• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.40.1-40
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• 2002

1. Introduction 2. Vehicle Equations of Motion 3. Discrete Model of the Plant with an Unmodeled Dynamics 4. Design of an Adaptive Control 5. Parameter Adjustment Law 6. Numerical Simulations 7. Summary

• International Journal of Aeronautical and Space Sciences
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• v.8 no.1
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• pp.21-31
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• 2007

Relaxed Static Stability (RSS) concept has been applied to improve aerodynamic performance of modern version supersonic jet fighter aircraft. The T-50 advanced supersonic trainer employs the RSS concept in order to improve the aerodynamic performance. And the flight control system stabilizes the unstable aircraft and provides adequate handling qualities. The T-50 longitudinal control laws employ a proportional-plus-integral type controller based on a dynamic inversion method. The longitudinal dynamic modes consist of short period with high frequency and phugoid mode with low frequency. The design goal of longitudinal control law is optimization of short period damping ratio and frequency using Lower Order Equivalent System (LOES) complying the requirement of MIL-F-8785C. This paper addresses phugoid mode characteristics such as damping ratio and natural frequency that is affected by the nonlinear control laws such as angle of attack limiter, auto pitch attitude command system and autopilot of pitch attitude hold.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.11
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• pp.963-969
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• 2005

An advanced method of Relaxed Static Stability (RSS) is utilized for improving the aerodynamic performance of modem version supersonic jet fighter aircraft. The flight control system utilizes RSS criteria in both longitudinal and lateral-directional axes to achieve performance enhancements and improve stability. The T-50 advanced trainer employs the RSS concept in order to improve the aerodynamic performance and the flight control law in order to guarantee aircraft stability, The T-50 longitudinal control laws employ the dynamic inversion and proportional-plus-integral control method. This paper details the design process of developing longitudinal control laws for the RSS aircraft, utilizing the requirement of MIL-F-8785C. In addition, This paper addresses the analysis of aircraft characteristics such as damping, natural frequency, gain and phase margin about state variables for longitudinal inner loop feedback design.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.12
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• pp.1302-1312
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• 2008

Relaxed Static Stability(RSS) has been applied to improve flight performance of modern version supersonic jet fighters. Flight control systems are necessary to stabilize an unstable aircraft and to provide adequate handling qualities. Also, flight control systems of modern aircraft employ many safety measure to cope with emergency situations such as a pilot unknown attitude flight conditions of an aircraft in night flight-testing. This situation is dangerous because the aircraft can lose if the pilot not take recognizance of situation. The system called the "Pilot Activated Recovery System" or PARS, provided a pilot initiated automatic maneuver capable of an aircraft recoveries in situations of unusual attitudes, speed and altitude. This paper addresses the concept of PARS with AARS(Automatic Attitude Recovery System), ATCS(Automatic Thrust Control System) and MARES(Minimum Altitude Recovery Estimation System), and this control law is designed by nonlinear control law design process based on model of supersonic jet trainer. And, this control law is verified by real-time pilot evaluation using an HQS(Handling Quality Simulator). The result of evaluation reveals that the these systems support recovery of an aircraft unusual attitude and speed, and improve a safety of an aircraft.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.6
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• pp.1026-1030
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• 2011

This paper presented here contains development of variable stability system(VSS) control laws for the KIFS (Korean In-Flight Simulator) aircraft to simulate the dynamics of F-16 aircraft. Development of VSS Control law for pitch rate, roll rate, yaw rate simulation for three specified flight conditions using Model Following Technique with rate feedback autopilot for stability provision. The direct lift force controller was also added to the developed VSS control law to simulate the pitch rate and normal g-load simultaneously. The simulation results show high accuracy of F-16 aircraft's pitch, roll, yaw rate and g-load simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.8
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• pp.669-676
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• 2015

In this paper, a guidance law for intercepting maneuvering target with a desired impact angle is proposed. The proposed guidance law is modified from the optimal impact angle control law for a fixed target and given by a biased PN law with the impact angle control term in addition to the conventional PN law. Three different kinds of desired impact angles in the respect of LOS angle, flight path angle, and relative flight path angle to the target are defined. The performance of the proposed guidance law is investigated via numerical simulations for various air-to-air engagement scenarios.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.522-534
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• 2017

According to the characteristics of salvo attack for the multiple flight vehicles (MFV), the design of cooperative guidance law can be converted into the consensus problem of multi-vehicle system through the concept of multi-agent cooperative control. The flight vehicles can be divided into leader and followers depending on different functions, and the flight conditions of leader are independent of the ones of followers. The consensus problem of leader-follower multi-vehicle system is researched by graph theory, and the consensus protocol is also presented. Meanwhile, the finite time guidance law is designed for the flight vehicles via the finite time control method, and the system stability is also analyzed. Whereby, the guidance law can guarantee the line of sight (LOS) angular rates converge to zero in finite time, and hence the cooperative attack of the MFV can be realized. The effectiveness of the designed cooperative guidance method is validated through the simulation with a stationary target and a moving target, respectively.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.12
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• pp.1244-1252
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• 2008

This paper presents the analysis results obtained by the flight test of reconfiguration flight control system for an aircraft. The reconfiguration flight control system was designed by using control allocation scheme that automatically distributes the demanded control moments determined by control law to each actual control surface. In this paper, some control allocation algorithms for reconfiguration control of general aircraft with redundant control surfaces are summarized and their performance evaluation results through nonlinear simulation and Hardware-In-the-Loop-Simulation (HILS) test are shown. Also, Unmanned Aerial Vehicle (UAV) system adopted as a platform for the flight test of reconfiguration flight controller and the implementation procedure of reconfiguration flight controller into real-time UAV system were introduced. Finally, flight test results were analyzed.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1647-1650
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• 1997

This paper presents the control law of Automatic Rudder Trim System(ARTS) for the KTX-1. The proposed ARTS is designed mainly t reduce the pilot's work load for trimming in the various conditiions of engine torque. airspeed, and aircraft configuration. The ARTS partially compensates the transient yawing motion due to change of engine power in turboprop aircraft because of the limitation of the actuation speed of the trim motor. In this paper flight test data are analyzed to understand the phenomena and the dynamics of the reversible rudder flight control system is derived. Finally, the control concept and conrtol law of ARTS are described and the characteristics of the ARTS are analyzed through simulation study.

• Journal of Aerospace System Engineering
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• v.9 no.1
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• pp.12-18
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• 2015

The inter-conversion between different control laws in flight has a lot of risk. The SWM(Switching Mechanism) including logic and stand-by mode is designed to analyze the transient response of aircraft during inter-conversion between different control laws, based on the in-house software for non-real-time and real-time simulation. The SWM applies the fader logic of TFS(Transient Free Switch) to minimize the transient response of an aircraft during the inter-conversion, and applies the reset '0' type of the stand-by mode to prevent surface saturation due to integrator effect in the disengaged flight control law. The transition time is also important to minimize the objectionable transient response in the inter-conversion, as well as the transition control law design. This paper addresses the results of non-real-time simulation for the characteristics of transient response to different transition time to select the adequate transient time, and the real-time pilot evaluation, using SSWM(Software Switching Mechanism) and HSWM(Hardware Switching Mechanism), which is met for Level 1 flying qualities and assures safety of flight.