Browsing by Author "Liang, YW"

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Application of FIDF to the detection of unstable behaviors in compression systems
(2000)
Liang, YW
;
Liaw, DC
;
Wu, YC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Issues concerning the detection of surge and rotating stall in a compression system are studied in this paper. It is observed that the plenum pressure rise and mass flow rate of a compression system exhibit abrupt change due to the appearance of surge or rotating stall, while those of it's linearized model do not. With this observation, a linear-based fault identification filter (FIDF) design technique is proposed to detect these two instabilities. This is achieved by treating the difference between the output of the compression system and that of its linearized model at an unstalled operating point as a fault vector and then investigating the effect of the fault on the designed FIDF. Simulation results for Moore and Greitzer's compression model [14] are given to demonstrate the effectiveness of the proposed scheme. The study may provide a means of detecting the occurrence of unstable phenomena at the onset so that a corrective action can be made.
Application of VSC reliable design to spacecraft attitude tracking
(2005)
Liang, YW
;
Xu, SD
;
Chu, TC
;
Cheng, CC
;
Liaw, DC
This study investigates variable structure reliable control issues of nonlinear systems and its applications to spacecraft attitude tracking problems. The proposed passive reliable control laws must know in advance which group of actuators is allowed to fail. These reliable controllers need not the solution of Hamilton-Jacobi (HJ) equation or inequality that are essentials in optimal approaches such as LQR and Hoo reliable designs. As a matter of fact, this approach is able to relax the computational load in computing the solution of HJ equation. The proposed reliable designs are also applied to spacecraft attitude tracking problems to explain their effectiveness and benefits. Finally, simulation results and comparisons between LQR and Variable Structure Control (VSC) reliable designs are presented to illustrate the merits of the proposed scheme. Although the proposed design is a passive one, it may provide a guideline for active design when a Fault Detection and Diagnosis (FDD) scheme is available.
Asymptotic stabilization of driftless systems
(1999-02-15)
Liaw, DC
;
Liang, YW
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Issues of asymptotic stabilization of a class of non-linear driftless systems are presented. In addition to the necessary and sufficient condition for the existence of a smooth time-invariant asymptotic stabilizer, sufficient condition for the existence of a quadratic-type Lyapunov function candidate is also proposed herein to alleviate the construction of stabilizing control laws. Following the deduction of the equivalence of the sufficient condition and the determination of the local definiteness of a defined scalar function, the stabilizability checking conditions are then derived in terms of system dynamics and its derivatives at the origin only. These are achieved by taking Taylor's series expansion on system dynamics. The derived conditions are shown to be consistent with those obtained by Brockett. Comparative results of Liaw and Liang are also included. Finally, examples are given to demonstrate the use of the main results.
Detection of surge and stall in compression systems: An example study
(2001-10-01)
Liang, YW
;
Liaw, DC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Issues concerning the detection of surge and rotating stall in a compression system are considered. It is observed that, when surge or rotating stall happens, the plenum pressure rise and mass flow rate of a compression system exhibit abrupt change while those of its linearized model do not. With this observation, it is shown that the surge and rotating stall can be successfully detected by employing a linear-based fault identification filter (FIDF) design technique. This is achieved by treating the difference between the output of the compression system and that of its linearized model at an unstalled operating point as a fault vector and then investigating the effect of the fault on the designed FIDE Simulation results with regard to Moore and Greitzer's compression model (1986) are given to demonstrate the effectiveness of the proposed approach. The theoretical study presented in this note may provide a guideline of detecting the occurrence of unstable phenomena at the onset so that corrective responses can be made in the practical applications.
Feedback stabilization of nonlinear driftless systems with applications to homogeneous-type systems
(1997-02-01)
Liaw, DC
;
Liang, YW
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Issues of asymptotic stabilization of nonlinear driftless systems as given by x = g(x)u with applications to homogeneous-type driftless systems are presented. Conditions of the existence of a smooth time-invariant stabilizer for general nonlinear driftless systems are obtained by the construction of quadratic-type Lyapunov functions. The proposed conditions do not contradict Brockett's (1983) result for the existence of a smooth time-invariant stabilizer. These results are then employed to study the stabilization problem of homogeneous-type systems. Sufficient conditions are obtained for the stabilization of planar type homogeneous driftless systems with positive order. It is shown that the single input control driftless systems cannot be asymptotically stabilizable by any continuous control if g(x) is a homogeneous function of even order. Moreover, equivalent conditions for the stabilizability of linear driftless systems and the explicit design of stabilizing control laws for bilinear driftless systems are also presented.
