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 Title
 Remarks on stability analysis for delayed systems with applications.
 Creator
 Tiwari, Shanaz, Wang, Yuan, Graduate College
 Date Issued
 20110408
 PURL
 http://purl.flvc.org/fcla/dt/3164800
 Subject Headings
 Nonlinear control theory, Lyapunov functions, Time delay systems
 Format
 Document (PDF)
 Title
 A Robust Converse Lyapunov Theorem for Systems with Disturbances Taking Values in a Banach Space.
 Creator
 Gallolu Kankanamalage, Hasala Senpathy, Wang, Yuan, Graduate College
 Abstract/Description

This paper presents a converse Lyapunov theorem for robust global asymptotic stability. The main result extends previous converse Lyapunov theorems to systems with disturbances taking bounded values in an arbitrary Banach space.
 Date Issued
 2015
 PURL
 http://purl.flvc.org/fau/fd/FA00005878
 Format
 Document (PDF)
 Title
 Nonlinear control of underactuated horizontal double pendulum.
 Creator
 Popescu, Cristian., Florida Atlantic University, Wang, Yuan, Roth, Zvi S.
 Abstract/Description

Underactuated mechanical systems are those possessing fewer actuators than degrees of freedom, making the class a rich one from a control standpoint. The double inverted pendulum is a particular underactuated system and a wellknown benchmark case for which many solutions have been offered in the literature. The control objective is to bring the system to its unstable top equilibrium point. The underactuated horizontal double pendulum is a twolink planar robot with only one actuator either...
Show moreUnderactuated mechanical systems are those possessing fewer actuators than degrees of freedom, making the class a rich one from a control standpoint. The double inverted pendulum is a particular underactuated system and a wellknown benchmark case for which many solutions have been offered in the literature. The control objective is to bring the system to its unstable top equilibrium point. The underactuated horizontal double pendulum is a twolink planar robot with only one actuator either at the shoulder or the elbow. Almost no work was done on the underactuated horizontal pendulum, mainly due to the lack of controllability of such a system. The fundamental difference between a double inverted pendulum and an underactuated horizontal double pendulum is that in the latter gravity effects do not exist. Gravity is important to the controllability of the system. Thus, in search for a "gravity substitute," we added springs in the underactuated horizontal double pendulum in order to create a source of potential energy. Two different types of such systems are analyzed: spring coupled underactuated horizontal double pendulums and underactuated horizontal double pendulums with springloaded sliding bar constraint. The main contribution of the thesis is in proving that the zero state of the spring coupled systems is globally asymptotically stabilizable. Explicit control laws were developed.
Show less  Date Issued
 2002
 PURL
 http://purl.flvc.org/fcla/dt/12894
 Subject Headings
 Double pendulums, Nonlinear control theory
 Format
 Document (PDF)
 Title
 Inputtostate stability properties for discretetime nonlinear systems.
 Creator
 Gao, Kehan, Florida Atlantic University, Wang, Yuan, Charles E. Schmidt College of Science, Department of Mathematical Sciences
 Abstract/Description

In this thesis, we study the inputtostate stability (scISS) property and related characterizations for discretetime nonlinear systems. Variations of scISS property were employed in solving particular control problems. The main contribution of this work is to provide a detailed analysis on the relations among various types of notations related to system stability and show that most scISS results for continuoustime nonlinear system can be extended to discretetime case.
 Date Issued
 1999
 PURL
 http://purl.flvc.org/fcla/dt/15688
 Subject Headings
 Discretetime systems, Nonlinear systems, Stability, Control theory
 Format
 Document (PDF)
 Title
 Stability analysis for singularly perturbed systems with timedelays.
 Creator
 Yang, Yang, Wang, Yuan, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Mathematical Sciences
 Abstract/Description

Singularly perturbed systems with or without delays commonly appear in mathematical modeling of physical and chemical processes, engineering applications, and increasingly, in mathematical biology. There has been intensive work for singularly perturbed systems, yet most of the work so far focused on systems without delays. In this thesis, we provide a new set of tools for the stability analysis for singularly perturbed control systems with time delays.
 Date Issued
 2015
 PURL
 http://purl.flvc.org/fau/fd/FA00004423, http://purl.flvc.org/fau/fd/FA00004423
 Subject Headings
 Biology  Mathematical models, Biomathematics, Differentiable dynamical systems, Differential equations, Partial  Numerical solutions, Global analysis (Mathematics), Lyapunov functions, Nonlinear theories
 Format
 Document (PDF)
 Title
 Output Stability Analysis for Nonlinear Systems with Time Delays.
 Creator
 Gallolu Kankanamalage, Hasala Senpathy, Wang, Yuan, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Mathematical Sciences
 Abstract/Description

