• Journal of Institute of Control, Robotics and Systems
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• v.20 no.7
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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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• 2005.06a
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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.

• Journal of Advanced Navigation Technology
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• v.9 no.2
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• pp.87-92
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• 2005

An altitude control using a fuzzy controller was performed for a series of research for autonomous flight control of industrial unmanned helicopters. The 3m class gasoline engined unmanned helicopter was designed, and using the designed specifications, Takagi-Sugeno-Kang type fuzzy controller was designed. The input membership functions were generated using target altitude, altitude error and velocity of unmanned helicopter. With these membership functions, the control inputs for altitude control were calculated. These control input signal can control the main rotor's pitch and determine the velocity and altitude of the unmanned helicopter. Also, the altitude control performance of the designed fuzzy controller was evaluated by computer simulations

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.5
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• pp.383-388
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• 2021

Air-breathing engines used in aircraft have a performance limit as the altitude increases, and this determines the service and absolute ceiling altitude. The method of maintaining altitude and speed in a fixed-wing aircraft in level flight using classical control method is generally using thrust for speed increase/deceleration and pitch attitude for altitude increase/decrease. If this method is used near the service ceiling altitude, increasing the pitch to reduce the altitude error results in a speed reduction. Therefore, it is necessary to use a control method that maintains the speed first using the pitch attitude. Especially in the case of unmanned aerial vehicles, these two methods should be automatically available at the right time. In this paper, we propose a method of switching the speed and altitude maintenance algorithm near service ceiling altitude.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.12
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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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• v.2 no.1
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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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• v.16 no.2
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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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• v.14 no.1
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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.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.6
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• pp.393-400
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• 2022

The Divert and Attitude Control System(DACS) used in high-altitude engagements is expensive and complex. In this paper, we design a high-altitude terminal guidance and control loop of guided-missile equipped with a Thrust Vector Control(TVC) that is less expensive and simpler than DACS. The proposed system utilizes a quaternion feedback control technique to track the thrust attitude command converted from the acceleration command of true proportional navigation guidance. The performance analysis of the proposed terminal guidance and control loop is conducted through engagement simulations against ballistic targets at a high altitude.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.2
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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.