• 제어로봇시스템학회논문지
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• 제17권5호
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• pp.436-443
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• 2011

Recognition of structures in urban environments is a fundamental ability for unmanned ground vehicles. In this paper we propose the geometrical featured voxel which has not only 3-D coordinates but also the type of geometrical properties of point cloud. Instead of dealing with a huge amount of point cloud collected by range sensors in urban, the proposed voxel can efficiently represent and save 3-D urban structures without loss of geometrical properties. We also provide an urban structure classification algorithm by using the proposed voxel and machine learning techniques. The proposed method enables to recognize urban environments around unmanned ground vehicles quickly. In order to evaluate an ability of the proposed map representation and the urban structure classification algorithm, our vehicle equipped with the sensor system collected range data and pose data in campus and experimental results have been shown in this paper.

• 대한조선학회논문집
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• 제46권2호
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• pp.114-126
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• 2009

The authors adopt the Unmanned Undersea Vehicle(UUV), which has taken the shape of manta(Sohn et al. 2006). They call here it Manta-type Unmanned Undersea Test Vehicle(MUUTV). MUUTV is based on the same design concept as UUV called Manta Test Vehicle, which was originally built and operated by the Naval Undersea Warfare Center(Lisiewicz and French 2000, Sirmalis et al. 2001). In order to evaluate manoeuvring motion characteristics of MUUTV, numerical simulation technique has been utilized. Previous mathematical model on manoeuvring motion of MUUTV(Sohn et al. 2006) is basically adopted. Result of static experiment carried out in circulating water channel and a part of NSRDC standard model(Feldman 1979) on rotational mode are supplemented. Some of the hydrodynamic derivatives are obtained from model experiment in circulating water channel and the rest of them are estimated.

• 한국군사과학기술학회지
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• 제15권4호
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• pp.424-434
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• 2012

This paper presents a path planning algorithm of the unmanned aerial vehicle for the neutralization of the enemy firepower. The long range firepower of the ememy is usually located at the rear side of the mountain which is difficult to bomb. The path planner not only consider the differential constraints of the Unmanned Aerial Vehicle (UAV) but also consider the final approaching angle constraint. This problem is easily solved by incorporating the analytical upper bounded continuous curvature path smoothing algorithm into the Rapidly Exploring Random Tree (RRT) planner. The proposed algorithm can build a feasible path satisfying the kinematic constraints of the UAV on the fly. In addition, the curvatures of the path are continuous over the whole path. Simulation results show that the proposed algorithm can generate a feasible path of the UAV for the bombing mission regardless of the posture of the tunnel.

• 한국군사과학기술학회지
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• 제18권4호
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• pp.451-458
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• 2015

This paper handles self-collision avoidance for a rescue robot with redundant manipulators. In order to detect all available self-collisions in advance, minimum distances between arbitrary robot parts should be monitored in real-time. For the minimum distance estimation, we suggest a modified method from a previous skeleton algorithm which has less computation burden and realize collision avoidance based on a potential function using the proposed algorithm. The resultant command by collision avoidance should not disturb a given primary task, so null-space of joint solution from a CLIK is utilized for collision avoidance by a gradient projection method.

• 한국군사과학기술학회지
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• 제23권4호
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• pp.311-318
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• 2020

This study investigates the performance and blade airloads for a rigid coaxial rotor of high-speed compound unmanned rotorcrafts. The present compound unmanned rotorcraft uses not only a rigid coaxial rotor, but also wings and propellers for high-speed flights. For the rigid coaxial rotor in this work, CAMRAD II, a rotorcraft comprehensive analysis code, is used to study the performance at a flight speed of up to 250 knots and blade section lift forces at 230 knots. As the flight speed increases, the rotor power decreases; however, the power of propellers increases to overcome the drag force of a rotorcraft in high-speed flight. The effective lift-to-drag ratio of a rotor has the maximum value of about 11.6 which is much higher than the value of the conventional helicopter. The blade section lift forces of the upper and lower rotors at 230 knots show the similar variation trends for one rotor revolution, and the impulses because of the aerodynamic interaction between both rotors are observed.

