레이저스캐너를 이용한 차량저속운전보조장치의 설계

문희창(Hee Chang Moon),손영진(Young Jin Son),김정하(Jung Ha Kim) 제어로봇시스템학회 2008 제어·로봇·시스템학회 논문지 Vol.14 No.8

This paper describes a vehicle low speed driving assistant (VLDA) system that is composed of laser scanner. This vehicle is designed for following lead vehicle (LV) without driver’s operation. The system is made up several component systems that are based on unmanned ground vehicle (UGV). Each component system is applied to use advanced safety vehicle developed to complete UGV system. VLDA system was divided into vehicle control system and obstacle detecting system. The obstacle detecting system calculate distance and angle of LV and transmit these data to vehicle control system using front, left and right laser scanners. Vehicle control system makes vehicle control values such as steering angle, acceleration and brake position and control vehicle’s movement with steering, acceleration and brake actuators. In this research, we designed VLDA system like as low speed cruise control system and test it on real road environments.

Longitudinal static stability requirements for wing in ground effect vehicle

Yang, Wei,Yang, Zhigang,Collu, Maurizio The Society of Naval Architects of Korea 2015 International Journal of Naval Architecture and Oc Vol.7 No.2

The issue of the longitudinal stability of a WIG vehicle has been a very critical design factor since the first experimental WIG vehicle has been built. A series of studies had been performed and focused on the longitudinal stability analysis. However, most studies focused on the longitudinal stability of WIG vehicle in cruise phase, and less is available on the longitudinal static stability requirement of WIG vehicle when hydrodynamics are considered: WIG vehicle usually take off from water. The present work focuses on stability requirement for longitudinal motion from taking off to landing. The model of dynamics for a WIG vehicle was developed taking into account the aerodynamic, hydrostatic and hydrodynamic forces, and then was analyzed. Following with the longitudinal static stability analysis, effect of hydrofoil was discussed. Locations of CG, aerodynamic center in pitch, aerodynamic center in height and hydrodynamic center in heave were illustrated for a stabilized WIG vehicle. The present work will further improve the longitudinal static stability theory for WIG vehicle.

접지방식에 따른 철도차량의 접지고장 특성 비교

임형순(Hyeong-Sun Lim),김연준(Yeon-Jun Kim),최진(Jin Choi),이병석(Byung Suk Lee) 한국철도학회 2016 한국철도학회 학술발표대회논문집 Vol.2016 No.10

철도차량에서 발생될 수 있는 접지 고장은 전차선의 지락에 의한 고장, 낙뢰, 고압회로의 단락, 접지 등이 있다. 접지고장이 발생되면 고전압 및 고장전류에 의해 전기적인 충격으로부터 사람의 사상 및 기기의 고장이 발생될 수 있다. 이들로부터 인명 및 기기를 보호하기 위해서 접지 회로를 구성한다. 본 논문에서는 국제전기표준회의(International Electro-technical Commission : IEC)에서 정의된 접지방식과 고속차량에 적용된 접지방식에 대해서 검토하였다. 또한 접지저항과 고장형태에 따른 고장루프 및 감전 경로를 바탕으로 전기적인 등가회로를 구성하였다. 제안한 등가회로를 기준으로 모델링을 수행하여 접지방식에 의한 접지 전류, 접촉전압과 감전전류를 비교하여 고속차량에 적용된 접지회로의 타당성을 확인하였다. The high voltage circuit and the circuit configuration of a railway vehicle is a rule that can shortcircuit and ground fault protection, lightning, catenary earth fault. If ground fault occurs the electrical shock is generated by the high voltage and fault current. This is the cause of a person’s risks and mechanical breakdown. Typically constitutes a ground circuit to protect human life and equipment. This paper is compared with IEC ground system and ground system that have been applied for rolling stock. In addition, this was reviewed earth resistance, fault current in accordance with the contemporary electric shock. Based on this, a simulation was carried out with an equivalent circuit. It was confirmed the validity of the ground circuit applied to a railway vehicle.

