• Journal of Institute of Control, Robotics and Systems
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• v.19 no.2
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• pp.164-170
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• 2013

Quadrotor UAV (Unmanned Aerial Vehicle) is a flying robotic platform which has drawn lots of attention in the recent years. The attraction comes from the fact that it is able to perform agile VTOL (Vertical Take-Off Landing) and hovering functions. In addition, the efficient modular structure composed of four electric rotors makes its design easier compared to other single-rotor type helicopters. In many cases, a quadrotor often utilizes vision systems in order to obtain altitude control and navigation solution in hostile environments where GPS receivers are not working or deniable. For carrying out their successful missions, it is essential for flight control systems to have fast and stable control responses of heading angle outputs. This paper presents a Fuzzy Logic based lateral PI controller to stabilize and control the quadrotor vehicle equipped with vision systems. The advantage of using the fuzzy based PI controller lies in the fact that it could acquire a desired output response of a heading angle even in presence of disturbances and uncertainties. The performance comparison of the newly proposed Fuzzy-PI controller and the conventional PI controller was carried out with various simulation results.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.3-4
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• 2011

In this study, the nonlinear mathematical model of Manta type UUV is derived the hydrodynamic derivatives and the sliding mode controller of Manta type UUV test bed is designed. The sliding mode control scheme is used for robust control on the nonlinear motion. The designed controller is used the depth and heading control. It is based on the 6 DOF mathematical model with effect of the ocean currents. As a result, the performance of the designed controller is confirmed by computer simulation.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.57-62
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• 2003

This paper describes the design and simulation of a multivariable optimal control system for the combined speed, heading and depth control of a Semi-Autonomous Underwater Vehicle (SAUV) developed in Korea Ocean Research and Development Institute (KRODI). The SAUV is a test-bed for the evaluation of the navigation and manipulator technologies developed for a mine disposal vehicle (MDV) in military use and for a light working underwater vehicle in scientific use. The vehicle was designed to control its cruising speed, heading and depth with 4 horizontal thrusters installed at the rear of the hull. Therefore, the decoupled control methods are limited to apply to the SAUV because the thrust forces are highly coupled with the surging, yawing, and pitching motion of the vehicle. The multivariable Linear Quadratic (LQ) control method is chosen to control steering and diving in variable speed motion automatically. A series of simulation is carried out with fully nonlinear six degree of freedom dynamic model to validate the controller.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.8
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• pp.726-732
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• 2005

This paper proposes an autolanding guidance and control algorithm with the lateral guidance law. This algorithm is basically formulated and designed in feedback linearization based on singular perturbation. Main features of this algorithm are two facts. One of those is that when a certain situation happens that airplane must realign to the runway suddenly assigned due to unexpected environment change around the landing site, the heading guidance in this algorithm is very valuable, and the other is the fact that the inner loop control of this algorithm is able to be designed directly based on the Handling Quality Requirements that most flight control systems must be satisfied with. To illustrate the potential of this algorithm, 6-DOF nonlinear simulation based on the nonlinear airplane model shown in Ref.[11] is carried out. The simulation results showed that the altitude response to the given landing trajectory is accurate, and the airplane heading alignment to the assigned runway from the lateral deviation is successful. It is noted that this algorithm is also applicable to unmanned aerial vehicle, which can be retrieved in autolanding technique, where the runway far retrieving the vehicle is in any direction for example at war field.

• Journal of Navigation and Port Research
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• v.35 no.5
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• pp.359-363
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• 2011

In this paper, automatic control system for the Manta UUV are constructed for the diving and steering maneuver. PID controller and Fuzzy controller are adopted in this system. Based on the 6DOF dynamic equation, simulation program has been developed using the Matlab. Using this program, depth control system and heading control system with tidal current are evaluated.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.2
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• pp.181-187
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• 2018

In order for the probe to perform ocean exploration and survey research, it is necessary to adjust the position of the ship as desired by dynamic positioning system. The dynamic positioning system of T/S NARA is applied to K-POS dynamic positioning system of Kongsberg, which makes maintaining the ship's position, changing position and heading control possible. T/S NARA is not capable of dynamic positioning if one or more propulsive forces are lost with DP Level One. However, it is predicted that dynamic positioning can be achieved even at the time of missing one thrust in a good sea condition. Therefore, we want to analyze the effect of each propulsion on the performance of dynamic position system. When one of the bow thruster and azimuth thrusters lost their propulsion, maintaining the ship's position, changing position and heading control performance were compared and analyzed. If the situation occurred disable from using the bow thruster, they can not maintain ship's position. Azimuth thruster was influential for the ship's position control and bow thruster was influential in heading control. The excellent dynamic positioning performance can be achieved, considering the propulsion power that will have a impact on each situation in the future.

