By Topic

Automatic Control, IEEE Transactions on

Issue 12 • Date Dec. 1989

Filter Results

Displaying Results 1 - 24 of 24
  • Comments, with reply, on "Estimating the robust dead time for closed-loop stability" by A.K. El-Sakkary

    Publication Year: 1989
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (88 KB)  

    The commenters illustrate how easy it is to find the upper bound on the robust dead time for closed-loop stability as compared to a method for obtaining only its estimate, proposed in the above-mentioned paper (ibid., vol.33, no.6, p.599-601, June 1988). The author restates his main result and shows that it serves a purpose that was overlooked by the commenters.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comments, with reply, on "Stability of a polytope of matrices: counterexamples" by B.R. Barmish et al

    Publication Year: 1989 , Page(s): 1324 - 1326
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (257 KB)  

    The commenters show that the counterexample given in the above-mentioned paper (ibid., vol.33, no.6, p.569-72, June 1988) does not invalidate the conjecture about the necessary and sufficient conditions for the stability of interval matrices. Comments on the relationship between interval matrices and polytopes of polynomials are also given. The authors reply that their counterexample is valid and attribute the misunderstanding to insufficiently precise wording in their paper.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Control of slowly-varying linear systems

    Publication Year: 1989 , Page(s): 1283 - 1285
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    State feedback control of slowly varying linear continuous-time and discrete-time systems with bounded coefficient matrices is studied in terms of the frozen-time approach. This study centers on pointwise stabilizable systems. These are systems for which there exists a state feedback gain matrix placing the frozen-time closed-loop eigenvalues to the left of a line Re s=-γ<0 in the complex plane (or within a disk of radius ρ<1 in the discrete-time case). It is shown that if the entries of a pointwise stabilizing feedback gain matrix ar continuously differentiable functions of the entries of the system coefficient matrices, then the closed-loop system is uniformly asymptotically stable if the rate of time variation of the system coefficient matrices is sufficiently small. It is also shown that for pointwise stabilizable systems with a sufficiently slow rate of time variation in the system coefficients, a stabilizing feedback gain matrix can be computed from the positive definite solution of a frozen-time algebraic Riccati equation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A two-sided interpolation approach to H optimization problems

    Publication Year: 1989 , Page(s): 1285 - 1290
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    A solution to the two-sided interpolation problem which arises in H optimization theory is obtained. This solution is found in closed form, explicitly in terms of the required interpolation directions. It is simple to obtain and it does not require the application of the relatively complicated matrix Pick-Nevanlinna theory. The solution obtained is of minimum order; due to its simplicity, the order reduction, which occurs at the minimum value of the H-norm, is clearly explained View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On multiple criteria stationary linear quadratic control

    Publication Year: 1989 , Page(s): 1311 - 1313
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    Multiple control criteria and design specifications are, in general, present in control systems design. In this study, all Pareto optimal solutions are characterized for a large class of multiple criteria stationary linear quadratic control problems in terms of associated scalar criterion linear quadratic control problem solutions based on a supporting hyperplane argument, and thus the results are fully constructive. This argument, which was used to establish these results, is believed to be new View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Stability regions of nonlinear dynamical systems: a constructive methodology

    Publication Year: 1989 , Page(s): 1229 - 1241
    Cited by:  Papers (49)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1184 KB)  

    A constructive methodology for estimating stability regions of general nonlinear dynamical systems is developed. The constructive methodology starts with a given Lyapunov function (either a global or a local Lyapunov function) and yields a sequence of Lyapunov functions which are then used to estimate the stability region. The resulting sequence of estimated stability regions is shown to be a strictly monotonic increasing sequence, and yet each of them remains inside the entire stability region. The significance of this methodology includes: its ability to reduce significantly the conservativeness in estimating the stability regions; its computational efficiency; its adaptability; and its sound theoretical basis View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On stabilizing properties of solutions of the Riccati difference equation

    Publication Year: 1989 , Page(s): 1313 - 1316
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    Monotonicity and stabilizing properties of solutions of the Riccati difference equation (RDE) are discussed. The author considers the problem of selecting an initial condition for the RDE in such a way that the update of the Kalman filter gain can be stopped at any time and the resulting frozen filter is asymptotically stable. The author also considers the case in which the initial condition of the RDE may be less than the asymptotic solution. The results are relevant to control and observer design, including the stability of finite-time horizon discrete-time predictive control View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Robust adaptive regulation without persistent excitation