Longitudinal static stability requirements for wing in ground effect vehicle

Wei Yang,Zhigang Yang,Maurizio Collu 대한조선학회 2015 International Journal of Naval Architecture and Oc Vol.7 No.2

The issue of the longitudinal stability of a WIG vehicle has been a very critical design factor since the first experimental WIG vehicle has been built. A series of studies had been performed and focused on the longitudinal stability analysis. However, most studies focused on the longitudinal stability of WIG vehicle in cruise phase, and less is available on the longitudinal static stability requirement of WIG vehicle when hydrodynamics are considered: WIG vehicle usually take off from water. The present work focuses on stability requirement for longitudinal motion from taking off to landing. The model of dynamics for a WIG vehicle was developed taking into account the aerodynamic, hydrostatic and hydrodynamic forces, and then was analyzed. Following with the longitudinal static stability analysis, effect of hydrofoil was discussed. Locations of CG, aerodynamic center in pitch, aerodynamic center in height and hydrodynamic center in heave were illustrated for a stabilized WIG vehicle. The present work will further improve the longitudinal static stability theory for WIG vehicle.

무인 항공기의 영상 기반 지상 목표물 인식 기법

백광열,전병일,방효충 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.4

본 논문은 무인항공기의 항공영상 내의 지상 목표물을 인식하는 영상처리 기법과 구현 결과를 논한다. 지상 목표물 후보를 인식하기 위해 Haar-like 특징과 거절 케스케이드 형태의 분류구조를 갖는 Viola-Jones 분류기를 적용하였다. 위성지도 영상으로부터 지상 차량에 대한 다수의 참 영상을 획득하고 다수의 거짓 영상을 이용하여 분류기를 학습시켰다. 위성지도 영상과 다수의 항공 영상을 이용한 모의 실험을 통해 인식 성능을 검증하였다. 또한 실제 비행 실험을 통해 획득한 무인항공기 촬영 영상에 대해 지상 목표물 인식 할 수 있음을 확인하였다. This paper addresses ground vehicle detection algorithm on aerial image from an unmanned aerial vehicle. We utilize Viola-Jones classifier to detect ground vehicle on aerial image. The Viola-Jones classifier has a cascade structure of boosted classifier applying Haar-like features. The classifier for ground vehicle is trained using a set of positive object images sampled from satellite map images and a set of negative background images. The trained classifier is verified by satellite images and various aerial images. We demonstrate the performance of ground vehicle detection algorithm on aerial images from flight tests

DESIGN AND DEVELOPMENT OF A HEADING ANGLE CONTROLLER FOR AN UNMANNED GROUND VEHICLE

S. SAHOO,S. C. SUBRAMANIAN,N. MAHALE,S. SRIVASTAVA 한국자동차공학회 2015 International journal of automotive technology Vol.16 No.1

This paper describes the design and implementation of a controller to track the desired heading angle for an unmanned ground vehicle (UGV) considering the limits on rotation of steering wheel and steering motor rate. The well-known “bicycle model” approximation, that considers the vehicle slip angle and ground-wheel interaction, has been used. In this work, combined closed loop control for steering motor and heading angle of the vehicle has been considered for better accuracy. The challenge in designing this control system is to include the actuator dynamics as the response time to steer the front wheel is in the same order as that of the heading angle dynamics of the vehicle. Experiments have been conducted, analysis of data collected is presented and the resulting mathematical representation is explained in detail. Results from both simulation and experimental implementation are also compared. It has been found that the vehicle controller can be tuned effectively to achieve the desired heading angle changes up to twenty degrees within three seconds when the vehicle is moving at a speed of 1.4 m/sec.