Feedback stabilization of nonlinear driftless systems with applications to homogeneous-type systems
(1997-02-01)
Liaw, DC
;
Liang, YW
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
Issues of asymptotic stabilization of nonlinear driftless systems as given by x = g(x)u with applications to homogeneous-type driftless systems are presented. Conditions of the existence of a smooth time-invariant stabilizer for general nonlinear driftless systems are obtained by the construction of quadratic-type Lyapunov functions. The proposed conditions do not contradict Brockett's (1983) result for the existence of a smooth time-invariant stabilizer. These results are then employed to study the stabilization problem of homogeneous-type systems. Sufficient conditions are obtained for the stabilization of planar type homogeneous driftless systems with positive order. It is shown that the single input control driftless systems cannot be asymptotically stabilizable by any continuous control if g(x) is a homogeneous function of even order. Moreover, equivalent conditions for the stabilizability of linear driftless systems and the explicit design of stabilizing control laws for bilinear driftless systems are also presented.
Nonlinear control for missile terminal guidance
(2000-12-01)
Liaw, DC
;
Liang, YW
;
Cheng, CC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Variable Structure Control (VSC) technique is applied to the design of robust homing missile guidance laws. In the design procedure, the target's maneuver is assumed to be unpredictable and is considered as disturbances. Guidance laws are then proposed to achieve the interception performance for both cases of longitude-axis control being available and unavailable. The proposed guidance laws are continuous which alleviate chattering drawback by classic VSC design. Results are obtained and compared with those by realistic true proportional navigation design to illustrate the benefits of the proposed decision. [S0022-0434(00)00604-3].
On asymptotic stabilization of driftless systems
(2000-09-11)
Liang, YW
;
Liaw, DC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A simple approach is proposed to investigate the stabilization of driftless systems. By taking the control input as a function of system states, we can transform the stabilization design into a stability problem. The known stability results on the nonlinear autonomous system are then employed to derive the asymptotically stabilizing controllers by solving an algebraic equation. Existence conditions of the asymptotic stabilizing feedback controller for the driftless systems by employing the stability criteria on linear systems and a class of third-order homogeneous systems are obtained to demonstrate the application of the approach. (C) 2000 Elsevier Science Inc. All rights reserved.
On existence and construction of stabilizing switching laws between two unstable linear systems
(2005)
Liang, YW
;
Tan, YH
;
Xu, SD
;
Chang, JL
;
電控工程研究所
Issues regarding the application of two equivalent sufficient conditions for the existence of stabilizing switching laws between two unstable linear systems are studied. One of the conditions is effective for theoretical derivation, while the other is easily implementable. To further understand the geometrical insight of the conditions, an equivalent condition involving the information of eigenvalues and eigenvectors of system dynamics is presented for planar cases. With the help of the equivalent relation, a condition for the existence of controllers and stabilizing switching laws between two unstabilizable linear control systems is also presented. The controllers and stabilizing switching laws are explicitly constructed through the use of an existed algorithm.
Quadratic polynomial solutions of the Hamilton-Jacobi inequality in reliable control design
(1998-09-01)
Liaw, DC
;
Liang, YW
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In the design of nonlinear reliable controllers, one major issue is to solve for the solutions of the Hamilton-Jacobi inequality. In general, it is hard to obtain a closed form solutions due to the nonlinear nature of the inequality. In this paper, we seek for the existence conditions of quadratic type positive semidefinite solutions of Hamilton-Jacobi inequality. This is achieved by taking Taylor's series expansion of system dynamics and investigating the negative definiteness of the associated Hamilton up to fourth order. An algorithm is proposed to seek for possible solutions. The candidate of solution is firstly determined from the associated algebraic Riccati inequality. The solution is then obtained from the candidate which makes the the truncated fourth order polynomial of the inequality to be locally negative definite. Existence conditions of the solution are explicitly attained for the cases of which system linearization possesses one uncontrollable zero eigenvalue and a pair of pure imaginary uncontrollable eigenvalues. An example is given to demonstrate the application to reliable control design problem.
Reliable control of nonlinear systems
(2000-04-01)
Liang, YW
;
Liaw, DC
;
Lee, TC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, we extend Veillette's results (1995) to the study of reliable linear-quadratic regulator problem for nonlinear systems. This is achieved by employing the Hamilton-Jacobi inequality in the nonlinear case instead of algebraic Riccati equation in the linear one. The proposed state-feedback controllers are shown to be able to tolerate the outage of actuators within a prespecified subset of actuators. Both the pain margins of guaranteeing system stability and retaining a performance bound are estimated.
