Browsing by Author "Liang, Yew-Wen"

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A Guidance Law Design Using the Combination of ISMC and SDRE Schemes
(2013)
Liang, Yew-Wen
;
Chen, Jun-Yu
;
Lin, Li-Gang
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper studies the design of a robust guidance law for missiles in the presence of uncertainties, which may include inaccurate prediction of target maneuver. Under the design, the closed-loop guidance system is shown to be robust to the uncertainties. Additionally, the scheme presented possesses the flexibility of allowing the engineer to select a desired guidance law for the nominal system (i.e., system without uncertainty) so that the state response of the overall uncertain guidance system is close to that of the selected nominal closed-loop guidance system. The simulation results demonstrate the benefits of the presented scheme.
A higher-order stabilizability condition for a class of switched systems
(2006)
Liang, Yew-Wen
;
Xu, Sheng-Dong
;
Chiang, Chia-Chen
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This study investigates the existence of stabilizing switching rules among a class of unstable nonlinear systems. A high-order checking condition and an associated stabilizing switching rule are presented to implement the stabilizability of the switched systems. An illustrative example is also given to demonstrate the usage and the benefits of the proposed scheme.
A Robust Guidance Law with Predictable Performance
(2013-01-01)
Liang, Yew-Wen
;
Chen, Jun-Yu
;
Jhu, Wei-Ming
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper deals with the design of a robust guidance law for missiles in the presence of unknown target maneuver. Under the design, the closed-loop guidance system is shown to be robust to the target maneuver. Additionally, the scheme presented possesses the flexibility of allowing the engineer to select a desired guidance law for the nominal system (i.e., system without target maneuver) so that the state response of the overall uncertain guidance system is close to that of the selected nominal closed-loop guidance system. The simulation results clearly demonstrate the benefits of the presented scheme.
A Study of T-S Model-Based SMC Scheme With Application to Robot Control
(2008-11-01)
Liang, Yew-Wen
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Xu, Sheng-Dong
;
Liaw, Der-Cherng
;
Chen, Cheng-Chang
;
電控工程研究所
In light of the remarkable benefits and numerous applications of the Takagi-Sugeno (T-S) fuzzy system modeling method and the sliding mode control (SMC) technique, this paper aims to study the design of robust controllers for a set of second-order systems using a combination of these two approaches. The combined scheme is shown to have the merits of both approaches. It alleviates not only the online computational burden by using the T-S fuzzy system model to approximate the original nonlinear one (since most of the system parameters of the T-S model can be computed offline) but also preserves the advantages of rapid response and robustness characteristic of the classic SMC schemes. Moreover, the combined scheme does not need to online compute any nonlinear term of the original dynamics, and the increase in the number of fuzzy rules does not create extra online computational burdens for the scheme. The proposed analytical results are also applied to the control of a two-link robot manipulator and compared with the results using classic SMC design. Simulation results demonstrate the benefits of the proposed scheme.
Analysis of SDC matrices for successfully implementing the SDRE scheme
(2013-10-01)
Liang, Yew-Wen
;
Lin, Li-Gang
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The state-dependent Riccati equation (SORE) approach for stabilization of nonlinear affine systems was recently reported to be effective in many practical applications; however, there is no guideline on the construction of state-dependent coefficient (SDC) matrix when the SDRE solvability condition is violated, which may result in the SDRE scheme being terminated. In this study, we present several easy checking conditions so that the SORE scheme can be successfully implemented. Additionally, when the presented checking conditions are satisfied, the sets of all feasible SDC matrices and their structures are explicitly depicted for the planar system. (C) 2013 Elsevier Ltd. All rights reserved.