• Ocean Systems Engineering
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• v.6 no.3
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• pp.265-287
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• 2016

The change of the global performance of a turret-moored FPSO (Floating Production Storage Offloading) with DP (Dynamic Positioning) control is simulated, analyzed, and compared for two different internal turret location cases; bow and midship. Both collinear and non-collinear 100-yr GOM (Gulf of Mexico) storm environments and three cases (mooring-only, with DP position control, with DP position+heading control) are considered. The horizontal trajectory, 6DOF (degree of freedom) motions, fairlead mooring and riser tension, and fuel consumptions are compared. The PID (Proportional-Integral-Derivative) controller based on LQR (linear quadratic regulator) theory and the thrust-allocation algorithm which is based on the penalty optimization theory are implemented in the fully-coupled time-domain hull-mooring-riser-DP simulation program. Both in collinear and non-collinear 100-yr WWC (wind-wave-current) environments, the advantage of mid-ship turret is demonstrated by the significant reduction in heave at the turret location due to the minimal coupling with pitch mode, which is beneficial to mooring and riser design. However, in the non-collinear WWC environment, the mid-turret case exhibits unfavorable weathervaning characteristics, which can be reduced by employing DP position and heading controls as demonstrated in the present case studies. The present study also reveals the plausible cause of the failure of mid-turret Gryphon Alpha FPSO in milder environment than its survival condition.

• Korean Journal of Agricultural Science
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• v.10 no.1
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• pp.84-89
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• 1983

This study was attempted to find out the most effective period and dosage for IBP granules application to control rice blast, especially neck blast. The results obtained from the study are as follows; The most effective application period was about 15-20 days before heading. The most effective dosage was 4kg per 10a. The most effective control on rice blast was obtained when 4kg per 10a of IBP granules was applied about 15 to 20 days before heading. Therefore it should be emphasized that application period and dosage should be considered together, when applied by farmers. However, it may be necessary to apply chemicals at least one or two times before or after rice heading, since applications of IBP Ec. in July and IBP granules in August may not be enough to control rice blast completely.

• Research in Plant Disease
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• v.9 no.2
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• pp.68-71
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• 2003

Correlation between rice yield loss and infection time of neck blast after panicle emergence was analyzed in paddy fields at Icheon in 1999 and 2000. As the neck blast occurred at early heading stage, the yield loss of a early maturity variety, Jinmibyeo, ranged from 83.9% to 81.6%, while it ranged from 44.3% to 33.1% when the disease developed 30 days after heading. The regression equations of yield loss(y) caused by the neck blast infection time(x) in Jinmibyeo were y =1.2717x + 79.523(R2 = 0.9487) and y = 1.6872x + 74.545(R2 = 0.7993) in 1999 and 2000. In a mid-lately maturity variety, Chucheongbyeo, yield loss ranged from 64.9% to 47.8% when the disease developed at early heading stage. While it ranged from 29.1% to 8.9% when the disease occurred 40 days after heading. The regression equations of yield loss caused by the disease in Chucheongbyeo were y= 1.2717x + 79.523($R^2$ = 0.9487) and y = 1.6872x + 74.545(($R^2$ = 0.7993) in 1999 and 2000. Weights of 1,000 rice grains of Jinmibyeo and Chucheongbyeo were also drastically decreased to 38.3% and 57.3%, respectively, compared to healthy control when the disease occurred at early heading stage. However, weights of the two cultivars were 87.6% and 92.9% compared to control when the disease developed after 40 days of heading. Results indicated that there is a highly negative correlation between rice yield loss and infection time of the neck blast.

• Journal of the Korean Society for Library and Information Science
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• v.46 no.2
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• pp.157-174
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• 2012

This study tries to describe personal name access point control ontology for the American novelist Mark Twain using RDF/OWL axiom to control access point based on the ontology. The Axiom used in this study are disjoint with class, domain and range, property cardinality, inverse functional property, individual and literal data property. As a result, in the ontology environment we can accept various access points as equal access points exclusive of authority heading and heading concept. It can successfully describe Mark Twain's personal name access point control ontology and display using the OntoGraf.