigation scheme known assuccessive repeat-back jamming cancellation (SRC) is proposed for the utilization of the successive interference cancellation (SIC) algorithm which is used to mitigate the near-far effect and the multiple-access interference for code division multiple-access communication systems. The proposed scheme uses a combined pseudo-random noise (C-PRN) signal from the estimated major parameters of RBJ signals. To evaluate the performance of the proposed scheme, the root mean squared (RMS) code tracking errors are shown according to the standard deviation of the parameter estimation errors of an RBJ signal, and using the well-known major parameters estimation schemes with a C-PRN signal through Monte-Carlo simulation.
무인자동차의 경로점 주행 시 장애물 회피를 위한 경로생성 알고리즘
임준혁(Jun-Hyuck Im),유승환(Seung-Hwan You),지규인(Gyu-In Jee),이달호(Dal-Ho Lee) 제어로봇시스템학회 2011 제어·로봇·시스템학회 논문지 Vol.17 No.8
In this paper, an effective path generation algorithm for obstacle avoidance producing small amount of steering action as possible is proposed. The proposed path generation algorithm can reduce unnecessary steering because of the small lateral changes in generated waypoints when UGV (Unmanned Ground Vehicle) encounters obstacles during its waypoint navigation. To verify this, the proposed algorithm and A<SUP>*</SUP> algorithm are analyzed through the simulation. The proposed algorithm shows good performance in terms of lateral changes in the generated waypoint, steering changes of the vehicle while driving and execution speed of the algorithm. Especially, due to the fast execution speed of the algorithm, the obstacles that encounter suddenly in front of the vehicle within short range can be avoided. This algorithm consider the waypoint navigation only. Therefore, in certain situations, the algorithm may generate the wrong path. In this case, a general path generation algorithm like A<SUP>*</SUP> is used instead. However, these special cases happen very rare during the vehicle waypoint navigation, so the proposed algorithm can be applied to most of the waypoint navigation for the unmanned ground vehicle.
지능형 교통시스템에 적합한 위성항법 기반의 정밀측위 구조 설계
이병현(Byung-Hyun Lee),임성혁(Sung-Hyuck Im),허문범(Moon-Beom Heo),지규인(Gyu-In Jee) 제어로봇시스템학회 2012 제어·로봇·시스템학회 논문지 Vol.18 No.11
In this paper, a structure of precise positioning based on satellite navigation system is proposed. The proposed system is consisted with three parts, range domain filter, navigation filter and position domain filter. The range domain filter generates carrier phase-smoothed-Doppler and Doppler-smoothed-code measurements. And the navigation filter calculates position and velocity using double-differenced code/carrier phase/Doppler measurements. Finally, position domain filter smooth position error, and it means enhancement of positioning performance. The proposed positioning method is evaluated by trajectory analysis using precise map date. As a result, the position error occurred by multipath or cycle slip was reduced and the calculated trajectory was in true lane.
통합 의사잡음신호 기반 부호추적편이 추정에 따른 GPS L1 C/A 신호의 재방송재밍 영향 완화 기법
유승수(Seungsoo Yoo),염동진(Dong-Jin Yeom),지규인(Gyu-In Jee),김선용(Sun Yong Kim) 제어로봇시스템학회 2016 제어·로봇·시스템학회 논문지 Vol.22 No.10
In this paper, a novel scheme with which to mitigate a repeat-back jamming effect is proposed for the GPS L1 coarse/acquisition signal. The proposed scheme estimates the code tracking bias caused by repeat-back jamming signals using a Combined Pseudo-random noise signal. It then mitigates the repeat-back jamming effect by subtracting the estimated code timing on a normal correlation channel from the estimated value. Through a Monte-Carlo simulation, the proposed scheme can diminish the running average of code tracking bias to less than 10% of the bias using the conventional scheme.
임성혁(Sung-Hyuck Im),지규인(Gyu-In Jee) 제어로봇시스템학회 2009 제어·로봇·시스템학회 논문지 Vol.15 No.6
In this paper, an frequency tracking algorithm for weak signal tracking is proposed. The proposed frequency tracking algorithm uses a FMS (Fast Minus Slow) discriminator for frequency error estimation. This frequency tracking algorithm shows good frequency estimation performance under weak signal condition and is a computationally efficient for embedded software GNSS receiver. The software GNSS receiver implementing the proposed weak signal tracking algorithms could track GPS signal down to -159㏈m signal strength in the signal generator test and real GPS signal under dense urban condition.
실시간 GNSS 기만 시뮬레이터를 이용한 위성항법수신기에서의 기만 영향 분석
임성혁(Sung-Hyuck Im),임준혁(Jun-Hyuck Im),지규인(Gyu-In Jee),허문범(Mun-Beom Heo) 제어로봇시스템학회 2013 제어·로봇·시스템학회 논문지 Vol.19 No.2
In this paper, spoofing effects on a GNSS receiver were analyzed. The spoofer (spoofing device) was classified to two categories. One is an active spoofer and the other is a passive spoofer. The active spoofer was considered for analysis. For the analysis of spoofing effects on a GNSS receiver, a real-time GNSS spoofing simulator was developed. The simulator was consisted with two parts which are a baseband signal generation part and a RF up-conversion part. The first GNSS baseband signal was generated according to spoofing parameters such as range, range rate, GNSS navigation data, spoofing to GNSS signal ratio, and etc. The generated baseband signal was up-converted to GNSS L1 band. Then the signal transmitted to a GNSS signal. For a perfect spoofing, a spoofer knew an accurate position and velocity of a spoofing target. But, in real world, that is not nearly possible. Although uncertainty of position and velocity of the target was existed, the spoofer was operated as an efficient jammer.
LRF(Laser Range Finder) 거리와 반사도를 이용한 보행사 보호용 노면표시 검출기법 연구
임성혁(Sung-Hyuck Im),임준혁(Jun-Hyuck Im),유승환(Seung-Hwan Yoo),지규인(Gyu-In Jee) 제어로봇시스템학회 2012 제어·로봇·시스템학회 논문지 Vol.18 No.1
In this paper, a detection method of a pedestrian safety road marking was proposed. The proposed algorithm uses laser range and reflectivity of a range finder (LRF). For a detection of crosswalk marking and stop line, the DFT (Discrete Fourier Transform) of reflectivity and cross-correlation method between the reference replica and the measured reflectivity are used. A speed bump is detected through measuring an altitude difference of two LRFs which have the different tilted angle. Furthermore, we proposed a velocity constrained a detection method of a speed bump. Finally, the proposed methods are tested in on-line, on the pavement of a road. The considered road markings are wholly detected. The localization errors of both road markings are smaller than 0.4 meter.
GPS 교란 환경에서 벡터추적루프 기반 수신기 성능평가
송종화(Jong-Hwa Song),임성혁(Sung-Hyuck Im),지규인(Gyu-In Jee) 제어로봇시스템학회 2013 제어·로봇·시스템학회 논문지 Vol.19 No.2
In this paper, we represent the implementation and performance analysis of vector tracking loop based GPS receiver for jamming environment. The vector tracking loop navigation performance is compared by simulation with conventional tracking loop. The simulation results shows that vector tracking loop is more robust than conventional tracking loop in jamming environment. The vector tracking loop can gain 2dB in jamming performance capability over a conventional GPS receiver. Also, Anti-jamming performance of INS Doppler aiding and deep integration method are compared.