KEYWORDS: Control systems design, Control systems, Device simulation, Structural design, Computer programming, Lithium, Instrumentation control, Seaborgium, Computing systems, Process control
Design method of eigenvalue assignment based on standard characteristic polynomial, as well as mathematical solving
process of the method, is proposed in this paper so as to resolve the uncertainty of ideal eigenvalue choice in modern
control theory and the difficultly in engineering implementation of modern control system design methods. Longitudinal
stability holding control system of an aircraft was designed and simulated by employing proposed method. Dynamic
character and robust performance simulation of the system are given. Simulation results show that the method achieves
the control quality and has better robustness than another method. There is only one design parameter which is easy to
calculate. So, the method is characterized as simple design, logical structure, easy programming and convenient for
engineering implementation.
A dynamic decoupling nonlinear control method for MIMO system is presented in this paper. The dynamic inversion
method is used to decouple the multivariable system. The nonlinear control method is used to overcome the poor
decoupling effect when the system model is inaccurate. The nonlinear control method has correcting function and is
expressed in analytic form, it is easy to adjust the parameters of the controller and optimize the design of the control
system. The method is used to design vertical transition mode of active control aircraft for gust alleviation. Simulation
results show that the designed vertical transition mode improves the gust alleviation effect about 34% comparing with
the normal aircraft.
KEYWORDS: Control systems, Systems modeling, Fuzzy logic, Control systems design, Complex systems, Mathematical modeling, Device simulation, Dynamical systems, MATLAB, Automatic control
Dynamic inversion method can not only remove a system's nonlinear factors, but also achieve the system's dynamic
decoupling. But its decoupling effect completely depends on the accuracy of the mathematical model of the system. A
dynamic decoupling fuzzy control method for MIMO system is presented in this paper, which employs the dynamic
inversion method to decouple the multivariable system and introduces a fuzzy controller, without quantification, with
correcting function, and expressed in analytic form to overcome the poor decoupling effect when the system model is
inaccurate. It is feasible and convenient to compute, tune, and realize the control rules by computer, to adjust the
parameters of the controller and to optimize the design of the control system, for the rules are described by analytical
expression. The method is adopted to design vertical transition mode of an active control aircraft for gust alleviation. The
control laws and simulation diagrams of the system are designed. Simulation results in MATLAB show that the vertical
transition mode designed by dynamic decoupling fuzzy control method increases the gust-against effect by about 34%
compared with that of a normal aircraft.
As enlarging of the flight envelop, the aerodynamic derivative of the airplane varies enormous. The gain scheduling
method is usually used to deal with it. But the workload is enormously and the stability is difficulty to be assured. To
solve the above problem, a large envelope wavelet neural network gain scheduling flight control law design method
based on genetic algorithm is presented in this paper. Wavelet has good time accuracy in high frequency-domain and the
good frequency accuracy in low frequency-domain. Neural network has the self-learning character. In this method,
wavelet function instead of Sigmoid function as the excitation function. So the two merits are merged and the high
nonlinear function approximation capability could be achieved. In order to obtain higher accuracy and faster speed,
genetic algorithm is used to optimize the parameters of the wavelet neural network. This method is used in design the
large envelope gain scheduling flight control law. This simulation results show that good control capability could be
achieved in large envelope and the system is still stable when modeling error is 20%. In the situation of 20% modeling
error, the maximum overshoot is only 12m and it is 35% of the maximum overshoot using normal method.
KEYWORDS: Control systems, Control systems design, Error control coding, Device simulation, Motion models, Technetium, Feedback loops, Magnesium, Automatic control, Lithium
Historically, aircraft longitudinal control has been realized by means of two loops: flight path (the control variable is
elevator displacement) and speed control (the control variable is propulsive thrust or engine power). Both the elevator
and throttle control cause coupled altitude and speed response, which exerts negative effects on longitudinal flight
performance of aircraft, especially for Terrain Following(TF) flight. Energy-based method can resolve coupled problem
between flight speed and path by controlling total energy rate and energy distribution rate between elevator and throttle.
In this paper, energy-based control method is applied to design a TF flight control system for controlling flight altitude
directly. An error control method of airspeed and altitude is adopted to eliminate the stable error of the total energy
control system when decoupling control. Pitch loop and pitch rate feedback loop are designed for the system to damp the
oscillatory response produced by TF system. The TF flight control system structure diagram and an aircraft point-mass
energy motion model including basic control loops are given and used to simulate decoupling performance of the TF
fight control system. Simulation results show that the energy-based TF flight control system can decouple flight velocity
and flight path angle, exactly follow planned flight path, and greatly reduce altitude error, which is between +10m and
-8m.
A method for design of flight controllers that provides desired handling qualities over a wide range of flight conditions is presented. The aircraft considered in this paper is capable of flight at very high angles of attack and has thrust vectoring as well as conventional aerodynamic control surfaces. This paper only considers the longitudinal control. The control design method is to use an inner-loop, dynamic inversion controller and an outer-loop, the main-auxiliary fuzzy controller without quantification. The dynamic inversion controller lienarizes the ptich rate dynamcis ofthe aircraft. However, since model uncertainties prevent exact linearization, there will always be errors associated with this controller. The outer-loop fuzzy controller provides robustness to errors due to the lack of exact cancellation of the pitch rate dynamics by the dynamic inversion controller. In addition, its simulation results are also provided.
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