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1.
The H 2-optimal control of continuous-time linear time-invariant systems by sampled-data controllers is discussed. Two different solutions, state space and operator theoretic, are given. In both cases, the H 2 sampled-data problem is shown to be equivalent to a certain discrete-time H 2 problem. Other topics discussed include input-output stability of sampled-data systems, performance recovery in digital implementation of analog controllers, and sampled-data control of systems with the possibility of multiple-time delays 相似文献
2.
Woonchul Ham 《Automatic Control, IEEE Transactions on》1993,38(4):654-658
Adaptive and nonadaptive control algorithms, which make use of a fundamental mathematical property concerning positive definite matrices and Lyapunov stability theory, are proposed for the control of robot manipulators. Using the fact that the matrix dD (q )/dt -2C (q , dq / dt ) is skew symmetric, nonadaptive controllers which have a simplified structure with less computational burden are proposed. Using the dynamic equations for robot manipulators, parameter adaptation rules are developed for updating the controller's partially or totally unknown parameters, generalizing them to model reference adaptive controllers. To further take advantage of the simplified structure of the proposed adaptive controllers, a method for deriving the dynamic model of a robot manipulator which is linear in terms of its parameters is given. This dynamic model is also suitable for the pure identification of the parameters of links and payload of the manipulator 相似文献
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It is shown how to translate an instance of a multirate sampled-data LQG problem into an equivalent, modified, single-rate, shift-invariant problem via a lifting isomorphism approach. Using this approach, one can solve the multirate LQG problem without using periodic system theory or solving periodic Riccati equations and without suffering any increases in state dimension. This translation procedure shows the correct way to translate RMS noise specification to the lifted domain for a multirate Q -design computer-aided-design package 相似文献
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Simultaneous controller design for linear time-invariant systems 总被引:1,自引:0,他引:1
The use of generalized sampled-data hold functions (GSHF) in the problem of simultaneous controller design for linear time-invariant plants is discussed. This problem can be stated as follows: given plants P 1, P 2, . . ., P N , find a controller C which achieves not only simultaneous stability, but also simultaneous optimal performance in the N given systems. By this, it is meant that C must optimize an overall cost function reflecting the closed-loop performance of each plant when it is regulated by C . The problem is solved in three aspects: simultaneous stabilization, simultaneous optimal quadratic performance, and simultaneous pole assignment in combination with simultaneous intersampling performance 相似文献
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It is shown that there is a continuously parameterized family F of n -dimensional single-input single-output (SISO) stabilizable detectable linear system Σ(p ) which contains at least one realization of each reduced, strictly proper transfer function of McMillan degree not exceeding n . The parameterization map p →Σ(p ) is a polynomial function in 2n indeterminates from an open convex polyhedron in R 2n to the linear space of all SISO n -dimensional linear systems 相似文献
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The L 1 optimal control problem with rational controllers for continuous-time systems is considered in which it is shown that the optimal L 1 performance index with rational controllers is equal to that of irrational controllers. A sequence of rational controllers that approximates the optimal index is constructed. Convergence properties of such a sequence are studied. That the corresponding sequence of objective transfer functions is shown to converge in weak-* topology in BV (R +) in the time domain and uniformly in a wider sense in the frequency domain 相似文献
8.
Suppose that for a linear, time-invariant, single-input single-output (SISO) plant a digital dynamic controller has been designed so that the corresponding discrete-time linear feedback control system will satisfy certain specified steady-state error criteria (e.g., the output v ˜(kT ) will follow the input r (kT ) within a certain given error bound). Corresponding to this idealized linear system, the digital implementation of the dynamic controller will result in a nonlinear feedback control system. To what extent the resulting nonlinear digital feedback control system satisfies the steady-state-error criteria of the original idealized linear prototype feedback control system is investigated. Digital controller implementations which use fixed-point arithmetic or floating-point arithmetic are considered. Designs which are well scaled are assumed, i.e., overflow nonlinearities in digital controllers are not addressed 相似文献
9.
For discrete systems, the set of all state covariances X which can be assigned to the closed-loop system via a dynamic controller is characterized explicitly. For any assignable state covariance X , the set of all controllers that assign this X to the closed-loop system is parameterized with an arbitrary orthonormal matrix U of proper dimension 相似文献
10.
