• 대한조선학회논문집
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• 제40권1호
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• pp.8-19
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• 2003

Special purpose vessels such as drillship and ocean research vessels install the DPS(Dynamic Positioning System) to maintain the position and heading for long-time operation. This paper deals with the design parameters for the control theory and filter algorithms of DP system. for the environmental loadings wind forces, current forces and wave forces were considered. In order to estimate the low frequency motions without first-order wave motion, the Kalman filter was used and it was assumed that the first-order wave forces correspond to system noises and first-order wave motions are measurement noises. In this simulation, the length of research vessel is 65 meters and it has four thrusters to maintain the position. The ability of keeping position and heading was confirmed. For the calculation of thruster input the LQR and LOI control theory were adopted and the effects of gain were investigated.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.325-332
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• 2000

The objective of this research work is to develop an autonomous levee-weeding robot. In this paper, pathway control system for the robot is developed and simulated. A prototype autonomous vehicle for levee weeding is also developed and used in the actual test. The results obtained in this research work is summarized as follows; 1) The simulated typical time history of lateral displacements and heading angle of the vehicle in straight run shows that the vehicle tendency is always to achieve the target path from any of its deviated position and heading angle. 2) The test run on an asphalt surface by the prototype crawler-type vehicle is in good agreement with the simulation results.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.175-175
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• 2000

In this Paper we propose a navigation algorithm which can be used to estimate state vectors such as position and velocity for its motion control using multi-sensor output measurements. The output measurement we will use in estimating the state is a series of known multi-sensor asynchronous outputs with measurement noise. This paper investigates the Extended Kalman Filtering method to merge asynchronous heading, heading rate, velocity of DVL, and SSBL information to produce a single state vector. Different complexity of Kalman Filter, with biases and measurement noise, are investigated with theoretically data from KRISO's AUV. All levels of complexity of the Kalman Filters are shown to be much more close and smooth to real trajectories then the basic underwater acoustic navigation system comment)'used aboard underwater vehicle.

• 제어로봇시스템학회논문지
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• 제14권2호
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• pp.118-124
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• 2008

Recently fishing industry is interested in efficiency and automation to acquire the international competitive power of national fishing industry. As an automation device of fishing boat, there are electric compasses using GPS and terrestrial magnetic sensor. Electric compass can be minimum size, high effectiveness with keeping the characteristic of a magnetic compass. This can be used a heading angle sensor to construct auto-navigation system in a small size ship. This paper develop electronic compass system that has serial output signal in NMEA 0183 and demonstrates the possibility of the electronics compass in navigation system for a small sized ship.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.361-366
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• 1991

A ground and airborne control system for remotely piloted vehicle (RPV) is described. 1) Ground control system 2) airborne control system 3) the method of measuring aircraft attitude and heading 4) autopilot 5) the method of treating emergency status 6) the method of transmitting and receiving communication data 7) the method of displaying aircraft status 8) the characteristics of the aircraft control system are discussed in some detail.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.463-467
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• 2005

In this paper, the guidance law applicable to formation flight of UAV in three-dimensional space is proposed. The concept of miss distance, which is commonly used in the missile guidance laws, and Lyapunov stability theorem are effectively combined to obtain the guidance commands of the wingmen. The propose guidance law is easily integrated into the existing flight control system because the guidance commands are given in terms of velocity, flight path angle and heading angle to form the prescribed formation. In this guidance law, communication is required between the leader and the wingmen to achieve autonomous formation. The wingmen are only required the current position and velocity information of the leader vehicle. The performance of the proposed guidance law is evaluated using the complete nonlinear 6-DOF aircraft system. This system is integrated with nonlinear aerodynamic and engine characteristics, actuator servo limitations for control surfaces, various stability and control augmentation system, and autopilots. From the nonlinear simulation results, the new guidance law for formation flight shows that the vehicles involved in formation flight are perfectly formed the prescribed formation satisfying the several constraints such as final velocity, flight path angle, and heading angle.

• 전기학회논문지
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• 제62권6호
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• pp.852-862
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• 2013

This paper proposes a target tracking control method for wheeled mobile robots with nonholonomic constraints by using a backstepping-like feedback linearization. For the target tracking, we apply a vision system to mobile robots to obtain the relative posture information between the mobile robot and the target. The robots do not use the sensors to obtain the velocity information in this paper and therefore assumed the unknown velocities of both mobile robot and target. Instead, the proposed method uses only the maximum velocity information of the mobile robot and target. First, the pseudo command for the forward linear velocity and the heading direction angle are designed based on the kinematics by using the obtained image information. Then, the actual control inputs are designed to make the actual forward linear velocity and the heading direction angle follow the pseudo commands. Through simulations and experiments for the mobile robot we have confirmed that the proposed control method is able to track target even when the velocity sensors are not used at all.

• 한국초지조사료학회지
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• 제18권3호
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• pp.259-266
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• 1998

A field experiment was carried out to determine the effects of mechanical and chemical drying agents at mowing on the field drying rate and hay quality of orchardgrass dominant pasture plants. The mower conditioner /chemical drying agent ($K_2CO_3$ 2% conditioning, $K_2CO_3$ 2% + conditioning and control) were treated at different harvest stages (late boot, heading and bloom stage) for hastening hay manufacture in 1996. After field dry, four square bales were made by hay baler, and the visual estimation and nutritive value of hay were evaluated after storing two months. The field drying rate of pasture plants was higher with delayed stage of harvest, and mechanical and mechanical + chemical, but chemical alone was very low. In mower conditioning, the duration of field dry was shortened by 0.5 to 1 day compared with $K_2CO_3$ and 1.5 to 2 days compared with control. The dry matter loss of hay was reduced by late harvest and mechanical, and mechanical + chemical, but the score by chemical alone was very low. The visual score (leafiness, green color, odor and softness) of hay after storage was high in mechanical and mechanical + chemical, but the score by chemical alone was very low. Nutritive value (ADF, NDF, digestibility, and relative feed value) of hay was also high with treatment of mechanical and mechanical + chemical, but the quality by chemical alone was similar compared with control. The quality of hay was very low when harvested at bloom stage. In conclusion, mower conditioning can enhance the field drying rate of orchardgrass dominant pasture plants, however the drying efficiency of chemical drying agent was very low. Harvesting at early heading to heading stage was recommened for manufacture of high quality hay.