Reliable control of nonlinear systems via variable structure scheme
(2003)
Liang, YW
;
Chu, TC
;
Liaw, DC
;
Cheng, CC
;
電控工程研究所
This study proposes a class of reliable Variable Structure Control (VSC) laws, which are shown to be able to tolerate the outage of actuators within a prespecified subset of actuators. The gain margins of guaranteeing system stability are estimated, which depend on control parameters and are larger than those obtained by LQR reliable design (Veillette, 1995 and Liang et. al., 2000). In addition, this approach does not need to solve the Hamilton-Jacobi equation or inequality, which is known difficult to solve and is an essential part in the reliable LQR and H-infinity designs. As a matter of fact, this approach can also relax the computational load for solving the Hamilton-Jacobi inequality.
Reliable output tracking control for a class of nonlinear systems
(2004-09-01)
Liang, YW
;
Xu, SD
;
Chu, TC
;
Cheng, CC
;
電控工程研究所
This study investigates nonlinear reliable output tracking control issues. Both passive and active reliable control laws are proposed using Variable Structure Control technique. These reliable laws need not the solution of Hamilton-Jacobi (HJ) equation or inequality, which are essential for optimal approaches such as LQR and H-infinity reliable designs. As a matter of fact, this approach is able to relax the computational burden for solving the HJ equation. The proposed reliable designs are also applied to a bank-to-turn missile system to illustrate their benefits.
Robust attitude control for spacecraft
(2002)
Liang, YW
;
Chu, TC
;
Cheng, CC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper, deals with the spacecraft attitude tracking problems in the presence of model uncertainties and external disturbances. A modified VSC design scheme is proposed by the use of Variable Structure Control (VSC) design technique. These modified VSC laws are continuous, which are shown able to alleviate chattering drawback inherited from sign-type VSC controllers and enhance the uniformly ultimate boundedness performance suffered by saturation-type ones to asymptotic stability level. Numerical simulations are also given to demonstrate the benefits of the proposed VSC scheme.
Robust control of non-linear affine systems
(2003-05-25)
Liang, YW
;
Liaw, DC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Issue of robust control for non-linear affine systems with uncertainties appearing in both drift and non-drift terms are presented. Based on Lyapunov function approach, control laws are proposed to guarantee uniformly asymptotic stability of the equilibrium point. To facilitate the design and simplify the checking procedure, stabilization control for the uncertain systems possess asymptotic stabilizable nominal time-invariant driftness terms are proposed for the demonstration of robust design. (C) 2002 Elsevier Science Inc. All rights reserved.
T-S fuzzy controllers for Nonlinear interconnected systems with multiple time delays
(2005-09-01)
Hsiao, FH
;
Chen, CW
;
Liang, YW
;
Xu, SD
;
Chiang, WL
This paper investigates the effectiveness of a passive tuned mass damper (TMD) and fuzzy controller in reducing the structural responses subject to the external force. In general, TMD is good for linear systems. We proposed here an approach of Takagi-Sugeno (T-S) fuzzy controller to deal with the nonlinear system. To overcome the effect of modeling error between nonlinear multiple time-delay systems and T-S fuzzy models, a robustness design of fuzzy control via model-based approach is proposed in this paper. A stability criterion in terms of Lyapunov's direct method is derived to guarantee the stability of nonlinear multiple time-delay interconnected systems. Based on the decentralized control scheme and this criterion, a set of model-based fuzzy controllers is then synthesized via the technique of parallel distributed compensation (PDC) to stabilize the nonlinear multiple time-delay interconnected system and the HI control performance is achieved at the same time. Finally, the proposed methodology is illustrated by an example of a nonlinear TMD system.
Three-dimensional guidance law for landing on a celestial object
(2000-09-01)
Liaw, DC
;
Cheng, CC
;
Liang, YW
;
電控工程研究所
;
Institute of Electrical and Control Engineering
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.
Voltage collapse detection of a power system based on the FIDF technique
(2005)
Liang, YW
;
Liu, HY
;
Xu, SD
;
Lin, SJ
;
電控工程研究所
In this paper, an effective linear-based fault identification filter (FIDF) design technique is applied to voltage collapse detection in a power system so that a corrective action can be made at the onset of unstable phenomena. This is achieved by treating the difference between the load voltage of the power system and that of its linearized model at a stable operating point as a fault vector and then investigating the effect of the fault on the designed FIDE. In practical applications, since FIDF has a low pass filter property and is easily calculated, it can effectively attenuate the influences of high frequency measurement noises and be employed as an on-line detection scheme. Simulation results for Dobson and Chiang's power system model (1990) are finally given to demonstrate the effectiveness of the FIDE design.