• 한국항공우주학회지
• /
• 제48권5호
• /
• pp.373-381
• /
• 2020

쿼드로터는 대칭적인 구조로 모델링이 간단하지만 외란과 시스템의 불확실성에 민감하다는 단점이 있다. 쿼드로터의 제어를 위해 비교적 간단하게 적용이 가능한 PID 제어가 많이 연구되고 있지만, 비선형 시스템에서는 정밀한 제어가 힘들다는 단점이 있다. 본 논문에서는 이를 해결하기 위하여 외란과 시스템의 불확실성에 강인한 특징을 가지는 슈퍼 트위스팅 알고리즘(Super twisting algorithm)을 이용한 쿼드로터 제어를 제안한다. 이 제어기법을 이용하여 쿼드로터의 자세제어기를 구성하였다. 구성한 제어기의 성능을 검증하기 위해 시뮬레이션 및 실제 비행시험을 진행하였다. 제어기의 보다 객관적인 성능 검증을 위해 PID 제어와 성능 비교를 진행하였다.

• 한국항공운항학회지
• /
• 제9권1호
• /
• pp.5-13
• /
• 2001

There are many studies which reveal most of the accidents are related to pilot errors. Looking at each phase of flight, the accidents which occurred at the segments of take-off and landing consist of 70%, cause these phases need precise cooperations between pilots and ATC specialists to make sure every instructions understood and instruments to be normal. Therefore, the accidents of these phases leave great regrets and the price was enormous to people and equipments. Until now, most of the studies investigate the accident itself and very few show the relationships between pilots and air traffic controllers. This study analyzes the impacts of inter-dependence to mutual trust, cooperations and relationship efficiency between them who play important parts in flight. Based upon the findings, the inter-dependence has an effect on mutual trust and the latter influences to cooperations. Also, mutual trust and cooperations have a leading role in the relationship efficiency. It implies that mutual trust, cooperations, and the degree of inter-dependence are important factors to improve the relationships between them.

• 제어로봇시스템학회논문지
• /
• 제10권11호
• /
• pp.1028-1036
• /
• 2004

Ultrasonic sensors are widely used in mobile robot applications to recognize external environments by virtue that they are cheap, easy to use, and robust under varying lighting conditions. In most cases, a single ultrasonic sensor is used to measure the distance to an object based on time-of-flight (TOF) information, whereas multiple sensors are used to recognize the shape of an object, such as a comer, plane, or edge. However, the conventional sequential driving technique involves a long measurement time. This problem can be resolved by pulse coding of ultrasonic signals, which allows multi-sensors to be emitted simultaneously and adjacent objects to be distinguished. Accordingly, this paper presents a new simultaneous coded driving system for an ultrasonic sensor array for object recognition in autonomous mobile robots. The proposed system is designed and implemented. A micro-controller unit is implemented using a DSP, Polaroid 6500 ranging modules are modified for firing the coded signals, and a 5-channel coded signal generating board is made using a FPGA. To verify the proposed method, experiments were conducted in an environment with overlapping signals, and the flight distances fur each sensor were obtained from the received overlapping signals using correlations and conversion to a bipolar PCM-NRZ signal.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.265-270
• /
• 2005

This paper presents a new attitude stabilization and control of an unmanned helicopter based on neural network compensation. A systematic derivation on the dynamics of an unmanned small-scale helicopter is performed. Combined rotor-fuselage-tail dynamics is derived in body-fixed reference frame with its origin at the C.G. of the helicopter. And the resulting nonlinear equation of motion consists of 6-DOF air vehicle dynamics as well as the rotor flapping and engine torque equations. A simulation model was modified using the existing simulator for an unmanned helicopter dynamic model, which reflects the unmanned test helicopter(CNUHELI). The dynamic response of the refined model was compared with the flight test data. It can be shown that a good coincidence was accomplished between the real unmanned helicopter system and the mathematical model. This dynamic model was linearized for classical controller design using small perturbation method. A Neuro-PD control system was designed for both longitudinal and lateral flight modes, and the results were compared with the PD-only control response. Simulation results show that the proposed Neuro-PD control system demonstrates better performance.

• 반도체디스플레이기술학회지
• /
• 제19권1호
• /
• pp.11-16
• /
• 2020

In this paper, system that includes multiple unmanned aerial vehicles (UAVs) are considered. The vehicles are equipped with a mission computer for a specific mission and equipment. The mission equipment operates based on the time of mission computer. Also, data collected by flight computer and mission computer is saved with the time of each operating system. Generally, time offset between multiple computers always exists, though the computers are connected to the Internet. When the data collected by multiple computers is combined, the time offset causes damage on reliability of the combined data. Computers that connected to the Internet are synchronized by network time protocol (NTP). This paper proposes a system that the time of multiple mission computers are synchronized by the same NTP server to minimize the time offset. In the results of the measurement, the system time offset of multiple mission computer is maintained within 10ms from the system time of the server computer.

