• Journal of Institute of Control, Robotics and Systems
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• v.12 no.9
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• pp.898-904
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• 2006

Ionospheric storms, caused by the interaction between Solar and geomagnetic activities, may degrade the differential GNSS(Global Navigation Satellite Systems) performance significantly, and the importance of the ionospheric storm research is growing for the GBAS(Ground-Based Augmentation System) and SBAS(Satellite-Based Augmentation System) development. In order to support Korean GNSS augmentation system development, a software tool for analyzing the regional ionosphere is being developed and its preliminary results are discussed. After brief description of the ionosphere and ionospheric storm, the research topics on the GBAS applications are discussed. The need for ionospheric spatial gradient analysis is described and some results on the ionospheric spatial gradient during recent storm periods are discussed.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.782-787
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• 2023

Korea augmentation satellite system (KASS) integration, verification, qualification (IVQ) activity is verification of requirements for KASS system and its sub-system that were performed based on the inspection, analysis, review of design, test (IART) method from factory acceptance test (FAT) to test readiness review (TRR) after critical design review (CDR) was closed. In the FAT phase, developed equipment was installed on the test platform and we were verified interfaces between sub-systems and coupling test with the kass control station (KCS). In the site aceeptance test (SAT) phase, on-site verification was conducted by installing equipment verified by FAT such as kass reference station (KRS), kass processing station (KPS), kass uplink station (KUS), KCS. However, considering the developed plan and status, SAT was divided into 3 phases and coupling test was performed. In the TRR phase, the KASS system verification was performed through FAT's test list and additional test list using the satellite based augmentation system (SBAS) broadcast signal from geostationary earth orbit (GEO) 1.

• International Journal of Control, Automation, and Systems
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• v.6 no.1
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• pp.135-141
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• 2008

A new approach to $H_{\infty}$ multi-step prediction is developed by applying the innovation analysis theory. Although the predictor is derived by resorting to state augmentation, nevertheless, it is completely different from the previous works with state augmentation. The augmented state here is considered just as a theoretical mathematic tool for deriving the estimator. A distributed algorithm for the Riccati equation of the augmented system is presented. By using the reorganized innovation analysis, calculation of the estimator does not require any augmentation. A numerical example demonstrates the effect in reducing computing burden.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.72-77
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• 2017

The Satellite Based Augmentation System (SBAS) broadcasts to users integrity and correction information for Global Navigation Satellite System (GNSS) such as GPS and GLONASS using geostationary orbit (GEO) satellites. In accordance with the recommendation of the International Civilian Aeronautical Organization (ICAO) to introduce SBAS until 2025, a Korean SBAS system development / construction project is underway with the Ministry of Land, Transport and Maritime Affairs. Korea Augmentation Satellite System (KASS) is a high precision GPS correction system which is composed of KASS Reference Station (KRS), KASS Processing Station (KPS), KASS Uplink Station (KUS), KASS Control Station (KCS) and GEO satellites. In this paper, we provided the conceptual design of the KASS uplink station, which is composed of the Signal Generator Section (SGS) and the Radio-Frequency Section (RFS), and interface between the KASS ground sector and the GEO satellite.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.54.6-54
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• 2002

1. Introduction 2. The Netwoked Control System Description 2.1 A close-loop system with the network induced delay 2.2 Discretization and State Augmentation of NCS 3. Delay-dependent H_infinity Controller Design for NCS 4. Numerical Example 5. Conclusion

• International Journal of Automotive Technology
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• v.6 no.5
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• pp.545-554
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• 2005

Passive velocity field control (PVFC) was previously developed for fully mechanical systems, in which the motion task was specified by behaviors in terms of a velocity field and the closed-loop was passive with respect to the supply rate given by the environment input. However, the PVFC was only applied to a single manipulator. The proposed control law was derived geometrically and the geometric and robustness properties of the closed-loop system were also analyzed. In this paper, we propose a virtual passivity-based algorithm to apply decentralized control to multiple 3­wheeled mobile robotic systems whose subsystems are under nonholonomic constraints and convey a common rigid object in a horizontal plain. Moreover, it is shown that multiple robot systems ensure stability and the velocities of augmented systems converge to a scaled multiple of each desired velocity field for cooperative mobile robot systems. Finally, the application of proposed virtual passivity-based decentralized algorithm via system augmentation is applied to trace a circle and the simulation results is presented in order to show effectiveness for the decentralized control algorithm proposed in this research.

• International Journal of Control, Automation, and Systems
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• v.5 no.1
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• pp.104-109
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• 2007

This paper is about a redundancy management system design for the Smart UAV(unmanned aerial vehicle) which utilizes the tilt..rotor mechanism. In order to meet the safety requirement on the PLOC(probability of loss of control) of $1.7{\times}10^{-5}$ per flight hour for FCS (flight control system) failures, a digital FCS is mechanized with a dual redundant structure. A fault detection system which is composed of a CCM(cross channel monitor) and analytic redundancy using the Kalman filtering is designed, and its effectiveness is evaluated through experiments. A threshold level and persistence count for managing redundant sensors are designed based on the statistical analysis of the FCS sensors. To increase the survivability of the UAV after the loss of critical sensors in the SAS(stability augmentation system) and to provide reference information for a tie-breaking condition at which an ILM(in-line monitor) cannot distinguish the faulty channel between two operating ones, the Kalman filter approach is investigated.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.50-55
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• 2017

In this paper, the design of the RF system monitoring and control system of KUS (KASS: KASS Uplink Station) which constitutes KASS (Korea Augmentation Satellite System) is described. The Korean satellite calibration system is named KASS and aims to develop the SBAS system of the APV-1 level SoL service level and the CAT-1 test operation technology. Software and hardware development environment, function and algorithm of supervisory control device, structure of supervisory control device, and user interface were designed to implement KUS / RFS monitoring control device. We have secured the stability and reliability of the system by using the monitoring and control system design of the COMS (Communication Ocean & Meteorological Satellite) and the Korea Satellite 5A / 7 control system, which has already been used for the design of the surveillance control system. In addition, we have made it possible to provide the user interface according to the actual operator's request more conveniently.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.2 s.152
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• pp.180-188
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• 2007

In this paper the longitudinal control problem for the large WIG(wing-in-ground effect) craft is considered in the sense of the control augmentation system(CAS) derived by control surface of elevator. In order to achieve longitudinally stable systems, two modes of CAS are applied to the control systems which are pitch rate hold mode and pitch hold mode for steady flight. Since the employed CASs include the dynamic properties of the actuator time delay and the low pass filter, it provides the possible solution to be applicable to real systems. Nonlinear model simulations are fulfilled to investigate the effectiveness of the applied CASs with wind disturbance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.7
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• pp.35-44
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• 2006

When control surface failure occurs, it is conventional to correct a current control or to transform to other control. In this paper, instead of adopting a conventional way, a reconfiguration method which compensate the failure with alternative control surface deflection, depending on the level of failure, by using neural network and PCH(Pseudo-Control Hedging). The Conroller is designed of inner-loop(SCAS : Stability Command Augmentation System) with DMI(Dynamic Model Inversion) and outer-loop with Y axis acceleration feedback for a coordinate turn. Additionally, double PCH method was adopted to prevent actuator saturation and input command was generated to compensate for failure. At the end, The feasibility of the method is validated with randomly selected failure scenarios.