• Journal of Institute of Control, Robotics and Systems
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• v.20 no.11
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• pp.1098-1102
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• 2014

Localization of aerial vehicles and map building of flight environments are key technologies for the autonomous flight of small UAVs. In outdoor environments, an unmanned aircraft can easily use a GPS (Global Positioning System) for its localization with acceptable accuracy. However, as the GPS is not available for use in indoor environments, the development of a SLAM (Simultaneous Localization and Mapping) system that is suitable for small UAVs is therefore needed. In this paper, we suggest a vision-based SLAM system that uses vision sensors and an AHRS (Attitude Heading Reference System) sensor. Feature points in images captured from the vision sensor are obtained by using GPU (Graphics Process Unit) based SIFT (Scale-invariant Feature Transform) algorithm. Those feature points are then combined with attitude information obtained from the AHRS to estimate the position of the small UAV. Based on the location information and color distribution, a Gaussian process model is generated, which could be a map. The experimental results show that the position of a small unmanned aircraft is estimated properly and the map of the environment is constructed by using the proposed method. Finally, the reliability of the proposed method is verified by comparing the difference between the estimated values and the actual values.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.9
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• pp.878-886
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• 2012

This paper investigates the implementation and flight test of realtime vision guided autopilot system based on virtual instrumentation platform. A graphical design process via virtual instrumentation platform is fully used for the image processing, communication between systems, vehicle dynamics control, and vision coupled guidance algorithms. A significatnt ojective of the algorithm is to achieve an environment robust autopilot despite wind and an irregular image acquisition condition. For a robust vision guided path tracking and hovering performance, the flight path guidance logic is combined in a multi conditional basis with the position estimation algorithm coupled with the vehicle attitude dynamics. An onboard flight test equipped with the developed realtime vision guided autopilot system is done using the rotary UAV system with full attitude control capability. Outdoor flight test demonstrated that the designed vision guided autopilot system succeeded in UAV's hovering on top of ground target within about several meters under geenral windy environment.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.215.2-215.2
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• 2012

우주물체 전자광학 감시체계(OWL: Optical Wide-field Patrol)는 전세계에 5개의 50cm급 자동 망원경과 1개의 2m급 망원경을 설치하여 인공위성의 궤도 정보를 얻는 시스템이다. 이 시스템을 운영하게 될 소프트웨어는 크게 두 부분으로 나누어지는데, 해외 원격지에 설치되는 관측소의 50cm급 망원경의 마운트와 검출기, 돔, 기상 측기, 전원 제어 장치를 통합하여 무인으로 관측을 수행하고 그 결과를 본부에 보고하며, 각 시스템을 안전하게 보호하는 기능을 갖는 SOS(Site Operating System)와, 스케줄러에 의하여 각 관측소에 필요한 관측 일정을 작성하여 전달하고 관측소의 운영 현황을 모니터링 하는 NOS(Network Operating System)로 구성된다. OWL OS를 위하여, 시스템을 전반적으로 운영하는 운영 시나리오를 설계하였으며, 이 시나리오에는 기상조건 악화와 장비 오류 등의 경우에 시스템을 보호하고 상황을 즉시 보고하는 비상사태 대처 방안을 포함하였다. 이러한 운영의 모든 단계에서 주기적 또는 필요시 로그 기록이 남도록 하였으며, 이 로그 기록을 바탕으로 사용자가 원할 때에 본부에서 운영상황을 요약하여 보여주는 각종 통계 자료를 작성하여 확인할 수 있도록 하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.597-604
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• 2016

The aim of this study was to prevent the decrease in crop output by disease and insect pests and excessive spraying of agricultural pesticides by application uniformity. A 3m height and 15km/h speed is difficult to maintain with an unmanned helicopter for aerial application, which has been affected by the controlling habits and methods or environmental factors, such as changes in the wind. Therefore, in this study, an aerial application system was design to be attached to an unmanned helicopter, which can allow a controlled application width and spray rate automatically and verified experimentally using Rmax of MS-AVIATION. The size of agricultural land was 50 m2 and nine water sensitive cards were arranged at 1.25m intervals in 5 rows with each row having a 10m interval from the position of 5m. The unmanned helicopter was flying at speeds ranging from 7.2km/h to 17.6km/h and heights ranging from 2.32m to 3.47m. The proposed aerial application system allowed application uniformity by making a valid spraying area of 7.5 m2 with 46423 particles distributed on average.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.9
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• pp.854-864
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• 2016

