• 제어로봇시스템학회논문지
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• 제20권7호
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• pp.724-729
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• 2014

This paper presents the altitude control of a quadrotor system under the disturbance. The altitude is measured by an ultra sonic sensor attached at the bottom of the quadrotor system and the measured altitude data are used in the time-delayed controller. To test the robustness of the controller, a weight attached to the center of the system is dropped intentionally several times to cause disturbances to the system. Performances of the altitude control by the PID control and time-delayed control method are compared experimentally. Experimental studies are conducted to verify the outperformance of the time-delayed controller for controlling the altitude of the quadrotor system under disturbances.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.590-593
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• 2005

Unmanned Helicopter has several abilities such as vertical Take off, hovering, low speed flight at low altitude. Such vehicles are becoming popular in actual applications such as search and rescue, aerial reconnaissance and surveillance. These vehicles also used under risky environments without threatening the life of a pilot. Since a small unmanned helicopter is very sensitive to environmental conditions, it is generally known that the flight control is very difficult problems. The nonlinear adaptive fuzzy controller design procedure and its applications for altitude control of unmanned helicopter were described in the paper. This research was concentrated on describing the design methodologies of altitude controller design for small unmanned helicopter acquiring autonomous take off and vertical movement. The design methodologies and performance of the altitude controller were simulated and verified with an adaptive fuzzy controller. Throughout simulation results, I showed that the proposed adaptive controllers have enhanced control performance such as robustness, effectiveness and safety, in the altitude control of the unmanned helicopter.

• 한국항행학회논문지
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• 제9권2호
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• pp.87-92
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• 2005

본 연구에서는 산업용 무인 헬리콥터의 자율비행을 위한 일환으로 퍼지 제어기를 이용하여 고도제어를 하였다. 본 논문에서는 가솔린 엔진을 사용하는 전장 3m급의 무인 헬리콥터를 설계하고 이의 재원을 이용하여 Takagi-Sugeno-Kang 형의 퍼지 제어기법으로 고도 제어기를 구성하였다. 목표 고도값과 고도의 오차, 그리고 속도를 이용하여 입력 선형 맴버쉽 함수를 생성하였다. 이렇게 구성된 멤버쉽 함수를 이용 제어입력을 생성하였고, 생성된 제어입력을 이용하여 메인 로터의 피지를 제어하고 그 결과를 이용하여 속도와 고도를 구하였다. 시뮬레이션을 통하여 설계한 퍼지제어기의 고도제어 성능을 평가하였다.

• 한국항공우주학회지
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• 제49권5호
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• pp.383-388
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• 2021

항공기에 사용되는 공기 흡입식 엔진은 고도가 높아질수록 성능의 한계를 가지며, 이는 실용상승한도(Service Ceiling)와 절대상승한도(Absolute Ceiling) 고도로 나타나게 된다. 고정익 항공기가 순항비행(Level Flight) 상태에서 고전제어기법(Classical Control)을 사용하여 고도 및 속도 유지를 하는 방법은 일반적으로 속도 증/감속을 위해 추력을 사용하고, 고도 증/감을 위해 피치 자세를 사용한다. 실용 상승 한도 고도 부근에서 이 방법을 사용하는 경우 고도 오차를 줄이기 위해 피치를 증가시키면 속도 감속으로 나타나게 된다. 따라서 피치 자세를 사용하여 속도를 먼저 유지하는 방법을 사용해야 한다. 특히 무인기의 경우 이 두 가지의 방법을 자동으로 적절한 시점에 사용할 수 있어야 한다. 본 논문에서는 고도 상승률이 둔화되는 실용상승한도 부근에서 속도와 고도유지 알고리즘의 전환 방법을 제안하고, 비행시험을 통해 개선된 효과를 확인하였다.

• 제어로봇시스템학회논문지
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• 제14권12호
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• pp.1232-1237
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• 2008

This paper introduces an application of wavelet analysis to the sensor fusion of GPS/INS/baroaltimeter. Using wavelet analysis the baro-inertial altitude is decomposed into the low frequency content and the high frequency content. The high frequency components, 'details', represent the perturbed altitude change from the long time trend. GPS altitude is also broken down by a wavelet decomposition. The low frequency components, 'approximations', of the decomposed signal address the long-term trend of altitude. It is proposed that the final altitude be determined as the sum of both the details of the baro-inertial altitude and the approximations of GPS altitude. Then the final altitude exclude long-term baro-inertial errors and short-term GPS errors. Finally, it is shown from the test results that the proposed method produces continuous and sensitive altitude successfully.

