Browsing by Author "Song, CC"

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Analysis of longitudinal flight dynamics: A bifurcation-theoretic approach
(2001-01-01)
Liaw, DC
;
Song, CC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Bifurcation theory has been used to study the nonlinear dynamics and stability of many modern aircraft, especially in broad angle-of-attack flight dynamics. However, the main application of bifurcation analysis is based on numerical simulations to predict and explain the nonlinear instability of flight dynamics by the use of parametric continuation methods. Bifurcation theory is applied to theoretically analyze the nonlinear phenomena of longitudinal flight dynamics, by the choice of the elevator deflection and mass of the aircraft as system parameters. Both stationary and Hopf bifurcations may appear at some critical values of elevator command. Discontinuity also may occur at system equilibria as system parameters vary. The bifurcation phenomena occurring in nonlinear aircraft dynamics might result in jump behaviors, pitch oscillations, or system instabilities. Numerical study of a simple third-order model of longitudinal dynamics verifies the theoretical analysis. Qualitative results are obtained to understand the longitudinal flight dynamics.
Bifurcation analysis of power systems with tap changer
(2005)
Liaw, DC
;
Fang, KH
;
Song, CC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A bifurcation analysis of nonlinear dynamics for electric power system with tap changer is presented in this paper. Based on a model of electric power system proposed by Dobson and Chiang (1988) with one extra tap changer added parallel to the local nonlinear power load, the saddle-node bifurcation and Hopf bifurcations are observed by treating the real power, reactive power and tap changer as system parameters. The occurrences of subcritical Hopf bifurcation and saddle-node bifurcation lead to the appearance of dynamic and static voltage collapses, respectively. These phenomena may generate the progressive decrease in voltage magnitude in electric power system.
Nonlinear control of longitudinal flight dynamics
(2003)
Liaw, DC
;
Song, CC
;
Chung, WC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents the nonlinear analysis and control of a third-order model for longitudinal flight dynamics. Bifurcation analysis using numerical study for F-8 aircraft reveals that Hopf bifurcations may occur at some critical values of the elevator commands. These results agree with the well-known nonlinear phenomena existed in longitudinal flight dynamics. Furthermore, bifurcation control using both washout filter and direct state feedback are applied to develop the stabilizing laws for system equilibria and periodic solutions emerged from bifurcation points. Numerical simulations are provided to demonstrate these main results.
Robust stabilization of a centrifugal compressor with spool dynamic's
(2002)
Liaw, DC
;
Song, CC
;
Huang, JT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Issues. of global stabilization of a centrifugal compressor with spool dynamics are presented. Control schemes are designed for systems with and without system uncertainty. While actuating only the close-coupled valve or the throttle as the single control input, backstepping tools axe first used to achieve global stability of the working equilibrium for systems without uncertainty. The uncertainties in the spool dynamics and the compressor characteristic are known to be likely to happen in practical applications. Under such circumstances, the compressor torque and the close-coupled valve are then employed to achieve robust global stability of the working equilibrium via the Lyapunov redesign method. Numerical simulations are given to demonstrate the main results.
Robust stabilization of a centrifugal compressor with spool dynamics
(2004-11-01)
Liaw, DC
;
Song, CC
;
Huang, JT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Issues of global stabilization of a centrifugal compressor with spool dynamics are presented. Control schemes are designed for systems with and without system uncertainty. While activating only the close-coupled valve or the throttle as the single control input, backstepping tools are first used to achieve global stability of the working equilibrium for systems without uncertainty. The uncertainties in the spool dynamics and the compressor characteristic are known to be likely to happen in practical applications. Under such circumstances, the compressor torque and the close-coupled valve are then employed to achieve robust global stability of the working equilibrium via the Lyapunov redesign method. Numerical simulations are given to demonstrate the main results.
Two-parameter bifurcation analysis of longitudinal flight dynamics
(2003-07-01)
Liaw, DC
;
Song, CC
;
Liang, YW
;
Chung, WC
;
電控工程研究所
The bifurcation analysis of longitudinal flight dynamics is presented, emphasizing the influence of elevator deflection and aircraft mass. Based on a mathematical model proposed by Garrard and Jordan (1977), a rich variety of bifurcation phenomena such as saddle-node bifurcation, Hopf bifurcation, and cycle fold bifurcations are observed in the numerical simulations of longitudinal flight dynamics of the F-8 aircraft. The occurrence of saddle-node bifurcation and Hopf bifurcation may result in jump behavior and pitch oscillations of flight dynamics. The analysis leads to a division of the longitudinal flight space into several maneuvering regions, and may provide more understanding of the longitudinal flight dynamics.