The use of small drone platform has become a popular topic in these days but its application for SAR operation has been little known due to the burden of the payload implementation. Drone platforms are distinguished from the conventional UAV system by the increased vulnerability to the turbulences, control-errors and poor motion stability. Consequently, sophisticated motion compensation may be required to guarantee the successful acquisition of high quality SAR imagery. Extremely limited power and mass budgets may prevent the use of additional hardwares for motion compensation and the difficulty of SAR focusing is further aggravated. In this paper, we have carried out a feasibility study of mico-SAR drone operation. We present the image acquisition results from the preliminary flight tests and a quality assessment is followed on the experimental SAR images. The in-flight motion errors derived from the unique drone movements are investigated and attempts have been made to compensate for the geometrical and phase errors caused by motions against the nominal trajectory. Finally, the successful operation of drone SAR system is validated through the focussed SAR images taken over test sites.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.5
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• pp.792-799
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• 2017

The real time unmanned monitoring system of an equipment's internal parts and condition requires the monitoring device to be able to stop at a set location on the rail. However, due to the slip between the driving surface and the roller, an error occurs between the actual position and the command position. In this paper, a method to compensate the position error due to the roller slip is proposed. A proximity sensor located at both ends of the rail detects the starting point and the maximum position pulse, linearly compensating the error between the angular position of the motor and the mechanically fixed starting and maximum position pulse of the rail in forward and reverse direction. Moreover, unlike the existing servo position controller, the motor adopts the position detection method of Hall sensor in BLDC (Brushless DC) and applies an algorithm for low-speed driving so that a stable position control is possible. The proposed rail guided unmanned monitoring system with driving slip compensator was tested to verify the effectiveness.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.548-551
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• 2010

A 150 lbf-thrust class micro turbojet engine has been developed. The engine could be applied to power plant for small aviation vehicle such as UAV, decoy and anti-radar missile and was designed with concepts that has small size, low-cost and high performance. A prototype was manufactured and performed the ground static test and high altitude test. This paper outlines the features and layout of 150 lbf turbojet engine and also describes the design characteristics and test results of the engine and components.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.407-408
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• 2016

A drone has been popularized to such an extent as to be seen in the near parks recently. The drone refers to an unmanned aerial vehicle(UVA) which can fly and be steered by a radio wave without a pilot and it has a airplane or helicopter shape. The drone was first started to be used from military purpose, but its usage has been expanded to the private such as broadcast shooting, crop-dusting, field discovery and hobby. However the drone that we can see often in the market is expansive, hard to be repaired when it broken down and has a discomfort of the short flight time. In this paper, to solve an uncomfortable talk on the cheap ATmega128 Using (Quad copter) drone for implementation. Axes gyroscope and accelerometers mcu between posture an attitude control, communications through drone control, pid. Receiver input them into transmitter signals of movements to control drone c the programming was implemented in on the basis of language.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.257-258
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• 2020

기존의 드론 조작은 초보자에게 어려웠다. 초보자의 경우 드론을 조종하다가 드론이 추락하거나 장애물에 걸려 프로펠러 등의 부품들이 손상되는 경우를 빈번하게 마주한다. 본 연구에서는 초보자 또한 드론 파손의 걱정 없이 드론의 조작을 더욱 쉽게 개선시키는 것을 전제로 뇌파와 보조입력인 음성인식을 이용한 드론 컨트롤러 기술을 적용하고자 한다. 현재 대중적으로 출시되어 있는 드론의 경우 호버링 기능을 포함시켜 드론의 추락 위험을 줄여주는 기능을 탑재하고 있다. 하지만 속도가 빠른 드론의 조작에 있어 미숙한 초보자들은 장애물과의 충돌 그리고 드론 착륙 시 기체손상 등의 위험에 대비하기 힘들다. 본 논문은 이러한 문제점들을 개선하기 위해 기존의 드론 컨트롤러 대신 특정한 동작을 상상할 때 발현되는 동작상상뇌파와 음성입력을 적용한 '동작상상뇌파와 음성인식을 이용한 드론 컨트롤러' 기술을 제안한다. 기존의 드론 컨트롤러와는 다르게 빅 데이터 처리기술인 머신러닝을 이용하여 뇌파 데이터를 처리하고 그 데이터들과 입력되는 뇌파 값을 비교하여 드론을 제어한다. 또한 뇌파의 발현이 안정적이지 못하는 상황을 대비한 보조입력인 음성인식을 이용하여 드론의 기체손상을 최소화 시킬 수 있다.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.3
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• pp.165-174
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• 2023

Unmanned Surface Vehicle (USV)'s berthing and unberthing is the most difficult maneuvering tasks and have the highest risk of accidents. In this paper, we designed a berthing/unberthing control algorithm given human joystick command for an USV equipped with a waterjet and a bow thruster. The berthing and unberthing maneuvers are performed remotely by a joystick operator at the Ground Control Center (GCC) where the status of USV and environmental situation can be monitored. We interpret the human joystick commands into USV's desired speed, yaw rate, and heading angle commands. next, we developed a control algorithm for the desired target values of MIMO actuators (engine speed, bucket step, nozzle angle, and bow thruster state) to follow the interpreted commands. The validity of the control algorithm is confirmed through simulations and sea trials at Gwang Am port.