Absolute stability and integral control for infinite-dimensional discrete-time systems (2009)
Coughlan, J J, Logemann, Hartmut
We derive absolute stability results of Popov and circle-criterion types for infinite-dimensional discrete-time systems in an input-output setting. Our results apply to feedback systems in which the...
Adaptive sampled-data integral control of stable infinite-dimensional linear systems (2009)
Ke, Z Q, Logemann, Hartmut, Townley, S.
In this paper, adaptive discrete-time low-gain integral control strategies are presented for tracking constant reference signals for infinite-dimensional discrete-time power-stable linear systems....
Jayawardhana, B., Logemann, Hartmut, Ryan, Eugene P
Input-to-state stability (ISS) of a class of differential inclusions is proved. Every system in the class is of Lur'e type: a feedback interconnection of a linear system and a set-valued...
Ke, Z. Q., Logemann, Hartmut, Rebarber, R.
In this paper we solve tracking and disturbance rejection problems for stable infinite-dimensional systems using a simple low-gain controller suggested by the internal model principle. For stable...
A Sampled-Data Servomechanism for Stable Well-Posed Systems (2009)
Ke, Z, Logemann, Hartmut, Rebarber, R.
In this technical note, an approximate tracking and disturbance rejection problem is solved for the class of exponentially stable well-posed infinite-dimensional systems by invoking a simple...
Indirect sampled-data control with sampling period adaptation (2008)
Ilchmann, Achim, Ke, Zhenqing, Logemann, Hartmut
Preprint / Technische Universität Ilmenau, Institut für Mathematik ; 08-22
GENERALIZED SAMPLED-DATA STABILIZATION OF WELL-POSED LINEAR INFINITE-DIMENSIONAL SYSTEMS ∗ (2008)
Hartmut Logemann, Richard Rebarber, Stuart Townley
Abstract. We consider well-posed linear infinite-dimensional systems, the outputs of which are sampled in a generalized sense using a suitable weighting function. Under certain natural assumptions on...
Stability of infinite-dimensional sampled-data systems, preprint (2008)
Hartmut Logemann, Richard Rebarber, Stuart Townley, Hilbert Spaces
Abstract. Suppose that a static-state feedback stabilizes a continuous-time linear infinite-dimensional control system. We consider the following question: if we construct a sampled-data controller...
Hartmut Logemann, Claverton Down, Bath Ba Ay, Richard Rebarber
Abstract: In this paper we consider a large class of partial differential equations (PDEs) with distributed control and with a time-delay in the feedback loop. We analyze the relationship between the...
Ruth F. Curtain, Hartmut Logemann, Stuart Townley, Hans Zwart
The object of this paper is to further develop the theory of Pritchard-Salamon systems, which are abstract infinite-dimensional systems allowing for a certain unboundedness of the control and...
Destabilizing Effects of Small Time-Delays on Feedback Controlled Descriptor Systems (2007)
Hartmut Logemann, Claverton Down, Bath Ba Ay
: In the last 15 years the problems of stabilizability and stabilization of descriptor systems have received considerable attention. In this paper it will be shown that if the open-loop system...
Adaptive Lambda-Tracking for a Class of Infinite-Dimensional Systems (2007)
Achim Ilchmann, Exeter Ex Qe, Hartmut Logemann, Claverton Down, Bath Ba Ay
: For a class of high-gain stabilizable multivariable linear infinite-dimensional systems we present an adaptive control law which achieves approximate asymptotic tracking in the sense that the...
Hartmut Logemann, Bath Ba Ay, Richard Rebarber, Stuart Townley
Abstract: Suppose that a static state feedback stabilizes a continuous-time linear innite-dimensional control system. We consider the following question: if we construct a sampled-data controller by...
Hartmut Logemann, Stuart Townley
Abstract: It is well-known that if the steady-state gain G(0) of a stable lumped system, with transfer function G(s), is positive, then compensating the system by an integral controller k=s, where k...
Hartmut Logemann, Richard Rebarber, George Weiss
Abstract: It has been observed that for many stable feedback control systems, the introduction of arbitrarily small time delays into the loop causes instability. In this paper we present a systematic...
