A modified output error method (MOEM) for model reference adaptive control (MRAC) and identification (MRAI) is introduced. The regressors are properly chosen so that the open-loop system can be compactly expressed as ...
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A modified output error method (MOEM) for model reference adaptive control (MRAC) and identification (MRAI) is introduced. The regressors are properly chosen so that the open-loop system can be compactly expressed as a stable system with an input linear with respect to the unknown plant parameters. The output error satisfies a constructible stable filtered equation. The method does not require any strictly positive real or arbitrary stable filterings, and the uncertainty on the magnitude of the high-frequency gain of the plant does not result in an overparameterization of the identifier. Sufficient conditions on the reference input under which the parameter and output errors converge exponentially to zero are also given.< >
We report on recent progress in the development of a computer-aided engineering (CAE) environment for nonlinear control system analysis and design based on sinusoidal-input describing function (SIDF) methods. Several ...
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We report on recent progress in the development of a computer-aided engineering (CAE) environment for nonlinear control system analysis and design based on sinusoidal-input describing function (SIDF) methods. Several major additions have been made to our nonlinear controls CAE software: ACSL macros were developed to allow the generation of SIDF models of nonlinear plants in a manner analogous to that of the SIMNON-based software developed earlier, and MATLAB routines were developed for the analysis of these models and for the design of general nonlinear controllers based on them. This software provides an integrated tool set for treating very general nonlinear systems with no restrictions on system order, number of nonlinearities, configuration, or nonlinearity type. Based on the new software presented here, the use of SIDF-based nonlinear control system analysis and design methods is substantially easier to carry out and more powerful than before
This paper examines the system identification problem from the standpoint of control system design. Noting first that nearly all robust control design methods require explicit worst-case/deterministic bounds on the ex...
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This paper examines the system identification problem from the standpoint of control system design. Noting first that nearly all robust control design methods require explicit worst-case/deterministic bounds on the existing plant uncertainty, it is argued that the class of system identification methods which are inherently compatible with robust control design methods-or control-oriented is a subset of the class of system identification methods which yield an explicit worst-case/deterministic bound on the resulting identification error. An abstract theoretical framework for control-oriented system identification is then developed. This framework is inherently worst-case/deterministic in nature, and makes precise such notions as identification error, algorithm convergence, and algorithm optimality from a worst-case/deterministic standpoint. Finally, the abstract theoretical framework is utilized to formulate and solve two related control-oriented system identification problems for stable, linear, shift-invariant, distributed parameter plants. In each of these problems the assumed apriori information is minimal, consisting only of a lower bound on the relative stability of the plant, an upper bound on a certain gain associated with the plant, and an upper bound on the noise level. In neither case are any assumptions made concerning the structure of either the plant (i.e., dynamic order, relative order, etc.) or the noise (i.e., zero-mean, etc.). The first of these problems involves identification of a point sample of the plant frequency response from a noisy, finite, output time series obtained in response to an applied sinusoidal input with frequency corresponding to the frequency point of interest.
The authors present a self-organizing artificial neural network (ANN) that exhibits deterministically reliable behavior to noise interference when the noise does not exceed a specified level of tolerance. The complexi...
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The authors present a self-organizing artificial neural network (ANN) that exhibits deterministically reliable behavior to noise interference when the noise does not exceed a specified level of tolerance. The complexity of the proposed ANN, called DIGNET, in terms of neuron requirements versus stored patterns, increases linearly with the number of stored patterns and their dimensionality. The self-organization of DIGNET is based on the idea of competitive generation and elimination of attraction wells in the pattern space. The same neural network can be used for both pattern recognition and classification.< >
This paper analyzes worst case identification of linear shift invariant systems with an l 1 error criterion. A characterization of optimal algorithms and intrinsic errors of identification is given. The application o...
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This paper analyzes worst case identification of linear shift invariant systems with an l 1 error criterion. A characterization of optimal algorithms and intrinsic errors of identification is given. The application of this characterization is made to identification in l 1 . The assumed apriori information on the plant are bounds on the system gain and decay rate of the impulse response of the unknown system and the experimental data is assumed to be a finite set of corrupted impulse or step response samples of the systems. Comparisons are made with the H ∞ system identification problem. Comments on the l 1 identification of small signal models of smooth nonlinear discrete time systems are made.
A method is given to estimate the geometry and motion of a moving body surface from image sequences. To this aim a parametric model of the surface is used, in order to reformulate the problem to one of parameter estim...
A method is given to estimate the geometry and motion of a moving body surface from image sequences. To this aim a parametric model of the surface is used, in order to reformulate the problem to one of parameter estimation. After linearization of the model standard linear estimation methods can be used to estimate the parameters. The main contribution of this paper is that a method is provided to perform the linearization without specifying the model. Therefore structure from motion estimation and nonrigid body motion estimation can be performed regardless of the model.
Task-dependent response - eg, in instrument calibration, spatial positioning and the like - is a long nursed requirement: transition to the end state very fast, albeit imprecise, followed by slower but very accurate f...
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The application of a linear multivariable control law design methodology to an autopilot design for large transport aircraft is described. The design method is an explicit model-matching approach, whereby compensator ...
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The application of a linear multivariable control law design methodology to an autopilot design for large transport aircraft is described. The design method is an explicit model-matching approach, whereby compensator parameters are tuned via a least-squares optimization approach to minimize the error between the desired and the actual closed-loop frequency responses. This method incorporates some recent theoretical advances, including controller parameterization and plant factorization, and has been implemented within the ISICLE software package, a MATLAB-based control design toolbox. A desirable feature of the ISICLE design software is the capability to constrain the compensator dynamic order and structure, issues motivated by the necessity for low complexity implementations in order to simplify gain scheduling and limit protection.< >
In this paper the Linear Constrained Regulation Problem for discrete-time systems is studied. The first part of the paper deals with the problem of existence of linear state-feedback control laws that transfer asympto...
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In this paper the Linear Constrained Regulation Problem for discrete-time systems is studied. The first part of the paper deals with the problem of existence of linear state-feedback control laws that transfer asymptotically to the origin all initial states belonging to a polyhedral subset of state space while linear state and control constraints are respected. Then an eigenstructure assignment technique is developed for derivation of a solution to this problem. The results presented in the paper are based on the properties of systems possessing polyedral positively invariant sets.
In this paper, we report on recent advances in the design of fully nonlinear controllers for amplitude-sensitive nonlinear plants using sinusoidal-input describing function methods. This work includes the development ...
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In this paper, we report on recent advances in the design of fully nonlinear controllers for amplitude-sensitive nonlinear plants using sinusoidal-input describing function methods. This work includes the development of a new nonlinear controller synthesis approach that includes derivative action in an inner-loop feedback path (nonlinear rate feedback), and its application to a motor + load model with torque saturation and stiction. This approach is capable of treaing nonlinear systems of a very general nature, with no restrictions as to system order, number of nonlinearities, configuration, or nonlinearity type; additionally, the techniques can be generalized for the design of nonlinear controllers of different structures. The end result is a closed-loop nonlinear control system that is relatively insensitive to reference-input amplitude.
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