Systems with time delays have a broad range of applications not only in control systems but also in many other disciplines such as mathematical biology, financial economics, etc. The time delays cause more complex behaviours of the systems. It requires more sophisticated analysis due to the infinite dimensional structure of the space spaces. In this thesis we investigate stability properties associated with output functions of delay systems. Our primary target is the equivalent Lyapunov...
Show moreSystems with time delays have a broad range of applications not only in control systems but also in many other disciplines such as mathematical biology, financial economics, etc. The time delays cause more complex behaviours of the systems. It requires more sophisticated analysis due to the infinite dimensional structure of the space spaces. In this thesis we investigate stability properties associated with output functions of delay systems. Our primary target is the equivalent Lyapunov characterization of inputtooutput stability (ios). A main approach used in this work is the Lyapuno Krasovskii functional method. The Lyapunov characterization of the so called outputLagrange stability is technically the backbone of this work, as it induces a Lyapunov description for all the other output stability properties, in particular for ios. In the study, we consider two types of output functions. The first type is defined in between Banach spaces, whereas the second type is defined between Euclidean spaces. The Lyapunov characterization for the first type of output maps provides equivalence between the stability properties and the existence of the LyapunovKrasovskii functionals. On the other hand, as a special case of the first type, the second type output renders flexible Lyapunov descriptions that are more efficient in applications. In the special case when the output variables represent the complete collection of the state variables, our Lyapunov work lead to Lyapunov characterizations of iss, complementing the current iss theory with some novel results. We also aim at understanding how output stability are affected by the initial data and the external signals. Since the output variables are in general not a full collection of the state variables, the overshoots and decay properties may be affected in different ways by the initial data of either the state variables or just only the output variables. Accordingly, there are different ways of defining notions on output stability, making them mathematically precisely. After presenting the definitions, we explore the connections of these notions. Understanding the relation among the notions is not only mathematically necessary, it also provides guidelines in system control and design.
Show less  Date Issued
 2017
 PURL
 http://purl.flvc.org/fau/fd/FA00004935, http://purl.flvc.org/fau/fd/FA00004935
 Subject Headings
 Nonlinear systems., Time delay systems., Multiagent systems., Adaptive control systems., Chaotic behavior in systems.
 Format
 Document (PDF)
 Title
 INTEGRAL INPUTTOOUTPUT STABILITY ANALYSIS FOR NONLINEAR SYSTEMS WITH TIME DELAYS.
 Creator
 Nawarathna, R. H. Harsha, Wang, Yuan, Florida Atlantic University, Department of Mathematical Sciences, Charles E. Schmidt College of Science
 Abstract/Description

One of the central issues in stability analysis for control systems is how robust a stability property is when external disturbances are presented. This is even more critical when a system is affected by time delay. Systems affected by time delays are ubiquitous in applications. Time delays add more challenges to the task of stability analysis, mainly due to the fact that the state space of a delay system is not a finitedimensional Euclidean space anymore, but rather an infinite dimensional...
Show moreOne of the central issues in stability analysis for control systems is how robust a stability property is when external disturbances are presented. This is even more critical when a system is affected by time delay. Systems affected by time delays are ubiquitous in applications. Time delays add more challenges to the task of stability analysis, mainly due to the fact that the state space of a delay system is not a finitedimensional Euclidean space anymore, but rather an infinite dimensional space of continuous functions defined on the delay interval. In this work, we investigate robust output stability properties for nonlinear systems affected by time delays and external disturbances. Frequently in applications, the requirement of stability properties imposed on the full set of state variables can be too strenuous or even unrealistic. This motivates one to consider robust output stability properties which are related to partial stability analysis in the classic literature. We start by formulating several notions on integral inputtooutput stability and illustrate how these notions are related. We then continue to develop LyapunovKrasovskii type of results for such stability properties. As in the other context of Lyapunov stability analysis such as global asymptotic stability and inputtostate stability, a LyapunovKrasovskii functional is required to have a decay rate proportional to the magnitudes of the state variables or output variables on the whole delayed interval. This is a difficult feature when trying to construct a LyapunovKrasovskii functional. For this issue, we turn our efforts to LyapunovKrasovskii functional with a decay rate depending only on the current values of state variables or output variables. Our results lead to a type of LyapunovKrasovskii functionals that are more flexible regarding the decay rate, thereby leading to more efficient results for applications.
Show less  Date Issued
 2023
 PURL
 http://purl.flvc.org/fau/fd/FA00014267
 Subject Headings
 Nonlinear systems, Time delay systems
 Format
 Document (PDF)
 Title
 A study of Internetbased control of processes.
 Creator
 Popescu, Cristian., Florida Atlantic University, Zhuang, Hanqi, Wang, Yuan, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
 Abstract/Description

In certain applications, one needs to control physical plants that operate in hazardous conditions. In such situations, it is necessary to acquire access to the controller from a different (remote) location through data communication networks, in order to interconnect the remote location and the controller. The use of such network linking between the plant and the controller may introduce network delays, which would affect adversely the performance of the process control. The main theoretical...
Show moreIn certain applications, one needs to control physical plants that operate in hazardous conditions. In such situations, it is necessary to acquire access to the controller from a different (remote) location through data communication networks, in order to interconnect the remote location and the controller. The use of such network linking between the plant and the controller may introduce network delays, which would affect adversely the performance of the process control. The main theoretical contribution of this thesis is to answer the following question: How large can a network delay be tolerated such that the delayed closedloop system is locally asymptotically stable? An explicit timeindependent bound for the delay is derived. In addition, various practical realizations for the remote control tasks are presented, utilizing a set of predefined classes for serial communication, dataacquisition modules and streambased sockets. Due to the presence of a network, implementing an efficient control scheme is a not trivial problem. Hence, two practical frameworks for Internetbased control are illustrated in this thesis. Related implementation issues are addressed in detail. Examples and case studies are provided to demonstrate the effectiveness of the proposal approach.
Show less  Date Issued
 2003
 PURL
 http://purl.flvc.org/fcla/dt/13073
 Subject Headings
 Time delay systems, Process control, Computer networksRemote access, World Wide Web
 Format
 Document (PDF)