• 항공우주기술
• /
• 제12권1호
• /
• pp.54-63
• /
• 2013

항공기의 자세제어를 담당하는 각각의 비행 조종면에 중복안정성 등의 이유로 여러 개의 작동기를 연결하여 사용하고 있다. 다중 작동기들이 동시에 정확하게 같은 위치로 이동하지 않으면 비행조종면에 변형이 발생한다. 그 결과 변형된 조종면이 원래 상태로 복원하려는 힘에 의해 작동기들 간에 force fighting이 발생한다. 게다가 force fighting은 각 장치들의 초기 허용 오차 등에 의해서도 발생한다. 다중 작동기간의 force fighting 현상은 제어정밀도에 영향을 미치고 피로파괴의 원인이 되어 작동기와 비행조종면의 수명을 단축할 수도 있다. 본 논문에서는 두 개의 서보작동기를 사용하는 시스템의 force fighting을 감소하기 위하여 힘되먹임제어를 사용하는 제어기를 설계하였다.

• 한국추진공학회지
• /
• 제12권4호
• /
• pp.42-47
• /
• 2008

스마트무인기의 출력제어계통은 터보프롭 항공기와 유사한 피치 가버닝 개념으로 조종사가 엔진출력을 직접 조절하고 제어기는 프로펠러의 회전속도를 일정하게 유지하는 방식을 사용한다. PW206C 엔진은 회전익 항공기에 맞게 개발된 전자식엔진제어기를 갖춘 터보축 엔진으로 스마트무인기에서 요구되는 엔진제어개념과는 맞지 않는다. 따라서 엔진 출력을 전기식 작동기를 엔진의 출력조절레버에 연결하여 조절하는 수동방식을 사용한다. 본 논문에서는 엔진성능계산프로그램을 사용하여 엔진출력축속도, 비행고도 및 비행속도변화에 대한 엔진성능을 계산하여 각 비행조건에서의 출력조절레버각의 작동범위를 예측한다.

• 상하수도학회지
• /
• 제32권6호
• /
• pp.573-581
• /
• 2018

The purpose of this study is to evaluate the fixed wing type domestic UAV for monitoring of algae bloom in aquatic environment. The UAV used in this study is operated automatically in-flight using an automatic navigation device, and flies along a path targeting preconfigured GPS coordinates of desired measurement sites input by a flight path controller. The sensors used in this study were Sequoia multi-spectral cameras. The photographed images were processed using orthomosaics, georeferenced digital surface models, and 3D mapping software such as Pix4D. In this study, NDVI(Normalized distribution vegetation index) was used for estimating the concentration of chlorophyll-a in river. Based on the NDVI analysis, the distribution areas of chlorophyll-a could be analyzed. The UAV image was compared with a airborne image at a similar time and place. UAV images were found to be effective for monitoring of chlorophyll-a in river.

• 한국항공우주학회지
• /
• 제42권8호
• /
• pp.707-712
• /
• 2014

항공기의 연료량 지시계는 비행동안 잔여 연료량을 시현해주는 장치로 비행 중에는 정상적으로 성능을 발휘해야 한다. 한국형 기동헬기 연료량 지시계는 비행 중에 결함코드 "8888"을 시현하여 잔여 연료량을 확인하지 못해 비행안전에 영향을 끼쳤으며 고장탐구과정에서 개발과정 시 미흡하게 설계된 EMI/EMC 성능을 확인하였다. 본 논문에서는 비행 중 결함코드를 시현하는 원인인 전자기 외란에 의한 전원 불안정 및 CAN 통신 오류를 확인하고 이와 연관된 연료시스템의 개선 및 설계 적합성을 입증하였다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
• /
• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
• /
• pp.26.3-26.3
• /
• 2008

This research develops a GPS-based formation-flying testbed (FFTB) for formation navigation and control. The FFTB is a simulator in which spacecraft simulation and modeling software and loop test capabilities are integrated for test and evaluation of spacecraft navigation and formation control technologies. The FFTB is composed of a GPS measurement simulation computer, flight computer, environmental computer for providing true environment data and 3D visualization computer. The testbed can be simulated with one to two spacecraft, thus enabling a variety of navigation and control algorithms to be evaluated. In a formation flying simulation, GPS measurement are generated by a GPS measurement simulator to produce pseudorange, carrier phase measurements, which are collected and exchanged by the flight processors and subsequently processed in a navigation filter to generate relative and/or absolute state estimates. These state estimates are the fed into control algorithm, which are used to generate maneuvers required to maintain the formation. In this manner, the flight processor also serves as a test platform for candidate formation control algorithm. Such maneuvers are fed back through the controller and applied to the modeled truth trajectories to close simulation loop. Currently, The FFTB has a closed-loop capability of simulating a satellite navigation solution using software based GPS measurement, we move forward to improve using SPIRENT GPS RF signal simulator and space-based GPS receiver