The Experts below are selected from a list of 48 Experts worldwide ranked by ideXlab platform
G.m. Van Der Molen - One of the best experts on this subject based on the ideXlab platform.
-
Submarine H/sup /spl infin// depth control under wave disturbances
IEEE Transactions on Control Systems Technology, 1995Co-Authors: E. Liceaga-castro, G.m. Van Der MolenAbstract:The depth control of submarines in the absence of wave disturbances (deep submergence) is a straightforward task, but at periscope depth the submarine-wave dynamics become very complex. To solve the submarine depth-keeping problem, a procedure for designing H/sup /spl infin// controllers is proposed. This has been obtained by combining polynomial and state-space H/sup /spl infin// methods. The polynomial approach allows the wave disturbances to be included in the design setting as design "parameters". Reformulating the polynomial description in a state-space configuration enables the controller to be calculated using standard design software, e.g., the /spl mu/-toolbox of Matlab. The wave disturbances model, which may be considered to be formed of first-order (oscillating) and drift (second-order) components, is crucial in the proposed design procedure, as it becomes a design "parameter". A successful representation of these disturbances is also included. The numerical problem caused by the ill conditioning of the standard interconnection system was solved by expressing the system in a "block Observable" Realization. The order of the controller was reduced by factorizing the common poles and zeros of the augmented plant. The criterion for selecting the cost-weighting functions is defined in terms of the dynamical system structure of the submarine. The success of the design procedure has been evaluated through a series of nonlinear simulations.
-
Submarine H/sup /spl infin// depth control wave disturbances
Proceedings of 1994 American Control Conference - ACC '94, 1994Co-Authors: E. Liceaga-castro, G.m. Van Der Molen, M. GrimbleAbstract:A procedure for designing H/sup /spl infin// depth submarine controllers is proposed. The design has been obtained by combining polynomial and state space H/sup /spl infin// methods. The polynomial approach allows the low and high wave frequency disturbances to be included in the design setting as design 'parameters'. Reformulating the polynomial control design structure in the state space scheme enables the use of standard design software. The numerical problem caused by the ill conditioning of the standard interconnection system, was solved by expressing the system in a 'block Observable' Realization. The criterion for selecting the cost weighting functions is defined in terms of the dynamical system structure of the submarine. The success of the design procedure has been evaluated through nonlinear simulations.
E. Liceaga-castro - One of the best experts on this subject based on the ideXlab platform.
-
Submarine H/sup /spl infin// depth control under wave disturbances
IEEE Transactions on Control Systems Technology, 1995Co-Authors: E. Liceaga-castro, G.m. Van Der MolenAbstract:The depth control of submarines in the absence of wave disturbances (deep submergence) is a straightforward task, but at periscope depth the submarine-wave dynamics become very complex. To solve the submarine depth-keeping problem, a procedure for designing H/sup /spl infin// controllers is proposed. This has been obtained by combining polynomial and state-space H/sup /spl infin// methods. The polynomial approach allows the wave disturbances to be included in the design setting as design "parameters". Reformulating the polynomial description in a state-space configuration enables the controller to be calculated using standard design software, e.g., the /spl mu/-toolbox of Matlab. The wave disturbances model, which may be considered to be formed of first-order (oscillating) and drift (second-order) components, is crucial in the proposed design procedure, as it becomes a design "parameter". A successful representation of these disturbances is also included. The numerical problem caused by the ill conditioning of the standard interconnection system was solved by expressing the system in a "block Observable" Realization. The order of the controller was reduced by factorizing the common poles and zeros of the augmented plant. The criterion for selecting the cost-weighting functions is defined in terms of the dynamical system structure of the submarine. The success of the design procedure has been evaluated through a series of nonlinear simulations.
-
Submarine H/sup /spl infin// depth control wave disturbances
Proceedings of 1994 American Control Conference - ACC '94, 1994Co-Authors: E. Liceaga-castro, G.m. Van Der Molen, M. GrimbleAbstract:A procedure for designing H/sup /spl infin// depth submarine controllers is proposed. The design has been obtained by combining polynomial and state space H/sup /spl infin// methods. The polynomial approach allows the low and high wave frequency disturbances to be included in the design setting as design 'parameters'. Reformulating the polynomial control design structure in the state space scheme enables the use of standard design software. The numerical problem caused by the ill conditioning of the standard interconnection system, was solved by expressing the system in a 'block Observable' Realization. The criterion for selecting the cost weighting functions is defined in terms of the dynamical system structure of the submarine. The success of the design procedure has been evaluated through nonlinear simulations.
Ulle Kotta - One of the best experts on this subject based on the ideXlab platform.
-
Two Approaches for State Space Realization of NARMA Models: Bridging the Gap
Mathematical and Computer Modelling of Dynamical Systems, 2002Co-Authors: Ulle Kotta, Nader SadeghAbstract:This paper studies the necessary and sufficient conditions for Observable Realization of a general class of nonlinear high-order input-output difference equations. In particular, it proves the equivalence of the two seemingly different existing approaches in the literature. The paper also provides a subclass of NARMA input-output models that are guaranteed to have an Observable Realization. It is shown that this class covers several important subclasses of existing NARMA models.
