터널 내 소화기 표시등 검출을 이용한 3D LIDAR 기반 차량정밀측위

임준혁(Jun-Hyuck Im),임성혁(Sung-Hyuck Im),지규인(Gyu-In Jee) 제어로봇시스템학회 2018 제어·로봇·시스템학회 논문지 Vol.24 No.8

Vehicle localization is essential for autonomous driving. Basically, the position information of the autonomous vehicle is obtained from the Global Positioning System (GPS). More accurate localization can be performed by using maps and various sensors that are mounted on the autonomous vehicle. GPS receivers cannot receive GPS signals in tunnels, so dead reckoning (DR) is used for vehicle localization. However, the error from DR continuously accumulates. Therefore, this error must be corrected by using vehicle-mounted sensors, such as Light Detection and Ranging (LIDAR) and cameras. Tunnels have very specific shape information, which is usually an ellipse, and several emergency facilities exist in tunnels. Some facilities are separated from the tunnel wall, which can be detected by using 3D LIDAR. In particular, fire extinguisher lamps are periodically installed at intervals of 50 m, which can serve as good landmarks. First, the point cloud for the tunnel wall must be removed to effectively detect fire extinguisher lamps. This process can be easily conducted by using shape information. After this removal, we detect the fire extinguisher lamps. In this paper, we propose a 3D LIDAR-based vehicle-localization method that uses ellipse parameters and fire extinguisher lamps in road tunnels. These experiments are conducted at the Maseong tunnel in South Korea. The experimental results show that the root mean square (RMS) position errors in the lateral and longitudinal directions were 0.06 m and 0.23 m, respectively, exhibiting precise localization accuracy.

소프트웨어 기반 Loran-C 신호 처리

임준혁(Jun-Hyuck Im),임성혁(Sung-Hyuck Im),김우현(Woo-Hyun Kim),지규인(Gyu-In Jee) 제어로봇시스템학회 2010 제어·로봇·시스템학회 논문지 Vol.16 No.2

With GPS being the primary navigation system, Loran use is in steep decline. However, according to the final report of vulnerability assessment of the transportation infrastructure relying on the global positioning system prepared by the John A. Volpe National Transportation Systems Center, there are current attempts to enhance and re-popularize Loran as a GPS backup system through the characteristic of the ground based low frequency navigation system. To advance the Loran system such as Loran-C modernization and eLoran development, research is definitely needed in the field of Loran-C receiver signal processing as well as Loran-C signal design and the technology of a receiver. We have developed a set of Matlab tools, which implement a software Loran-C receiver that performs the receiver’s position determination through the following procedure. The procedure consists of receiving the Loran-C signal, cycle selection, calculation of the TDOA and range, and receiver’s position determination through the Least Square Method. We experiences the effect of an incorrect cycle selection and various error factors (ECD, ASF, sky wave, CRI, etc.) from the result of the Loran-C signal processing. It is apparent that researches which focus on the elimination and mitigation of various error factors need to be investigated on a software Loran-C receiver. These aspects will be explored in further work through the method such as PLL and Kalman filtering.

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.

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.

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.

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.

신호등을 이용한 영상 기반 차량 측위

이수정(Su Jung Lee),임준혁(Jun Hyuck Im),지규인(Gyu In Jee) 제어로봇시스템학회 2017 제어·로봇·시스템학회 논문지 Vol.23 No.7

Recently, the precise vehicle localization matching precision map and localization methods based on multiple sensors were studied. Vision sensors are easy to use and mount on most vehicles because of their low price. The vehicle localization using vision sensors commonly uses landmarks such as road marks or transport facilities to recognize the lateral position of the vehicle, but localization using road marks is affected by vehicles on the road. Meanwhile, because traffic lights, which are installed at high places of the roads, can always be detected despite heavy traffic, they secure the visibility. This paper estimates the position of a vehicle using landmark map, which includes three-dimension traffic light positions. The horizontal and vertical angles between the traffic light and the vehicle are used to estimate the lateral and longitudinal errors of vehicle, respectively. Using the vertical angle improves the estimation performance of the longitudinal error of the vehicle. The experiments were performed on an urban road. The lateral and longitudinal errors of the vehicle decreased by approximately 50 cm and 80 cm respectively.

