1,720,976 research outputs found
New Results in Singular Linear Quadratic Optimal Control
No full textThis paper focuses on the singular infinite-horizon linear quadratic (LQ) optimal control problem for continuous-time systems. In particular, we are interested in the stabilising impulse-free solutions to this problem that can be expressed as a static state feedback. In particular we establish a link between the geometric properties of the so-called Hamiltonian system associated with the optimal control problem at hand and the so-called proper deflating subspaces of the Hamiltonian matrix pencil
Comments on "Structural Invariant Subspaces of Singular Hamiltonian Systems and Nonrecursive Solutions of Finite-Horizon Optimal Control Problems"
No full textIn this note the paper "Structural Invariant Subspaces of Singular Hamiltonian Systems and Nonrecursive Solutions of Finite-Horizon Optimal Control Problems" is analyzed. It is shown that its main result concerning a characterization of a pair of structural invariant subspaces associated with the extended symplectic system, is a particular case of a result presented in other works within a more general and rigorous context.
We also analyze the proof of the main result of the above mentioned paper, and the way such result is used to accommodate the boundary conditions in the solution of a finite-horizon linear quadratic optimal control problem
On the definition of negative imaginary system for not necessarily rational symmetric transfer functions
Full text linkIn this paper we provide a definition and characterisation of negative imaginary systems for not necessarily rational but symmetric transfer functions along the same lines of the classic definition of positive real systems. We then derive a necessary and sufficient condition that characterises symmetric negative imaginary transfer functions in terms of a matrix sign condition on the imaginary axis
A reduction technique for generalised Riccati difference equations arising in linear-quadratic optimal
Full text linkIn this paper we develop a reduction technique for the generalised Riccati difference equation arising in optimal control and optimal filtering. This technique relies on a decomposition method for the generalised Riccati difference equation that isolates its nilpotent part, which becomes constant in a number of iteration steps equal to the nilpotency index of the closed-loop, from another part that can be computed by iterating a reduced-order Riccati difference equation
The generalised discrete algebraic Riccati equation arising in LQ optimal control problems: Part II
Full text linkIn this paper we develop an analytic approach to the solution of a very general class of discrete finite-horizon optimal control problems. This method hinges on a new decomposition of the so-called extended symplectic pencil. Interestingly, the results established in this paper hold under assumptions that are weaker than the ones considered in the literature so far
Analytical and Graphical Design of Lead-Lag Compensators
No full textIn this paper an approach based on inversion formulae is used for the design of lead-lag compensators which satisfy frequency domain specifications on phase margin, gain margin and phase (or gain) crossover frequency. An analytical and graphical procedure for the compensator design on the Nyquist and Nichols planes is presented with some numerical examples
Analytical Design of Lead-Lag Compensators on Nyquist and Nichols Planes
Full text linkIn this paper the dynamic structure and the control properties of a new form of lead-lag compensator with complex zeros and poles are presented. A simple and exact analytical and graphical method on the Nyquist and Nichols planes for the design of lead-lag compensators satisfying design specifications on gain margin, phase margin and crossover frequency is proposed. Simulations results show the good performances of the presented method
A Straightforward Approach to the Cheap LQ Problem for Continuous-Time Systems in Geometric Terms
Full text linkThis paper addresses the cheap version of the classical linear quadratic (LQ) optimal control problem for continuous-time systems. The approach herein considered differs from those presented in literature, since it consists of applying the tools of the geometric control theory to the Hamiltonian system. In this way, it is possible to compute the stabilizing state-feedback gain achieving optimality by using standard geometric algorithms, whenever the initial state satisfies a suitable necessary and sufficient condition for solvability, also stated in geometric terms
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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