The Experts below are selected from a list of 137007 Experts worldwide ranked by ideXlab platform
Fang Wang - One of the best experts on this subject based on the ideXlab platform.
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nonlinear robust control for reusable launch vehicles in reentry phase based on time varying high order sliding mode
Journal of The Franklin Institute-engineering and Applied Mathematics, 2013Co-Authors: Bailing Tian, Qun Zong, Jie Wang, Fang WangAbstract:Abstract This paper describes the design of nonlinear robust controller for reusable launch vehicles which is nonlinear, multivariable, strong coupling, and includes uncertain parameters. Firstly, the feasible guidance strategy is proposed to obtain the desired guidance commands. Then, the time-varying sliding mode manifold is designed through calculating a series of algebraic equations with fixed final states to make the System trajectories start on the manifold at the initial time. The global robustness is ensured via designing high order sliding mode attitude controller which forces the System Trajectory to stay on the sliding mode manifold despite the model parameter uncertainties and external disturbances. Furthermore, in order to reduce control saltation, the virtual control is introduced into the control strategy. Finally, the six degree of freedom flight simulation results are provided to demonstrate the effectiveness of the integrated guidance and control strategy in tracking the guidance commands as well as achieving safe and stable reentry flight.
C K Tang - One of the best experts on this subject based on the ideXlab platform.
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hybrid transient stability analysis power Systems
IEEE Transactions on Power Systems, 1990Co-Authors: G A Maria, C K TangAbstract:The hybrid method of power System transient stability analysis, which combines the desirable features of both the time-domain simulation technique and the direct method of transient stability analysis, is presented. The hybrid method first computes the actual System Trajectory using time-domain simulation, then evaluates the transient energy function in order to derive a stability index for fast derivation of transient stability limits. Proper criteria are proposed to stop the time-domain simulation of the System Trajectory to reduce CPU time, once the status of the System has been identified. The method was successfully applied to three test Systems varying in size from four generators to 50 generators. The method is shown to be a potential tool for online calculation of transient stability limits. >
T Van Cutsem - One of the best experts on this subject based on the ideXlab platform.
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wide area detection of voltage instability from synchronized phasor measurements part i principle
IEEE Transactions on Power Systems, 2009Co-Authors: Mevludin Glavic, T Van CutsemAbstract:This two-part paper deals with the early detection of an impending voltage instability from the System states provided by synchronized phasor measurements. Recognizing that voltage instability detection requires assessing a multidimensional System, the method fits a set of algebraic equations to the sampled states, and performs an efficient sensitivity computation in order to identify when a combination of load powers has passed through a maximum. The important effects of overexcitation limiters are accounted for. The approach does not require any load model. This first part of the paper is devoted to theoretical foundations of sensitivity calculation along the System Trajectory, derivation of the algebraic model, and illustration on a simple five-bus System involving the long-term dynamics of a load tap changer and a field current limiter.
Bailing Tian - One of the best experts on this subject based on the ideXlab platform.
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nonlinear robust control for reusable launch vehicles in reentry phase based on time varying high order sliding mode
Journal of The Franklin Institute-engineering and Applied Mathematics, 2013Co-Authors: Bailing Tian, Qun Zong, Jie Wang, Fang WangAbstract:Abstract This paper describes the design of nonlinear robust controller for reusable launch vehicles which is nonlinear, multivariable, strong coupling, and includes uncertain parameters. Firstly, the feasible guidance strategy is proposed to obtain the desired guidance commands. Then, the time-varying sliding mode manifold is designed through calculating a series of algebraic equations with fixed final states to make the System trajectories start on the manifold at the initial time. The global robustness is ensured via designing high order sliding mode attitude controller which forces the System Trajectory to stay on the sliding mode manifold despite the model parameter uncertainties and external disturbances. Furthermore, in order to reduce control saltation, the virtual control is introduced into the control strategy. Finally, the six degree of freedom flight simulation results are provided to demonstrate the effectiveness of the integrated guidance and control strategy in tracking the guidance commands as well as achieving safe and stable reentry flight.
Keith Burnham - One of the best experts on this subject based on the ideXlab platform.
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Embedding-Based Sliding Mode Control for Linear Time Varying Systems
Applied Mathematics, 2011Co-Authors: Mohammad Reza Zarrabi, Mohammad Hadi Farahi, Sohrab Effati, A. Jafari Koshkouei, Keith BurnhamAbstract:In this paper, a novel strategy using embedding process and sliding surface is proposed. In this method, a state Trajectory starting from a given initial point reaches a definite point on a sliding surface in the minimum time, and then tends to the origin along the sliding surface (SS). In the first, a SS is designed, then using an appropriate measure, an embedding is constructed to solve a time optimal control problem such that the System Trajectory reaches the SS in minimum time, after that a control is designed such that the System Trajectory tends to the origin along the SS. It is well-known that the main disadvantage of the use of sliding mode controls (SMCs) is a phenomenon, the so-called chattering. The proposed SMC here is piecewise continuous and chattering free. Some numerical examples is presented to illustrate the effectiveness and reliability of the proposed method
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Almost optimal sliding mode control for linear time varying Systems
UKACC International Conference on Control 2010, 2010Co-Authors: Mohammad Hadi Farahi, Sohrab Effati, A. Jafari Koshkouei, Keith BurnhamAbstract:This paper presents a new sliding mode control (SMC) design approach using embedding process based on measure theory. In this method, a state Trajectory starting from a given initial point reaches a definite point on a sliding surface in the minimum finite time, and then tends to the origin along the sliding surface (SS). A measure theory approach with embedding process is used to solve such a problem in two phases. In the first phase, using an appropriate measure, an embedding is constructed to solve a time optimal control problem such that the System Trajectory reaches the SS in minimum time, and in the second phase, using measure theory, a control is designed such that the System Trajectory tends to the origin along the SS. The proposed SMC is piecewise continuous and chattering free.