Hartmut Logemann, Stuart Townley
Abstract: It is well-known that closing the loop around an exponentially stable, finite-dimensional, linear, time-invariant plant with square transfer-function matrix G(s) compensated by a controller...
Adaptive Low-Gain Integral Control of Multivariable Well-Posed Linear Systems (2007)
Hartmut Logemann, Stuart TOWNLEY
The principle of low-gain integral control for nite-dimensional systems is wellknown. More recently, low-gain integral control results have been obtained for classes of in nitedimensional systems. In...
Hartmut Logemann, Eugene P Ryan
This paper, which has a tutorial flavour, develops a self-contained, elementary and unified approach to a variety of results (including LaSalle's Invariance Principle and generalizations...
Tracking with prescribed transient performance for hysteretic systems (2007)
Ilchmann, Achim, Logemann, Hartmut, Ryan, Eugene P.
Preprint / Technische Universität Ilmenau, Institut für Mathematik ; 07-01
The Z-transform and linear multistep stability (2007)
Coughlan, James J., Hill, Adrian T., Logemann, Hartmut
This paper makes systematic use of control-theoretic methods such as the 𝒵-transform, small-gain theorems and frequency-domain stability criteria in the analysis of the stability behaviour of...
The {Zscript}-transform and linear multistep stability (2006)
Coughlan, James J., Hill, Adrian T., Logemann, Hartmut
This paper makes systematic use of control-theoretic methods such as the {Zscript}-transform, small-gain theorems and frequency-domain stability criteria in the analysis of the stability behaviour of...
Adaptive λ-[lambda]-tracking for a class of infinite-dimensional systems (2005)
Ilchmann, Achim, Logemann, Hartmut
For a class of high-gain stabilizable multivariable linear infinite-dimensional systems we present an adaptive control law which achieves approximate asymptotic tracking in the sense that the...
High-gain adaptive stabilization of multivariable linear systems - revisited (2005)
Ilchmann, Achim, Logemann, Hartmut
We consider the class of multi-input multi-output, finite dimensional, state space systems of the form x=Ax+Bu. Y, where the state dimension is unknown, the system is minumum phase, and it is known...
An adaptive servomechanism for a class of infinite-dimensional systems (2005)
Ilchmann, Achim, Logemann, Hartmut
A universal adaptive controller is constructed that achieves asymptotic tracking of a given class of reference signals and asymptotic rejection of a prescribed set of disturbance signals for a class...
Discrete-Time Low-Gain Control of Uncertain Infinite-Dimensional Systems (1997)
Hartmut Logemann, Stuart TOWNLEY
: Using a frequency-domain analysis, it is shown that the application of a feedback controller of the form k=(z \Gamma 1) or kz=(z \Gamma 1), where k 2 R, to a power-stable infinite-dimensional...
Adaptive control of infinite-dimensional systems without parameter estimation: an overview (1997)
LOGEMANN, HARTMUT, TOWNLEY, STUART
This paper contains an overview of adaptive control of infinite-dimensional systems without parameter estimation or identification. We describe the main problems and present the most comprehensive...
The Effect of Small Delays in the Feedback Loop on the Stability of Neutral Systems (1995)
Hartmut Logemann, Stuart Townley
: It is well-known that exponential stabilization of a neutral system with unstable difference operator is only possible by allowing for control laws containing derivative feedback. We show that...
Hartmut Logemann, Claverton Down, Bath Ba Ay, Richard Rebarber
: It has been observed that for many stable feedback systems, the introduction of arbitrarily small time delays into the loop causes instability. In this paper we present a systematic treatment of...
Stability and stabilizability of linear infinite-dimensional discrete-time systems (1992)
This paper contains three results on stability and stabilizability of linear time invariant infinite-dimensional discrete-time systems. (1) Power stability is characterized in transfer-function terms...
Robust High-gain Feedback Control of Infinite-Dimensional Minimum-Phase Systems (1987)
LOGEMANN, HARTMUT, OWENS, DAVID H.
This paper deals with a certain class of infinite-dimensional minimum-phase systems. We show that these systems can be stabilized by multivariable PT-controllers with sufficiently high gains; it...
In this paper we study the feedback interconnection (a) of two neutral systems and (b) of two Volterra integrodifferential systems. We show that under very mild assumptions the closed-loop system...