-
Transfer equivalence and Realization of nonlinear higher order i/o difference equations using maple
IFAC Proceedings Volumes, 1999Co-Authors: Ulle Kotta, Alan S. I. ZinoberAbstract:Abstract The paper presents a contribution to the development of symbolic, computation tools for discrete-time nonlinear control systems. It presents certain modelling problems to show what can be achieved in nonlinear control with symbolic computation. A set of procedures is developed in Maple V that test if a given input-output (i/o) difference equation is realizable in the classical state space form, and for simple control systems also find the transformation. Other procedures test whether two (or more) input-output difference equations are equivalent, and find the minimal (irreducible) representation of the i/o model. The irreducible form is the basis for constructing the minimal, i.e. accessible and Observable, Realization. The application of the developed procedures is demonstrated on the example of the model of the grain-drying process, obtained via identification.
-
TRANSFER EQUIVALENCE AND Realization OF NONLINEAR HIGHER ORDER INPUT/OUTPUT DIFFERENCE EQUATIONS USING MATHEMATICA
Journal of Circuits Systems and Computers, 1999Co-Authors: Ulle Kotta, Maris TõnsoAbstract:This paper presents a contribution to the development of symbolic computation tools for discrete-time nonlinear control systems. A set of functions is developed in Mathematica 3.0 that test if the higher order input/output difference equation is realizable in the classical state-space form, and for simple examples, also find such state equations. The approach relies on a new notion of equivalence of higher order difference equations which yields a minimal (i.e. accessible and Observable) Realization and generalizes the notion of transfer equivalence to the nonlinear case. The application of the developed functions is demonstrated on three examples obtained via identification.
Alan S. I. Zinober - One of the best experts on this subject based on the ideXlab platform.
-
Brief Transfer equivalence and Realization of nonlinear higher order input-output difference equations
Automatica, 2001Co-Authors: í. Kotta, Alan S. I. ZinoberAbstract:Two fundamental modelling problems in nonlinear discrete-time control systems are studied using the language of differential forms. The discrete-time nonlinear single-input single-output systems to be studied are described by input-output (i/o) difference equations, i.e. a high order difference equation relating the input, the output and a finite number of their time shifts. A new definition of equivalence is introduced which generalizes the notion of transfer equivalence well known for the linear case. Our definition is based upon the notion of an irreducible differential form of the system and was inspired by the analogous definition for continuous-time systems. The second problem to be addressed is the Realization problem. The i/o difference equation is assumed to be in the irreducible form so that one can obtain an accessible and Observable Realization. Necessary and sufficient conditions are given for the existence of a (local) state-space Realization of the irreducible i/o difference equation. These conditions are formulated in terms of the integrability of certain subspaces of one-forms, classified according to their relative degree. The sufficiency part of the proof gives a constructive procedure (up to finding the integrating factors and integration of the set of one-forms) for obtaining a locally Observable and accessible state-space system. If the system is not in the irreducible form, one has first to apply the reduction procedure to transform the system into the irreducible form.
-
Transfer equivalence and Realization of nonlinear higher order i/o difference equations using maple
IFAC Proceedings Volumes, 1999Co-Authors: Ulle Kotta, Alan S. I. ZinoberAbstract:Abstract The paper presents a contribution to the development of symbolic, computation tools for discrete-time nonlinear control systems. It presents certain modelling problems to show what can be achieved in nonlinear control with symbolic computation. A set of procedures is developed in Maple V that test if a given input-output (i/o) difference equation is realizable in the classical state space form, and for simple control systems also find the transformation. Other procedures test whether two (or more) input-output difference equations are equivalent, and find the minimal (irreducible) representation of the i/o model. The irreducible form is the basis for constructing the minimal, i.e. accessible and Observable, Realization. The application of the developed procedures is demonstrated on the example of the model of the grain-drying process, obtained via identification.
A. Cela - One of the best experts on this subject based on the ideXlab platform.
-
On the existence of minimal and canonical Realizations of linear periodic discrete time systems
Proceedings of 35th IEEE Conference on Decision and Control, 1996Co-Authors: El Y. Mrabet, H. Bourles, A. CelaAbstract:This note deals with the problem of the existence of a canonical (i.e. completely reachable and Observable) Realization (CR) for a linear periodic discrete-time (LPDT) system given by its periodic polynomial matrix description (PPMD). Contrary to linear time-invariant (LTI) systems, it is shown here that a CR exists only for a class of LPDT systems and that consequently minimal and canonical ones are not equivalent: namely minimal (i.e. with the least possible dimension) Realization (MR) of a LPDT system is linked with controllability and reconstructability, CR is linked with reachability and observability. Minimal order, necessary and sufficient conditions to ensure the existence of a MR and a CR of LPDT systems are characterized.