지면효과 속에 놓인 이중로터의 공력 특성에 대한 수치적 연구

김훈재,장호준,정지인,김병수 한국전산유체공학회 2022 한국전산유체공학회지 Vol.27 No.3

Multi-copters are used in various fields as unmanned aerial vehicles. Consequently, the stability of the operation conditions of the unmanned aerial vehicle and the improvement of aerodynamic characteristics are required. Therefore, this study is intended to examine the effect of the wake interaction between rotors in ground effect when a set of double rotors is positioned adjacent to the ground through an unsteady numerical analysis. For this reason, the rotor is positioned adjacent to the ground, and the thrust ratio is measured while changing the distance between the rotors which are rotating at a fixed rotational speed. With the ground height as z and the rotor radius as R, the smaller the height ratio(z/R), the higher the thrust. As the distance between the rotors became smaller, the collision and interaction between wing tip vortices of the rotor blades got stronger, and the flow was not properly propagated into the direction of the wake. It is shown that when the rotor gets closer to the ground, the flow could not be fed back in after flowing along the ground, so the thrust ratio due to the ground effect tends to decrease. With these results and analysis, the effect of wake interference between rotors on the ground effect could be confirmed.

공압부양 고속 지상운송체의 비정상 공력해석

조정현(Jeong-hyun Cho),조진수(Jin-soo Cho) 한국항공우주학회 2008 韓國航空宇宙學會誌 Vol.36 No.8

경계요소법을 이용하여 비평면 지면 위를 움직이는 공압부양 고속 지상운송체의 비정상 공력해석을 수행하였다. 비정상 공력해석을 위하여 시간전진법과 이에 연계한 자유후류를 도입하였다. 공압부양 고속 지상운송체가 채널 내를 움직일 때, 채널에 갇힌 공기에 의해 지면효과가 증가하여 운송체의 양력계수와 피칭모멘트 계수가 더욱 증가한다. 즉, 채널과 같은 비평면 지면은 운송체의 종방향 불안정성을 증가시킨다. 반면, 채널과 같은 비평면 지면에 의한 양력상승이 운송체 탠덤날개의 왼쪽과 오른쪽에 동일하게 발생하기 때문에 채널과 같은 비평면 지면효과가 운송체의 횡방향 안정성에 미치는 영향은 크지 않다. Unsteady aerodynamic analysis of an air-pressure-levitated high-speed ground vehicle moving over the nonplanar ground surface are performed using the boundary-element method. The potential flow solution is included in a time-stepping loop and the wake is captured as part of the solution. When the vehicle moving inside the channel, the lift coefficient and the pitching moment coefficient of the vehicle are increased further because the air trapped by the channel increases the ground effect. In other words, the nonplanar ground surface such as the channel decreases further the longitudinal stability of the vehicle. On the other hand, there is little difference between the ground and the channel in the lateral stability of the vehicle because the lift increment due to the nonplanar ground surface such as the channel takes place on both sides of the wing with the same rate of increase.

An innovative experimental on-road testing method and its demonstration on a prototype vehicle

José C. Páscoa,Francisco P. Brójo,Fernando C. Santos,Paulo O. Fael 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.6

Ground vehicle drag coefficient is herein obtained using an unconventional on-road test in real scale. At low-Re numbers, and as a function of velocity variations, transition introduces changes on the vehicle’s drag coefficient. Therefore, the drag coefficient must be obtained as a function of velocity. Traditionally, only an average drag coefficient value is usually obtained using the coast down method. To obtain the on-road, velocity dependent, drag coefficients we introduce a new approach. The aerodynamic resistance coefficient is obtained by towing the vehicle with and without an aerodynamic shield, in order to eliminate the rolling resistance component. A detailed description of the method, its associated techniques, and related errors is presented. We conclude that the present experimental procedure is needed when comparing the experimental drag coefficient against computational results, since numerical computations are usually performed in a velocity dependent framework. Further, the same on-road test procedure is herein used to obtain the rolling and aerodynamic drag coefficient for a prototype vehicle working in the transition regime.

경로주행 무인자동차 장애물회피를 위한 조향변화 최소화 조향기법

임준혁,여정윤,유승환,지규인 제어로봇시스템학회 2011 제어로봇시스템학회 국내학술대회 논문집 Vol.2011 No.5

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. 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.