A comparison of the standard concepts in MRAC design suggests that a combination of the implicit and the explicit design techniques may lead to an improvement of the overall system performance in the presence of unmod...
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ISBN:
(纸本)0080417175
A comparison of the standard concepts in MRAC design suggests that a combination of the implicit and the explicit design techniques may lead to an improvement of the overall system performance in the presence of unmodelled dynamics. Using the ideas of adaptive stability augmentation a combined stability augmented modelreference design is proposed. By utilizing the closed-loop control error, a simple auxiliary controller is tuned, using a normalized M.I.T. rule for the parameter adjustment. The M.I.T. adjustment is protected against the effects of unmodelled dynamics by lowpass filtering of the gradient. The proposed method is verified through simulation results indicating that the method may lead to an improvement of the model reference controller in the presence of unmodelled dynamics.
In this work, we consider uncertain LTI SISO systems whose uncertainty is expressed in terms of frequency inequality. This latter is related to the concept of robust strictly positive real transfer function introduced...
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In this work, we consider uncertain LTI SISO systems whose uncertainty is expressed in terms of frequency inequality. This latter is related to the concept of robust strictly positive real transfer function introduced in this paper. By suitably combining this concept with that of almost strictly positive realness, it is possible to define an approximate pole assignment objective and design a reduced order adaptive control scheme characterized by a globally asymptotically stable behaviour of the output error, internal stability and boundedness of the controller parameters.
A digital model-reference flight control system is designed for a VTOL aircraft which has stable zeros but may have a number of unstable zeros when discretized. The proposed design uses both the step invariant and mat...
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A digital model-reference flight control system is designed for a VTOL aircraft which has stable zeros but may have a number of unstable zeros when discretized. The proposed design uses both the step invariant and matched-pole-zero models and is based on the matching of the transfer function from the reference input to the plant input. This design eliminates the discretization error better than and has much superior performance to, the previously proposed method which uses only the truncated step invariant model of the plant
Based on modelreference techniques, a new interative learning control scheme is proposed for control of robot manipulators. The proposed learning controller is combined with a nominal H ∞ model-following controller(...
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Based on modelreference techniques, a new interative learning control scheme is proposed for control of robot manipulators. The proposed learning controller is combined with a nominal H ∞ model-following controller(MFC) to ensure stability and convergence of the modelreference tracking error. The learning operator minimizes an H ∞ -norm, and is obtained by solving an algebraic Riccati equation. A computer simulation for a two-joint manipulator is given to show the convergence of the manipulator trajectories when manipulator parameter uncertainties exist.
The idea of this paper is to present, in a more convenient way for undergraduate students of chemical engineering, the IMC control philosophy as an alternative tuning procedure of PID controllers based on the Integral...
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The idea of this paper is to present, in a more convenient way for undergraduate students of chemical engineering, the IMC control philosophy as an alternative tuning procedure of PID controllers based on the Integral Square Error (ISE) criterion. The Internal modelcontrol (IMC) structure is the starting point of this tuning procedure. Classic Proportional-Integral (PI) and Proportional-Integral-Derivative (PID) feedback controllers are then obtained for most chemical dynamic system representations with different approximations of the deadtime. The set of the PID parameters is further related to the ISE-optimum value of the IMC filter parameter r. Since the tuning of an IMC-РID can be obtained from a relatively analytic easy procedure, it is of major interesting for teaching aids for control theory. This paper includes a step-by-step description of the IMC design procedure together with an example that shows how reasonable are the tunings based on this approach when compared with the traditional Ziegler-Ni chois (Z-N) tuning rules.
This paper presents a neural-network-based PID-like control strategy applicable to a class of nonlinear control problems commonly encountered in the process-control industry. An artificial neural network is used to pr...
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This paper presents a neural-network-based PID-like control strategy applicable to a class of nonlinear control problems commonly encountered in the process-control industry. An artificial neural network is used to provide compensation of the plant's nonlinear dynamics so that the overall closed-loop system can be described in terms of an equivalent error system. In the paper, the strategy is carefully described, and then evaluated and compared with an alternative control system design which uses conventional gain-scheduled PID controllers. The paper includes real-time experimental results in applying the proposed technique for level control of a coupled-tanks system.
The design of a robust non-linear feedback controller incorporating integral and derivative actions is presented for non-linear systems with relative order two. The design method is applied to product concentration tr...
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In this note, a new standard model reference control (NSMRC) to arbitrarily fast linear single-input single-output time-varying plants with relative degree one is presented. A modified version of standard model refere...
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In this note, a new standard model reference control (NSMRC) to arbitrarily fast linear single-input single-output time-varying plants with relative degree one is presented. A modified version of standard model reference control (SMRC) structure is developed which incorporates the concept of variable structure design and null adaptation process for fast time-varying plants. It is shown that the output error will converge to zero in finite time without any restriction on the time-varying rate of the plant parameters while all signals inside the closed-loop system remain uniformly bounded so long as some design parameters are chosen properly (large). Superior transient responses as well as convergence properties can be observed from the simulation results provided.
Motivated by recent works on parametrization of multivariable plants for modelreference adaptive control (MRAC), a new robust model reference control (MRC) scheme for a class of multivariable unknown plants is presen...
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Motivated by recent works on parametrization of multivariable plants for modelreference adaptive control (MRAC), a new robust model reference control (MRC) scheme for a class of multivariable unknown plants is presented. The salient feature of this control scheme is the improved performance of the output-tracking property, which is hardly attainable by the traditional MRAC schemes. The controller here is devised using the concept of variable structure design which prevails in the robust control context. It is shown by a Lyapunov approach that without any persistent excitation the global stability of the overall system is achieved and the tracking errors will converge to a residual set. The size of that set can be directly related to the size of unmodelled dynamics and output disturbances explicitly as long as a set of control parameters is chosen properly (large).
A mixed H-2/H-infinity optimal problem is presented for both disturbance attenuation and model mismatching minimization. Its solution is in the form of a two-degrees-of-freedom controller, whose feedback and feedforwa...
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A mixed H-2/H-infinity optimal problem is presented for both disturbance attenuation and model mismatching minimization. Its solution is in the form of a two-degrees-of-freedom controller, whose feedback and feedforward paths can be independently designed. If the conditions for exact model matching are not met, an inexact model matching problem is addressed. This solution provides an effective model matching design methodology for non-minimum phase plants.
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