A methodology of discontinuous feedback and continuous feedforward control is developed to achieve accurate decoupled tracking in a class of nonlinear systems in the presence of disturbances and parameter variations. ...
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A methodology of discontinuous feedback and continuous feedforward control is developed to achieve accurate decoupled tracking in a class of nonlinear systems in the presence of disturbances and parameter variations. The method is based on an improved variable structure control with a sliding mode. First, a desired output time response (forced model) is generated in time series with a microprocessor. Then discontinuous feedback and continuous feedforward controls are applied in order to force the output to track its desired time response. By introducing this modified model following control, the error between the output of the plant and model is made very small. Thus this mitigates the extent of undesirable chattering due to switching delays, neglected small time constants, etc. The convergence of the error state to the origin is proved by using “direct method of Liapunov.” With the rapid progress in microelectronics and powerelectronics high-performance actuators, sensors are now available. Therefore the proposed control strategy can be easily implemented resulting in revolutionary high-quality control in processes. The methodology is practically applied to decoupled water-level controls for two tanks connected with pipes, in which water-levels are interacting on one another. All the control strategies are implemented by a high performance microprocessor which is now available at reasonable cost. It is found that this novel controller obtained performs extremely satisfactorily and is superior to the “conventional” controller for the process. In addition, the controller can be simply designed, since it does not require accurate modeling. but it is sufficient to know only the bounds of model parameter values and the magnitudes of the disturbances.
A methodology of discontinuous feedback and continuous feedforward control is developed to achieve accurate decoupled tracking in a class of nonlinear time varying systems in the presence of disturbances, parameter va...
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A methodology of discontinuous feedback and continuous feedforward control is developed to achieve accurate decoupled tracking in a class of nonlinear time varying systems in the presence of disturbances, parameter variations and nonlinear dynamic interactions. The method is based on an improved variable structure control with a sliding mode. The convergence of the error state to the origin is proved by using the "direct method of Liapunov". Then the developed method is practically applied to decoupled tracking control for a two-degrees-of-freedom manipulator. The joint position trajectories are observed to be smooth and to track the desired trajectories accurately.
The role of modelreference adaptive control is under consideration for a computer based feedback system which will regulate the infusion rate of a drug (nitroprusside) in order to maintain desired blood pressure. Bec...
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The role of modelreference adaptive control is under consideration for a computer based feedback system which will regulate the infusion rate of a drug (nitroprusside) in order to maintain desired blood pressure. Because parameters are different for each patient and furthermore are variable with time, an adaptive algorithm is desirable for maintaining both steady state and transient specifications. To this effect, computer simulation has shown that direct (or implicit) modelreference procedures might be successfully applied to the control of blood pressure despite the uncertainty in the delays, time constant and gains. Additional efforts concerned with the actual demonstration of these concepts on dogs have further supported the role of adaptive control for blood pressure regulation.
A deterministic design technique for a class of modelreference invariant control systems for linear multivariable plants with unknown parameters is described. The controller does not depend explicitly upon the plant ...
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A deterministic design technique for a class of modelreference invariant control systems for linear multivariable plants with unknown parameters is described. The controller does not depend explicitly upon the plant uncertainties and the modelling accuracy becomes a less stringent requirement. By introducing the system characteristic variable, the design is carried out on the basis of an equivalent but decoupled lower-order system. The stability of the resulting system is analyzed and a sufficient condition is shown to be that [G(s)] -1 is strictly stable where G(s) is the input output transfer matrix of the plant. The control signal is of the feedback type and is implemented by measuring only the system outputs and their lower order derivative signals
A new method for designing a discrete modelreference adaptive control system is presented. This method avoids the restriction of the minimum phase system by the adaptive controller designed for an autoregressive mode...
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A new method for designing a discrete modelreference adaptive control system is presented. This method avoids the restriction of the minimum phase system by the adaptive controller designed for an autoregressive model with dead time of the plant. First, a stable adaptive control system is designed for an AR model with dead time, based on Lyapunov's direct method. The derived adaptation control algorithm can be implemented using only the available input-output data of the plant. Next, in order to illustrate the effectiveness of this model for many different types of plants, the results of computer simulation are given. Finally, the design parameters of the model are discussed.
A laboratory process serving as a demonstration object in education and research on the field of modern control theory is presented. Modern control theory is used to regulate a double pendulum hinged to a cart on a ra...
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A laboratory process serving as a demonstration object in education and research on the field of modern control theory is presented. Modern control theory is used to regulate a double pendulum hinged to a cart on a rail. In contrast to foregoing reports on this well-known experimental system, solely one angle of the double pendulum is measured. Moreover, the cart-pendulum system is stabilized in all of its four equilibrium points. A model reference control of the cart attenuates the influence if the position-dependent friction on the rail. The cart-pendulum system is controlled by linear observer-based state variable feedback. Experimental results are presented.
A model reference control strategy is discussed for the production of monodisperse polymers and polymers of any pre-defined molecular weight distribution from ‘living’ anionic polymerizations carried out in a small-...
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A model reference control strategy is discussed for the production of monodisperse polymers and polymers of any pre-defined molecular weight distribution from ‘living’ anionic polymerizations carried out in a small-scale tubular reactor system. Initially it was assumed that when a fixed (monomer)/(initiator) ratio was introduced into the reactor that it was possible to produce monodisperse polymer with a predictable average molecular weight and further that by perturbing the (monomer)/(initiator) ratio in a prescribed monomer with time that an integral product of any molecular weight distribution (MWD) could be achieved. Experimental results indicate that the limitations of this simple approach were (i) the (initiator) was severely altered by adventitious side reactions, (ii) axial dispersion in the reactor and a finite reaction initiation rate resulted in an undesirable broadening effect on the MWD. To overcome these limitations a spectrophotometer has been incorporated into an input adaptive loop to control the living chain end concentration in the reactor and the axial dispersion effects on the MWD as deduced from gel permeation chromatography measurements have been used to adjust the input feed rate of the reactants; both modifications are currently being tested and are outlined here. In principle perturbing the feed to a polymerization reactor can be applied to any polymerization process to alter the MWD envelope of the product but the efficacy of this approach is sensitive to the mechanism of the polymerization reaction and the reactor configuration.
This paper shows that the same algorithm can be viewed as a modelreference Adaptive System, or as a Self-Tuning Regulator . Overall unconditional stability is proved in the deterministic case. In addition, a theorem ...
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This paper shows that the same algorithm can be viewed as a modelreference Adaptive System, or as a Self-Tuning Regulator . Overall unconditional stability is proved in the deterministic case. In addition, a theorem of convergence is provided as a general tool to analyse the stability of some prediction error recursive schemes.
Some connections between the modelreference approach and the self-tuning approach to adaptive control are displayed. The discussion is largely based on an analysis of the recursive, stochastic self-tuning algorithm, ...
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Some connections between the modelreference approach and the self-tuning approach to adaptive control are displayed. The discussion is largely based on an analysis of the recursive, stochastic self-tuning algorithm, in which convergence is studied in terms of stability of an associated differential equation. This provides a bridge to the well-known stability considerations which are characteristic of the design of modelreference adaptive system.
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