The paper discusses in detail a new method for indirect model reference adaptive control (MRAC) of linear time-invariant continuous-time plants with unknown parameters. The method involves not only dynamic adjustment ...
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The paper discusses in detail a new method for indirect model reference adaptive control (MRAC) of linear time-invariant continuous-time plants with unknown parameters. The method involves not only dynamic adjustment of plant parameter estimates but also those of the controller parameters. Hence the overall system can be described by a set of non-linear differential equations as in the case of direct control. Many of the difficulties encountered in the conventional indirect approach, where an algebraic equation is solved to determine the control parameters, are consequently bypassed in this method. The proof of stability of the equilibrium state of the overall system is found to be different from that used in direct control. Using Lyapunov's theory, it is first shown that the parameter errors between the parameter estimates of the identifier and the true parameters of the plant, as well as those between the actual parameters of the controller and their desired values, are bounded. Following this, using growth rates of signals in the adaptive loop as well as order arguments, it is shown that the error equations are globally uniformly stable and that the tracking (control) error tends to zero asymptotically. This in turn establishes the fact that both direct and indirect modelreferenceadaptive schemes require the same amount of prior information to achieve stable adaptivecontrol.
A new variable structure model reference adaptive control scheme with integration is proposed to achieve robustness to modelling uncertainties in this paper. A key feature of this scheme is that the knowledge of neith...
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A new variable structure model reference adaptive control scheme with integration is proposed to achieve robustness to modelling uncertainties in this paper. A key feature of this scheme is that the knowledge of neither the parameters of the upper bounding function on the modelling uncertainties nor the upper bound on the norm of the matching controller parameters is required. Other advantages of the scheme are its excellent transient performance and asymptotic zero output tracking error. Simulation results demonstrated that the chattering of the scheme is effectively compensated by incorporation of an integrator.
A unified approach is presented for nonlinear H-2, H-infinity, and mixed H-2/H-infinity attitude control of spacecraft systems, with external disturbances and parameter perturbations considered. The design objective i...
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A unified approach is presented for nonlinear H-2, H-infinity, and mixed H-2/H-infinity attitude control of spacecraft systems, with external disturbances and parameter perturbations considered. The design objective is to specify a controller such that the quadratic optimal control performance H-infinity or mixed H-2/H-infinity performances can be achieved. It is shown that these problems are special cases of the so-railed two-player Nash differential game problem. An explicit solution to the coupled Riccati-like equations of the nonlinear Nash game control problem can be obtained when nonlinear minimax theory and linear-quadratic optimal control techniques are combined. Moreover, because of the skew symmetric property of the spacecraft system and adequate choice of state variable transformation, these problems can be reduced to solving two algebraic Riccati-like equations. Furthermore, a closed-form solution to these two algebraic equations can be obtained with a very simple form for the preceding control designs. Finally, three experimental simulation results based on the ROCSAT-1 spacecraft system are presented to demonstrate the effectiveness of the proposed design methods.
A decentralized model reference adaptive control (MRAC) scheme is proposed and applied to design a multivariable control system of a dual-spool turbofan *** studies show good static and dynamic performance of the syst...
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A decentralized model reference adaptive control (MRAC) scheme is proposed and applied to design a multivariable control system of a dual-spool turbofan *** studies show good static and dynamic performance of the system over the fullflight envelope. Simulation results also show the good effectiveness of reducing interactionin the multivariable system with significant coupling. The control system developed has awide frequency band to satisfy the strict engineering requirement and is practical for engineering applications.
In this paper, a robust model reference adaptive controller based on variable-structure strategy is designed for a class of nonlinear systems with uncertain parameters and bounded external disturbances. Without a prio...
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In this paper, a robust model reference adaptive controller based on variable-structure strategy is designed for a class of nonlinear systems with uncertain parameters and bounded external disturbances. Without a priori knowledge of bounded disturbance,both the unknown system parameters and the upper bound of external disturbance are estimated by the design of adaptive law to ensure the accessibility of sliding mode and the global stability of the closed-loop system. Theoretical analysis and simulation results show the robustness and effectiveness of this controller.
Damage to an adaptive structure poses an additional danger due to the presence of an active control system. The control system needs to be robust or adaptive in order to prevent unpredicted structural damage from caus...
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This paper presents a decentralized robust model reference adaptive control design for continuous time linear time invariant interconnected large-systems in the presence of" disturbances and/or unmodeled dynamics...
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This paper presents a decentralized robust model reference adaptive control design for continuous time linear time invariant interconnected large-systems in the presence of" disturbances and/or unmodeled dynamics. The scheme of adaptation is based on the concept of dynamic certainty equivalence (DyCE) and incorporates the design of a decentralized fixed(non-adaptive) compensator in the error feedback loop. The fixed compensator is used to attain the strictly properness of an error transfer function matrix against the cross-coupling and unmodeled dynamics effects, furthermore it can realize the high performance of a tracking. The key features of our control design are: (1) use of H ∞ minimization design for the decentralized fixed compensator, and (2) use of a robust high-order estimator with a-modification for the effects of cross-coupling.
A new decentralized adaptivecontrol scheme is presented for linear time invariant systems with first order interconnections. The proposed control scheme with “proportional plus integral” terms is used to improve ...
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A new decentralized adaptivecontrol scheme is presented for linear time invariant systems with first order interconnections. The proposed control scheme with “proportional plus integral” terms is used to improve the convergence rate and the ultimate bound of the tracking error. It is important to note that the adaptive scheme uses lower adaptive gains and smaller control inputs to avoid input saturation and oscillatory behavior. Simulation results are illustrated for controlling a dual inverted pendulum and a multivariable turbofan engine using the proposed adaptive scheme. These simulations validate out conclusions.
作者：
Juang, JNPhan, MQNASA
Langley Res Ctr Struct Dynam Branch Hampton VA 23681 USA Princeton Univ
Dept Mech & Aerosp Engn Princeton NJ 08544 USA
A recursive algorithm is presented for the deadbeat predictive control that brings the output response to rest after a few time steps. The main idea is to put together the system identification process and the deadbea...
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A recursive algorithm is presented for the deadbeat predictive control that brings the output response to rest after a few time steps. The main idea is to put together the system identification process and the deadbeat control design into a unified step. It starts with reformulating the conventional multistep output-prediction equation to explicitly include the coefficient matrices to weight past input and output time histories for computation of feedback control force. The formulation thus derived satisfies simultaneously the system identification and the deadbeat control requirements. As soon as the coefficient matrices are identified satisfying the output prediction equation, no further work is required to design a deadbeat controller The method can be implemented recursively just as any typical recursive system identification technique.
An indirect filed-oriented induction motor (IM) position servo drive with adaptive rotor time-constant estimation and an on-line trained neural network controller Is presented. First, the rotor time-constant is estima...
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An indirect filed-oriented induction motor (IM) position servo drive with adaptive rotor time-constant estimation and an on-line trained neural network controller Is presented. First, the rotor time-constant is estimated real-time on the basis of the modelreferenceadaptive system (MRAS) theory. Next, a linear model-following controller (LMFC) is designed according to the estimated plant model to allow the state responses of the plant to follow the referencemodel. Then an augmented signal generated from the proposed neural network controller, whose connective weights are trained on-line according to the model-following error of the states, is added to the LMFC system to preserve a favorable model-following characteristic under various operating conditions.
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