Analytical representation of the state-dependent coefficients in the SDRE/SDDRE scheme for multivariable systems
(2015-09-01)
Lin, Li-Gang
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Vandewalle, Joos
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Liang, Yew-Wen
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電控工程研究所
;
Institute of Electrical and Control Engineering
Recently, the easy-to-implement state-dependent Riccati equation (SDRE) strategy has been shown effective for numerous practical applications. Since being similar to SDRE, the newly emerged state-dependent differential Riccati equation (SDDRE) approach shares most of the benefits of SORE, and exhibits interesting potential from both the analytical and practical viewpoints. By generalizing previous works to the general-order nonlinear time-variant systems, we try to resolve several problems related to the design flexibility (the infinitely many candidates of the state-dependent coefficient matrix), since they appear at the beginning of the implementation of both schemes. Finally, we demonstrate the proposed scheme via examples. (C) 2015 Elsevier Ltd. All rights reserved.
Common stabilizers for linear control systems in the presence of actuators outage
(2006-06-15)
Liang, Yew-Wen
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Liaw, Der-Cherng
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Issue concerning the existence of common stabilizers for a linear control system experiences actuators. outage are presented. The possible outage of actuators examined in this study are not restricted to a pre-specified set. By finding Common quadratic-type Lyapunov functions. we obtain sufficient conditions for the existence of common stabilizers. For cases of which all the possible failed actuators belonged to a pre-specified set. the results presented in this paper agree with those obtained by Veillette in 1995. The control gain of common stabilizer for non-nested case is explicitly derived to guarantee system stability. A simplified checking condition for the existence of common stabilizers is also obtained for the extreme case when only single actuator can normally operate. (c) 2005 Elsevier Inc. All rights reserved.
Construction of stabilizing switching laws among unstable linear systems
(2006)
Liang, Yew-Wen
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Xu, Sheng-Dong
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Chang, Jia-Liang
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Chiang, Chia-Chen
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電控工程研究所
Issues concerning the construction of quadratically stabilizing switching laws among N unstable linear systems are studied in this paper. The obtained results are also employed to study the existence of control laws and quadratically stabilizing switching laws among a class of unstabilizable linear control systems. Finally, the illustrative examples and simulation results show the feasibility and effectiveness of the proposed methods.
CONTROL FOR A CLASS OF SECOND-ORDER SYSTEMS VIA A STATE-DEPENDENT RICCATI EQUATION APPROACH
(2018-01-01)
Lin, Li-Gang
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Liang, Yew-Wen
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Cheng, Li-Jen
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This study investigates the state-dependent Riccati equation (SDRE) controller for a class of second-order nonlinear systems. By fully exploiting the design degree of freedom (DOF) arising from the nonunique state-dependent coefficient (SDC) matrices, we explicitly calculate the ranges of control input via the SDRE scheme. Moreover, when a permissible control input is determined, we also explicitly parameterize the SDC matrices that result in the designated control value, in terms of system states and parameters, so the engineer can easily implement the scheme. Notably, this is the first analytical result that explores the range of control input using the design DOF of SDC matrices. In addition, by applying the analytical results, it is shown that the second order systems are always globally stabilizable, without any supplementary assumptions on weighting matrices (as extended from existing SDRE global results), and the corresponding stabilizing SDC matrices are also explicitly presented. Finally, illustrative examples clearly demonstrate the benefits of the analytical results.
Convex Quadratic Equation
(2020-09-01)
Lin, Li-Gang
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Liang, Yew-Wen
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Hsieh, Wen-Yuan
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電控工程研究所
;
Institute of Electrical and Control Engineering
Two main results (A) and (B) are presented in algebraic closed forms. (A) Regarding the convex quadratic equation, an analytical equivalent solvability condition and parameterization of all solutions are formulated, for the first time in the literature and in a unified framework. The philosophy is based on the matrix algebra, while facilitated by a novel equivalence/coordinate transformation (with respect to the much more challenging case of rank-deficient Hessian matrix). In addition, the parameter-solution bijection is verified. From the perspective via (A), a major application is re-examined that accounts for the other main result (B), which deals with both the infinite and finite-time horizon nonlinear optimal control. By virtue of (A), the underlying convex quadratic equations associated with the Hamilton-Jacobi equation, Hamilton-Jacobi inequality, and Hamilton-Jacobi-Bellman equation are explicitly solved, respectively. Therefore, the long quest for the constituent of the optimal controller, gradient of the associated value function, can be captured in each solution set. Moving forward, a preliminary to exactly locate the optimality using the state-dependent (resp., differential) Riccati equation scheme is prepared for the remaining symmetry condition.