• 한국잡초학회지
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• 제12권1호
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• pp.31-38
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• 1992

생장조정제(生長調整劑) 처리(處理)가 수도(水稻)의 생육(生育) 및 도복관련형질(倒伏關聯形質)에 미치는 효과(效果)를 시험(試險)한 결과(結果)를 요약(要約)하면 다음과 같다. 1. Inabenfide, paclobutrazol, uniconazole 세 약제(藥劑) 모두 초장(草長) 억제효과(抑制效果)가 있었으며 약량(藥量)이 많을수록 억제효과(抑制效果)가 컸고, inabenfide는 출수전(出穗前) 30 일(日), paclobutrazol과 uniconazole은 출수전(出穗前) 20일(日) 처리(處理)에서 가장 억제(抑制)되었다. 2. Inabenfide는 하위절간(下位絶間)인 제(第) 4절간(絶間)은 억제(抑制)시킨데 비(比)하여 paclobutrazol과 uniconazole은 상위절간(上位絶間)인 제(第)3, 2 절간(絶間)을 각각(各各) 크게 억제(抑制)시켰다. 3. 약제처리(藥劑處理)에 의(依)한 간벽(稈壁)두께는 무처리(無處理)보다 전반적(全般的)으로 두꺼워지는 경향(傾向)이었으나 처리시기별(處理時期別) 약량별(藥量別) 일정(藥量別)한 차이(差異)는 보이지 않았다. 4. 출수기(出穗期)는 inabenfide 처리시(處理時) 무처리(無處理)와 동일(同一)하였으나 paclobutrazol과 uniconazol 처리시(處理時) 1~2일(日) 정도(程度) 지연(遲延)되었다. 5. 도복지수(倒伏指數)는 inabenfide의 경우(境遇) 출수전(出穗前) 30 일(日), 10a당(當) 성분량(成分量)으로 160g 처리시(處理時) 가장 낮은 지수(指數)를 보였으며 paclobutrazol과 uniconazale은 출수전(出穗前) 15일(日)에 10a당各(當) 각(各)12g, 1.2g 처리시(處理時) 가장 낮은 지수(指數)를 보였다. 6. 전약제(全藥劑) 처리구(處理區)에서 도복(倒伏)이 되지 않았던 반면(反面) 무처리구(無處理區)에서는 완전(完全)히 도복(倒伏)되었다. 7. 수량(收量)은 도복(倒伏)이 경감(輕減)되므로서 10~12%의 감수(減收)가 억제(抑制)되었다. 8. 결론적(結論的)으로 inabenfide는 출수전(出穗前) 40~30일(日)에 10a당(當) 성분량(成分量)으로 120~160g, paclobutrazol과 uniconazole은 출수전(出穗前) 15일(日)에 각각(各各) 12g, 1.2g을 처리(處理)하는 것이 가장 적당(適當)할 것으로 생각된다.

• 해양환경안전학회지
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• 제22권1호
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• pp.129-137
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• 2016

본 연구의 목적은 가까운 미래의 선박운동정보를 이용하는 피드포워드 제어알고리즘과 FPSO 운동 수치 시뮬레이션 모델을 개발하고 시뮬레이션을 통하여 제어알고리즘의 성능을 검증하는 것이다. 본 논문에서는 조류, 바람, 파력 등의 환경하중에 의하여 발생한 선체운동의 미래 예측치를 활용한 피드포워드 제어력을 추가적으로 가지는 Dynamic Positioning System에 대하여 연구한다. 먼저, 조류력, 풍력 및 파력에 대한 수학모델을 선정하여 환경하중에서의 선체운동을 계산하고, 현재의 선체운동 값과 Brown 지수평활 예측모형을 활용하여 미래 선체운동 값을 예측하였다. 또한 위치 유지와 Heading angle 제어를 위한 제어력을 PID(Proportional-Integral-Derivative)이론을 이용하여 결정한 피드백 제어기와 미래 선체운동 값을 이용하여 결정한 피드포워드 제어기로 구성하였다. 그리고 각 Thruster에 요구되는 추력은 라그랑지승수법을 활용하여 분배하였다. 마지막으로 FPSO(Floating Production Storage and Offloading)의 운동과 Dynamic Positioning System에 대한 시뮬레이션 모델을 구축하여 선박의 위치 및 Heading angle 제어에 관한 시뮬레이션을 수행하여 제안하는 피드백 제어기와 피드포워드 제어기를 동시에 가지는 제어시스템의 성능을 평가하였다. 본 연구의 결과, 피드백 및 피드 포워드 제어기가 적용된 DPS 제어시스템이 기존의 피드백 제어기보다 위치유지 및 헤딩각 유지 능력에서 개선되었고 각 Thruster에 요구되는 평균 제어력 및 최대 제어력의 크기도 감소함을 보였다. 이에 따라 DPS에 요구되는 동력 감축과 Azimuth Thruster 용량의 감소로 인하여 비용 절감의 효과를 기대할 수 있다.