It is shown that given any degree of accuracy, there exists a standard discrete-time l 1 problem that can be determined a priori whose solution yields a controller that is almost optimal in terms of the hybrid L ∞-induced norm. This is accomplished by first converting the hybrid system into an equivalent infinite-dimensional discrete-time system using the lifting technique in continuous time, and then approximating the infinite-dimensional parts of the system which model the intersample dynamics. A thorough analysis of the approximation procedure is presented, and it is shown that it is convergent at the rate of 1/n . Explicit bounds that are independent of the controller are obtained to characterize the approximation. It is also shown that the geometry of the induced norm for the sampled-data problem is different from that of the standard l 1 norm, and hence there might not exist a linear isometry that maps the sampled-data problem exactly to a standard discrete-time problem 相似文献
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The problem to be solved involves a highway automation project. The overall system consists of N vehicles (the platoon). Each vehicle is driven by the same input u and the state of the k th vehicle affects the dynamics of the (k +1)th vehicle. Furthermore, the dynamics of each vehicle is affected by its (local) state-feedback controller. Under very general conditions, it is shown that for sufficiently slowly varying inputs, decentralized controllers can be designed so that the platoon maintains its cohesion 相似文献
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The problem of optimal rejection of bounded persistent disturbances is solved in the case of linear discrete-time periodic systems. The solution consists of solving an equivalent time-invariant standard l 1 optimization problem subject to an additional constraint. This constraint assures the causality of the resulting periodic controller. By the duality theory, the problem is shown to be equivalent to a linear programming problem, which is no harder than the standard l 1 problem. Also, it is shown that the method of solution presented applies exactly to the problem of disturbance rejection in the case of multirate sampled data systems. Finally, the results are applied to the problem of robust stabilization of periodic and multirate systems 相似文献
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Robust stability and performance via fixed-order dynamiccompensation: the discrete-time case 总被引:1,自引:0,他引:1
A discrete-time feedback-control-design problem involving parametric uncertainty is considered. A quadratic bound suggested by recent work on discrete-time state-space H ∞ theory is utilized in conjunction with the guaranteed cost approach to guarantee robust stability with a robust performance bound. The principal result involves sufficient conditions for characterizing robust full- and reduced-order controllers with a worst case H 1 performance bound 相似文献
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A general state-space representation is used to allow a complete formulation of the H ∞ optimization problem without any invertibility condition on the system matrix, unlike existing solutions. A straightforward approach is used to solve the one-block H ∞ optimization problem. The parameterization of all solutions to the discrete-time H ∞ suboptimal one-block problem is first given in transfer function form in terms of a set of functions in H ∞ that satisfy a norm bound. The parameterization of all solutions is also given as a linear fractional representation 相似文献
15.
The problem of finding an internally stabilizing controller that minimizes a mixed H 2/H ∞ performance measure subject to an inequality constraint on the H ∞ norm of another closed-loop transfer function is considered. This problem can be interpreted and motivated as a problem of optimal nominal performance subject to a robust stability constraint. Both the state-feedback and output-feedback problems are considered. It is shown that in the state-feedback case one can come arbitrarily close to the optimal (even over full information controllers) mixed H 2/H ∞ performance measure using constant gain state feedback. Moreover, the state-feedback problem can be converted into a convex optimization problem over a bounded subset of (n ×n and n ×q , where n and q are, respectively, the state and input dimensions) real matrices. Using the central H ∞ estimator, it is shown that the output feedback problem can be reduced to a state-feedback problem. In this case, the dimension of the resulting controller does not exceed the dimension of the generalized plant 相似文献
16.
A model for multirate sampled-data systems is presented. A detailed analysis of nonconventional sampled-data control systems (SDCS) is performed. The block multirate input-output model illustrates the control possibilities of multirate SDCS. It is obtained from either a transfer function matrix or a state variable representation. The model provides a direct way to represent, design, and understand either periodic or predictive controllers. A controller design methodology suitable for multivariable, multirate, nonsynchronous SDCS is also presented. The main feature is the freedom to achieve important objectives such as structure assignment, decoupling, and desired transient behavior, as well as reference matching, optimal control, or disturbance rejection 相似文献
17.
Pole assignment in a singular system Edx /dt =Ax +Bu is discussed. It is shown that the problem of assigning the roots of det(sE -(A +BF )) by applying a proportional feedback u =Fx +r in a given singular system is equivalent to the problem of pole assignment of an appropriate regular system. An immediate application of this result is that procedures and computational algorithms that were originally developed for assigning eigenvalues in regular systems become useful tools for pole assignment in singular systems. The approach provides a useful tool for the combined problem of eliminating impulsive behavior and stabilizing a singular system 相似文献
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It is shown that for a given p (1<p ⩽n ), the n -cube network can tolerate up to p 2(n-p)-1 processor failures and remains connected provided that at most p neighbors of any nonfaulty processor are allowed to fail. This generalizes the result for p =n-1, obtained by A.-M Esfahanian (1989). It is also shown that the n -cube network with n ⩾5 remains connected provided that at most two neighbors of any processor are allowed to fail 相似文献
19.
The authors apply H ∞-designed controllers to a generic VSTOL (vertical and short takeoff and landing) aircraft model GVAM. The design study motivates the use of H ∞ techniques, and addresses some of the implementation issues which arise for multivariable and H ∞-designed controllers. An approach for gain scheduling H ∞ controllers on the basis of the normalized comprime factor robust stabilization problem formulation used for the H ∞ design is developed. It utilizes the observer structure unique to this particular robustness optimization. A weighting selection procedure, has been developed for the associated loop-shaping technique used to specify performance. Multivariable controllers pose additional problems in the event of actuator saturations, and a desaturation scheme which accounts for this is applied to the GVAM. A comprehensive control law was developed and evaluated using the Royal Aerospace Establishment piloted simulation facility 相似文献
20.
The focus of this work is L 1-optimal control of sampled-data systems. A converging approximation procedure is derived to compute the L ∞-induced norm of closed-loop finite-dimensional linear time-invariant (LTI) sampled-data systems. An approximation method is developed to synthesize L 1-optimal sampled-data regulators. Finally, an example is provided that illustrates the L 1 analysis and design techniques presented 相似文献