• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.7
• /
• pp.75-84
• /
• 2003

To reduce the effects of the uncertainties due to the modeling error and aerodynamic coefficients, a nonlinear adaptive control system based on neural networks is proposed . Neural networks parameters are adjusted by using an adaptive law. The sliding mode control scheme is used to compensate for the effect of the approximation error of neural networks. Control parameters and neural networks structures are optimized to obtain better performance by using the genetic algorithm. By introducing the concept of multi-groups of populations, the genetic algorithm is modified so that individuals and groups can be simultaneously evolved . To verify the performance of the pro posed algorithm, the optimized neural networks control system is applied to an aircraft longitudinal dynamics.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.4
• /
• pp.25-32
• /
• 2006

An advanced method of Relaxed Static Stability (RSS) is utilized for improving the aerodynamic performance of modern version supersonic jet fighter aircraft. The flight control system utilize 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 longitudinal two modes are the short period with high frequency and the phugoid mode with low frequency. The design goals of longitudinal control laws is concerned with the short period damping and frequency optimization using lower order equivalent system and utilizing the requirement of MIL-F-8785C. Analysis of short period mode has been and continues to be performed This paper addresses the analysis of aircraft phugoid node characteristics such as damping, natural frequency, and analysis of aircraft pitch motion that impacted by angle of attack limiter and auto pitch attitude control law.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.1 no.1
• /
• pp.166-188
• /
• 1998

본 논문에서는 쿼터니온 궤환 개념이 기존의 오일러각 궤환 개념에 비해 추력벡터제어(Thrust Vector Control) 방식을 사용하는 전술 유도탄 자세제어에 보다 효과적으로 적용될 수 있음을 보인다. 오일러각 궤환 방식을 택한 기존의 자세제어기에서 오일러각 궤환 부분을 쿼터니온 궤환으로 적절히 바꾸어 주게 되면 자세명령 크기 변화에 따른 시간응답 특성의 변화를 줄일 수 있으며, 쿼터니온 궤환 방식을 택할 경우, 우주비행체 자세제어 분야에서 활발히 연구되고 있는 고유축(Eigen Axis) 회전에 의한 자세변환을 수행할 수 있는 자세제어기 설계가 가능하다. 고유축 회전은 최단경로에 의한 자세변환 개념이므로, 이러한 능력을 갖춘 자세제어기는 신속한 자세변환이 필요한 전술 유도탄의 초기비행에 매우 효과적으로 이용될 수 있다. 더욱이, 제어법칙에 공력모멘트를 보상하는 항을 추가하게 되면 변화가 심한 공력 모멘트가 유도탄의 회전운동에 미치는 영향을 줄일 수 있어 고유축 회전성능을 보다 개선시킬 수 있다. 우선, 오일러각 궤환보다 쿼터니온 궤환이 유리한 점을 논하고, 쿼터니온 궤환에 근거한 자세제어기의 설계 개념과 제안된 제어기에 의해 구성되는 폐루우프에 대한 안정성 문제를 다룬 후, 시뮬레이션을 통해 그 타당성을 검증한다.

• Current Industrial and Technological Trends in Aerospace
• /
• v.7 no.2
• /
• pp.85-94
• /
• 2009

The Fly-By-Wire system was first applied to the fighter and its inherent advantages lead to the advent of the Fly-By-Wire civil aircraft. Recently even the small jet aircraft shows the trend of adopting the Fly-By-Wire system. In the future, most of the aircraft are expected to be the Fly-By-Wire type. In this paper, the structure and the characteristics of the Fly-By-Wire system applied to the civil aircraft was described. The development trend of the redundant method of the flight control system, data communication system, control surface actuation system and the control laws implemented by the Fly-By-Wire system of the civil aircraft are discussed.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.18 no.3
• /
• pp.509-520
• /
• 2023

In this paper, the structure and the characteristics of the Fly-By-Wire system applied to the civil aircraft was described. The development trend of the redundant method of the flight control system, data communication system, control surface actuation system and the control laws implemented by the Fly-By-Wire system of the civil aircraft are discussed. The Fly-By-Wire system was first applied to the fighter and its inherent advantages lead to the advent of the Fly-By-Wire civil aircraft. Recently even the small jet aircraft shows the trend of adopting the Fly-By-Wire system. In the future, most of the aircraft are expected to be the Fly-By-Wire type.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.10
• /
• pp.842-850
• /
• 2014

This paper presents a trajectory tracking controller for rotorcraft UAVs to improve the tracking performances in the presence of various uncertainties. The proposed tracking method consists of a velocity guidance law based on the relative distance and L1 adaptive augmentation loop for tracking the velocity commands. In the proposed structure, the desired velocity generated by the guidance law is the reference value of the adaptive controller for accurate path tracking. In the guidance law, the desired acceleration is generated based on the relative distance and its derivatives, and then the velocity command of the inner control loop is calculated by integrating the accelerations. $L_1$ augmentation loop supplements the linear controller to guarantee the flight performances such as a tracking accuracy in the presence of the uncertainties. The proposed controller was validated in actual flight tests to successfully demonstrate its capability using a quadrotor UAV.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.2
• /
• pp.162-169
• /
• 2011

The flight control system utilize RSS(Relaxed Static Stability) criteria in both longitudinal axes to achieve performance enhancements and improve stability. The aircraft using digital flight-by-wire flight control system receives aircraft flight conditions such as pitch, roll and yaw rate, normal acceleration from RSA(Rate Sensor Assembly) and ASA(Acceleration Sensor Assembly). These sensors has permissible measurement error related to system safety of an aircraft but, unexpected flight motions are happened by sensing errors such as offset, noise and etc. The unexpected pitch down tendency occurred by ASA sensor bias in 1g level flight with pilot hands-off. This paper addresses the design and verification of flight control law to improve of pitch down or up tendency caused by ASA sensor bias. The result of analysis and flight test reveals that pitch down tendency can be improved by pitch attitude feedback system.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.3
• /
• pp.228-235
• /
• 2010

This paper deals with an autonomous flight controller design problem for a tilt-rotor aircraft in rotary-wing mode. The inner-loop algorithm is designed using the output-based approximate feedback linearization. The model error originated from the feedback linearization is cancelled within allowable tolerance by using single-hidden-layer neural network. According to Lyapunov direct stability theory, the adaptive update law is derived to run the neural network on-line, which is based on the linear observer dynamics. Moreover, the outer-loop algorithm is designed to track the trajectory generated from way-point guidance. Especially, heading and flight-path angle line-of-sight guidance are applied to the outer-loop to improve accuracy of the landing tracking performance. The 6-DOF nonlinear simulation shows that the overall performance of the flight control algorithm is satisfactory even though the collective input response shows instantaneous actuator saturation for a short time due to the lack of the neural network and the saturation protection logic in that loop.

• Aerospace Engineering and Technology
• /
• v.2 no.1
• /
• pp.11-21
• /
• 2003

This paper deals with preliminary design results of autopilot for station keeping mode of airship. Linear equations of motion for the airship are derived. Basic architecture of the control laws for cruising and station keeping modes are proposed. Performance analysis results show that autopilot design for station keeping mode of airship is feasible.

• Communications of the Korean Institute of Information Scientists and Engineers
• /
• v.30 no.9
• /
• pp.37-45
• /
• 2012