Decentralized stabilization of neural network linearly interconnected systems via T-S fuzzy control
(2007-05-01)
Hsiao, Feng-Hsiag
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Liang, Yew-Wen
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Xu, Sheng-Dong
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Lee, Gwo-Chuan
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電控工程研究所
The stabilization problem is considered in this study for a neural-network (NN) linearly interconnected system that consists of a number of NN models. First, a linear difference inclusion (LDI) state-space representation is established for the dynamics of each NN model. Then, based on the LDI state-space representation, a stability criterion in terms of Lyapunovs direct method is derived to guarantee the asymptotic stability of closed-loop NN linearly interconnected systems. Subsequently, according to this criterion and the decentralized control.scheme, a set of Takagi-Sugeno (T-S) fuzzy controllers is synthesized to stabilize the NN linearly interconnected system.. Finally, a numerical example with simulations is given to demonstrate the concepts discussed throughout this paper.
Design of Midcourse Guidance Laws via a Combination of Fuzzy and SMC Approaches
(2010-04-01)
Chen, Chun-Hone
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Liang, Yew-Wen
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Liaw, Der-Cherng
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Chang, Shih-Tse
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Xu, Sheng-Dong
Issues regarding the design of midcourse guidance laws for antimissiles are addressed. The antimissile is expected to be guided to a place with a desired direction, where a ballistic missile is predicted to pass in the reverse direction, so that the target can be easily found and locked for terminal interception. The predicted location and direction of a ballistic missile may vary with time, due to information update using a trajectory prediction algorithm. To fulfill the guidance performance, the guidance laws are designed by combining the Takagi-Sugeno (T-S) fuzzy approach and the Sliding Mode Control (SMC) technique. Under the designed guidance law, it is shown that the antimissile is able to be efficiently guided to a specified location and direction, even when the existence of uncertainties and disturbances.
Design of Robustly Asymptotic Stabilizer Using a Time-Varying Sigmoid-Type SMC Scheme
(2008)
Liang, Yew-Wen
;
Xu, Sheng-Dong
;
Cheng, Chiz-Chung
;
Liaw, Der-Cherng
;
電控工程研究所
This study presents a class of first-order sliding mode stabilizing control laws, which preserve the advantages of rapid response and robustness from the conventional sliding mode control (SMC) schemes. The presented SMC laws are continuous everywhere so that the chaffering characteristic of the sign-type SMC laws is greatly alleviated. This scheme is also shown to be able to mend the saturation-type SMC's weakness of only achieving uniformly ultimate boundedness performance to an asymptotic stability level.
Fault Tolerant Control of Nonlinear Systems Via a CA-Based Integral Sliding Mode Technique
(2013-01-01)
Chen, Chih-Chiang
;
Liang, Yew-Wen
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper explores the active fault tolerant control issue for a class of uncertain nonlinear systems using a control allocation (CA)-based integral sliding mode control (ISMC) technique. When the information of fault detection and diagnosis is available, the presented scheme can tolerate some of the actuators\' faults, while maintains the main advantages of both CA and ISMC techniques. A remarkable one is that, when the uncertainties and/or disturbances are matched, the state trajectories of the selected nominal system and the uncertain faulty system are identical. As a result, engineers can predictively address the performance of matched uncertain faulty system in accordance with the performance of a selected nominal system. The proposed analytic results are applied to the attitude control of a spacecraft to demonstrate the benefits of the proposed scheme.