• Journal of Biosystems Engineering
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• 제34권2호
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• pp.89-94
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• 2009

Aerial application using an agricultural unmanned helicopter was suggested for an alternative against current pesticide application methods. Centrifugal clutches play important roles in the performance and safety of the helicopter operation. A previous study analyzed and verified the power transfer theory of the guide type centrifugal clutch. Based on the clutch theory, optimal designs of the clutch became possible and feasible using a simulation method. Design criteria of the clutch were the power transfer capacity of 24.66 kW(33.5 PS) at the rated engine speed and the engaging range speed of 3,000${\sim}$3,500 rpm. Various designs were accomplished using the simulation. An optimal clutch was simulated by determining the values of spring constant and mass of friction sector, which were 94,700 N/m and 123.7 g, respectively. The design performed the power capacity of 24.86 kW(33.8 PS) and engagement speed of 3,069 rpm, meeting the design criteria. Using the designed clutch, an efficient transfer of the power would be possible for the unmanned agricultural helicopter.

• 한국항해항만학회지
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• 제35권2호
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• pp.121-130
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• 2011

The localization of vehicle is an important part of an unmanned vehicle control problem. Pseudolite ultrasonic system(PUS) is the method to find an absolute position with a high accuracy by using ultrasonic sensor. And Gyro is the inertial sensor to measure yaw angle of vehicle. PUS can be able to estimate the position of mobile robot precisely, in which errors are not accumulated. And Gyro is a more faster measure method than PUS. In this paper, we suggest a more accuracy method of calculating PUS which is numerical analysis approach named Newtonian method. And also propose the fusion method to increase the accuracy of estimated angle on moving vehicle by using PUS and Gyro integrated system by Kalman filtering. To control the 4WS unmanned vehicle, the trajectory following algorithm is suggested. And the new concept arbitration of goal controller is suggested. This method considers the desirability function of vehicle state. Finally, the performances of Newtonian method and designed controller were verified from the experimental results with the 4WS vehicle scaled 1/10.

• 한국해양공학회지
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• 제30권5호
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• pp.426-430
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• 2016

Recently, many unmanned surface vehicles (USVs) have been developed and researched for various fields such as the military, environment, and robotics. In order to perform purpose specific tasks, common autonomous navigation technologies are needed. Obstacle avoidance is important for safe autonomous navigation. This paper describes a vector field histogram+ (VFH+) based obstacle avoidance method that uses the monocular vision of an unmanned surface vehicle. After creating a polar histogram using VFH+, an open space without the histogram is selected in the moving direction. Instead of distance sensor data, monocular vision data are used for make the polar histogram, which includes obstacle information. An object on the water is recognized as an obstacle because this method is for USV. The results of a simulation with sea images showed that we can verify a change in the moving direction according to the position of objects.

• 한국멀티미디어학회논문지
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• 제24권10호
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• pp.1346-1357
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• 2021

The drone technology, which is receiving a lot of attention due to the 4th industrial revolution, requires an Unmanned Aerial Vehicles'(UAVs) flight path search algorithm for automatic operation and driver assistance. Various studies related to flight path prediction and recommendation algorithms are being actively conducted, and many studies using the A-Star algorithm are typically performed. In this paper, we propose an Optimal 3D Flight Path Recommendation System for unmanned aerial vehicles. The proposed system was implemented and simulated in Unity 3D, and by indicating the meaning of the route using three different colors, such as planned route, the recommended route, and the current route were compared each other. And obstacle response experiments were conducted to cope with bad weather. It is expected that the proposed system will provide an improved user experience compared to the existing system through accurate and real-time adaptive path prediction in a 3D mixed reality environment.

• 한국융합학회논문지
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• 제12권7호
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• pp.1-6
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• 2021

현재, 코로나19등 바이러스 감염이 일상화 되어 있고, 비대면 ICT 서비스를 위한 분야에 무인시스템에 대한 관심이 증가하고 있다. 본 논문에서는 방송기능을 가진 IP PBX를 이용하여 원격으로 중, 소형 점포를 중앙에서 영상과 음성을 통해 성공적으로 관제할 수 있는 기능과 성능을 시험을 통하여 입증하였다. 현재 완전 무인 시스템은 여러 가지 기술적 문제로 신뢰성이 없지만, 본 논문에서 개발한 중앙관제시스템은 영상과 음성을 통해 관제사가 출입과 내부를 모니터링 함으로 직접 소비자를 관제할 수 있어 매우 효율적이고 신뢰를 할 수 있는 시스템이다. 향후에는 A.I 기술을 활용한 완전 무인 원격제어 시스템을 연구할 예정이다.