• International Journal of Aeronautical and Space Sciences
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• 제2권1호
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• pp.93-102
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• 2001

Flight control design for the autonomous waypoint navigation of aircraft is presented in this study. The waypoints are defined in terms of desired longitude and latitude. The control design is conducted in longitudinal and lateral directions, respectively. The lateral control is based upon coordinated turn strategy for which no sideslip is allowed under the turning maneuver. The longitudinal control is mainly focused on altitude hold during navigation. Neural network control approach is applied to the altitude-hold mode control. Simulation of the proposed control strategy has been performed under various conditions. A graphical simulation tool was developed to visually demonstrate the control technique developed in this study. A method to simulate the gas turbine transient behavior is developed. The basic principles of the method.

• Journal of information and communication convergence engineering
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• 제16권2호
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• pp.78-83
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• 2018

Rapidity and accuracy are important considerations when a drone is employed in a wide surveillance area to detect a target. They are more important when the scope of application is a search and rescue operation or the monitoring of natural disasters, which may require prompt warnings and response. During the actual operation of a drone, rapidity and accuracy are associated with the change in the altitude of the drone. The aim of this study is to analyze the characteristics of drones at varying altitudes and prove that altitude is a relevant factor in the performance of drones. Herein, the characteristics of the drone at varying altitudes were analyzed through several search simulations. The results suggest that a high-altitude drone is relatively advantageous compared to a low-altitude drone in a probability-based target search, and that the search altitude is also a very important and fundamental factor in target search by drones.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제14권1호
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• pp.26-33
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• 2014

This study addresses the control problem of an unmanned aerial vehicle (UAV) during the transition period when the flying mode changes from hovering to translational motion in the horizontal plane. First, we introduce a compensation algorithm that improves height stabilization and reduces altitude drop. The main principle is to incorporate pitch and roll measurements into the feedforward term of the altitude controller to provide a larger thrust force. To further improve altitude control, we propose the fuzzy logic controller that improves system behavior. Simulation results presented in the paper highlight the effectiveness of the proposed controllers.

• 한국항공우주학회지
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• 제50권6호
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• pp.393-400
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• 2022

고고도 교전 시 사용되는 궤도수정 및 자세제어 시스템(Divert and Attitude Control System, DACS)은 고가이며 복잡하다. 본 논문에서는 비교적 단순하고 저가인 추력벡터제어(Thrust Vector Control, TVC)를 탑재한 유도탄의 고고도 종말 유도조종 루프를 제안한다. 본 유도조종 루프는 쿼터니언 피드백 제어기법을 이용하여 진 비례항법유도로 산출된 가속도 명령으로부터 변환된 추력 자세각 명령을 추종하며 유도를 수행한다. 고고도에서 탄도탄에 대한 교전 시뮬레이션을 통하여 제안한 유도조종 루프의 성능을 분석한다.

• Asian-Australasian Journal of Animal Sciences
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• 제24권2호
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• pp.246-249
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• 2011

The present study was carried out on broilers to study the effect of oral administration of vitamin E and selenium (E-care Se) on growth performance, haematological and biochemical parameters for a period of 42 days (6 weeks). A total of 90 oneday-old broiler chicks were divided into three equal groups: $T_1$, $T_2$ and $T_3$. Group T1 was maintained as control and was fed only with the basal diet throughout the experimental period. Two experimental diets, $T_2$ and $T_3$, were formulated to contain an additional 100 g (150 IU vitamin E/kg+0.5 mg Se/kg) and 200 g (300 IU vitamin E/kg+1.0 mg Se/kg) of E-care Se which was the source of vitamin E and selenium. Body weight was significantly (p<0.05) higher in antioxidant-treated groups compared to the control group. There were no significant differences in feed conversion ratio (FCR). Blood samples were collected from the jugular vein for haematological (TEC, Hb, PCV and ESR) and biochemical (GOT and GPT) study. Body weight was increased significantly in both treated groups compared with the control group and highest body weights were recorded in group $T_2$. TEC, PCV and Hb content increased significantly (p<0.01) in the treated groups as compared to the control group, but ESR, GOT and GPT values decreased significantly (p<0.01) in both treated groups as compared to the control group. The result reveals that use of antioxidants (vitamin E and selenium) is an effective way of getting the best result in terms of body weight gain and haemato-biochemical profiles in broiler birds at high altitude.