Global Output Feedback Stabilization of a Class of Nonlinear Systems With Unknown Measurement Sensitivity
(2018-07-01)
Chen, Chih-Chiang
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Qian, Chunjiang
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Sun, Zong-Yao
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Liang, Yew-Wen
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電控工程研究所
This note investigates the problem of global output feedback stabilization for a class of nonlinear systems with unknown measurement sensitivity. A new design method, namely dual-domination approach, is proposed to explicitly construct a state observer as well as an output feedback control law, which globally asymptotically stabilizes the nonlinear systems. The novelty of this note owes to a distinct perspective in coping with unknown measurement sensitivity which has previously been a hurdle to solve the global output feedback stabilization problem of the nonlinear systems.
Global Stability of a System with State-Dependent Riccati Equation Controller
(2015-10-01)
Chen, Chih-Chiang
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Liang, Yew-Wen
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Jhu, Wei-Ming
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電控工程研究所
;
Institute of Electrical and Control Engineering
Interval homogeneous domination approach for global stabilization of nonlinear systems with time-varying powers
(2016-01-01)
Chen, Chih-Chiang
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Qian, Chunjiang
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Liang, Yew-Wen
;
Li, Shihua
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電控工程研究所
This paper considers the problem of global stabilization for a class of nonlinear systems with time-varying powers. A new design method based on the technique of adding a power integrator and the interval homogeneous domination approach, which can be thought as an evolution of the homogeneous domination approach, is developed to explicitly construct a smooth state feedback globally stabilizing controller. The novelty of this paper is the development of a systematic scheme, which provides us a new perspective to deal with the state feedback control problem for the nonlinear systems with time varying powers.
Nonlinear Reliable Control With Application to a Vehicle Antilock Brake System
(2013-11-01)
Liang, Yew-Wen
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Chen, Chih-Chiang
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Liaw, Der-Cherng
;
Wei, Yuan-Tin
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電控工程研究所
This paper explores the design of active reliable control systems for a class of uncertain nonlinear affine systems using an integral-type sliding mode control (ISMC) scheme. The presented scheme not only maintains the main advantages of the ISMC design, including robustness, rapid response and easy implementation, but it can also tolerate some actuator faults when fault detection and diagnosis information is available. In this study, the uncertainties and/or disturbances are not required to be of the matched type; however, when they are matched, the state trajectories of the nominal healthy subsystem and the uncertain faulty system are identical. As a result, engineers can predictively address the matched uncertain faulty system performance in light of the performance of the nominal healthy subsystem. The analytic results are also applied to the study of a vehicle brake reliable control system. Simulation results demonstrate the benefits of the proposed scheme.
Reliable control of nonlinear systems via variable structure scheme
(2006-10-01)
Liang, Yew-Wen
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Xu, Sheng-Dong
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This study proposes a class of variable structure stabilizing laws which make the closed-loop system be capable of tolerating the abnormal operation of actuators within a pre-specified subset of actuators. The ranges of acceptable change in control gain magnitude that preserves system's stability are estimated for the whole set of actuators. These ranges are shown to be able to be made larger than those obtained by linear quadratic regulator (LQR) reliable design (Veillette, 1995, and Liang et al, 2000) by the choice of control parameters. Besides, this approach doesnot need the solution of Hamilton-Jacobi (HJ) equation or inequality, which is essential for optimal approaches such as LQR and H-infinity reliable designs. As a matter of fact, this approach can also relax the computational burden for solving the HJ equation or inequality.
Robust control of the robot manipulator via an improved sliding mode scheme
(2007)
Liang, Yew-Wen
;
Xu, Sheng-Dong
;
Chu, Tzu-Chiang
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電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, an improved Sliding Mode Control (SMC) scheme, reformed from the conventional SMC approaches, is developed for position tracking of a robot manipulator with parameter uncertainties and external disturbances. The improved SMC scheme, which uses saturation-type SMC laws, is shown to be able to surpass the level of uniformly ultimate boundedness to achieve asymptotic stability. In addition, the presented first-order SMC laws are continuous; as a result, this scheme can also alleviate the undesirable chattering behavior that is characteristic of sign-type SMC laws. Simulation results demonstrate the benefits of the proposed scheme.