도로 노면 정보를 이용한 그래프 기반 자율주행용 정밀지도 생성

조성준(Sung-Joon Cho),임준혁(Jun-Hyuck Im),지규인(Gyu-In Jee) 제어로봇시스템학회 2016 제어·로봇·시스템학회 논문지 Vol.22 No.12

As location recognition for autonomous vehicles develops, the need for a precise map for autonomous driving has increased. A precise map must be built based upon accurate position. Recent studies have accelerated research in this area by using various sensors that calculate the accurate position by comparing and recognizing objects around the roads. However, application of such methods is limited because these studies only take objects with significant verticality into consideration. Thus, new research is needed to overcome the limitations: a method that is not constrained by the existence of certain types of surrounding objects shall be proposed. Most roads contain road marking information, such as lanes, direction signs, and pedestrian crossings. Such information on the road surface is a valuable resource for building a precise map. This paper proposes a method of building a precise map by using road marking information.

GPS L1 C/A 코드 신호의 신호추적 및 항법기만 가능성 분석

이병현(Byung Hyun Lee),임준혁(Jun-Hyuck Im),임성혁(Sung-Hyuck Im),지규인(Gyu-In Jee),양진모(Jin Mo Yang),이민준(Min Joon Lee) 한국통신학회 2011 한국통신학회 학술대회논문집 Vol.2011 No.6

기만(spoofing)신호는 원래 신호와 동일하거나 또는 유사한 신호를 만들어 원래 신호의 이용을 방해 또는 기만신호를 이용하여 잘못된 결과를 도출하게 만드는 목적을 갖는다. 따라서 유도무기에서 많이 사용되는 GPS 수신기가 이러한 기만신호에 의해서 잘못된 항법해를 도출하여 유도무기의 항법기능을 무력화 시킬 수 있는 가능성에 대해서 거론되고 있다. 본 논문에서는 GPS 수신기가 기만신호에 의해서 기만될 수 있는 가능성에 대해서 신호추적 및 항법기만 실험을 통하여 확인하였다. 실험을 위해서 GPS 신호와 기만신호를 생성하는 RF 레벨의 GPS/기만신호 발생장치를 개발하였다. 개발된 발생장치는 GPS+Spoofing 신호를 생성하여 National Instrument 사의 RF 신호 발생기를 통하여 L1 대역으로 생성하여 수신기의 안테나 입력에 신호를 인가할 수 있도록 제작되었다. 실험결과 상용 GPS 수신기(Novatel OEMV3/OEM-V1, Ublox 등)에 기만신호를 인가하여 완전히 기만될 수 있음을 확인하였다. 하지만 기만되는 상황을 만들기 위해서는 많은 제약조건이 존재하며, 제약조건의 변화에 따른 영향을 분석하여 제시하였다.

무인자동차의 모델 예측제어를 위한 장애물 파라미터 모델링 기법

여정윤(Jung-Yun Yeu),김우현(Woo-Hyun Kim),임준혁(Jun-Hyuck Im),이달호(Dal-Ho Lee),지규인(Gyu-In Jee) 제어로봇시스템학회 2012 제어·로봇·시스템학회 논문지 Vol.18 No.12

The MPC (Model Predictive Control) is one of the techniques that can be used to control an unmanned vehicle. It predicts the future vehicle trajectory using the dynamic characteristic of the vehicle and generate the control value to track the reference path. If some obstacles are detected on the reference paths, the MPC can generate control value to avoid the obstacles imposing the inequality constraints on the MPC cost function. In this paper, we propose an obstacle modeling algorithm for MPC with inequality constraints for obstacle avoidance and a method to set selective constraint on the MPC for stable obstacle avoidance. Simulations with the field test data show successful obstacle avoidance and way point tracking performance.