    Publication Year: 1989 , Page(s): 1260 - 1267
    Cited by:  Papers (36)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    A globally convergent adaptive regulator for minimum or nonminimum phase systems subject to bounded disturbances is presented. The control strategy is designed for a particular input-output representation obtained from the state-space representation of the system. The leading coefficient of the novel representation is the product of the observability and controllability matrices of the system. The controller scheme uses a least-squares identification algorithm with a dead zone. The dead zone is chosen to obtain convergence properties on the estimates and on the covariance matrix as well. This allows the definition of modified estimates which secure well-conditioned matrices in the adaptive control law. Explicit bounds on the plant output are given View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An optimal control approach to the decentralized robust servomechanism problem

    Publication Year: 1989 , Page(s): 1268 - 1271
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    A linear-quadratic optimal control approach is presented for designing linear time-invariant decentralized controllers to solve the robust servomechanism problem. It is assumed that not only the plant and the measurements but also the controllers may be subject to certain disturbances. A physically meaningful quadratic cost functional is defined, making it possible to assign desired weights to the errors, to their derivatives, to the system effort, and to the controller efforts. It is shown that the resulting controlled system has many properties like asymptotic tracking, stability, and robustness. The solution does not require much control effort at high frequencies, and the system is guaranteed not to have high frequency oscillations View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A recursive algorithm for coprime fractions and Diophantine equations

    Publication Year: 1989 , Page(s): 1276 - 1279
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    The computation of coprime fractions for proper rational matrices and the solving of the minimal design problem are important in the design of multivariable systems by using polynomial fractional terms. A recursive algorithm, which fully exploits the shift-invariant property of the generalized resultants, is developed to carry out these computations. A method for solving the Diophantine equation that is based on this algorithm is outlined. This results in a significant reduction in computation as compared to the standard methods involving solution of linear algebraic equations. Some comparisons to existing methods show that the present algorithm is computationally more attractive with regard to efficiency and accuracy View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimal disturbance rejection for nonlinear control systems

    Publication Year: 1989 , Page(s): 1242 - 1248
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (644 KB)  

    The problem of optimal disturbance rejection for a general class of multiinput/multioutput (MIMO) nonlinear systems, achieved over a set of stabilizing compensator operators, is formulated in a Banach space setting. Conditions on the operators are imposed on the basis of the inputs as well as the outputs. An existence theorem for optimal solutions is established under some realistic and verifiable conditions. For solving the optimization problem, a generalized recursive nonlinear programming algorithm is passed, and a simple example of nonlinear optimal feedback design is given to show that the problem can be reduced to standard min-max optimization and is hence solvable View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An efficient numerical algorithm for the solution of a class of optimal control problems

    Publication Year: 1989 , Page(s): 1308 - 1311
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    A numerical algorithm for the solution of a class of optimal control problems is presented. This class is characterized as being linear-quadratic in the control, but not necessarily in the state. The algorithm is efficient in that it possesses a high rate of convergence (like Newton's method), but without being sensitive to initialization. In this respect, it combines the advantages of both the first- and second-order algorithms within the framework of a single algorithm. In addition, the algorithm requires less computation and storage than Newton's method View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimal finite wordlength linear quadratic regulation

    Publication Year: 1989 , Page(s): 1218 - 1228
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (996 KB)  

    The authors consider the design of an LQG regulator, implemented in fixed-point arithmetic, which is optimized with respect to its state wordlength and structure. The approach extends previous design methods so that arithmetic errors are directly included. The optimal finite controller gains are computed as a function of the arithmetic wordlength subject to an l2-scaling constant on the controller states. The design method used permits the cost for the (near) optimal structure to be developed so that this can then be used as a basis for comparison to other less complex structures View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An explicit expression for the minimum-phase image of transfer function matrices

    Publication Year: 1989 , Page(s): 1290 - 1293
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    A simple expression is obtained for the transfer function matrix of the minimum-phase image of a left invertible continuous-time invariant system with zeros in the right half-plane that may be of multiplicities greater than one. This expression is obtained by multiplying the system transfer function matrix, from the right, by a special inner matrix, and it is explicitly given in terms of the input zero directions that correspond to the zeros of the system in the right half-plane. The result provides a simple expression for the inner-outer factorization of transfer function matrices, and it can thus be used in H-optimal control View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fast computation of the multivariable stability margin for real interrelated uncertain parameters

    Publication Year: 1989 , Page(s): 1272 - 1276
    Cited by:  Papers (44)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    An alternative implementation of an algorithm for the computation of the multivariable stability margin to check the robust stability of feedback systems with real parametric uncertainty is proposed. This method eliminates the need for the frequency search by reducing it to the testing of a finite number of conditions. These conditions have a special structure that allows a significant improvement in the speed of computation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Asymptotically efficient adaptive allocation schemes for controlled Markov chains: finite parameter space

    Publication Year: 1989 , Page(s): 1249 - 1259
    Cited by:  Papers (13)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (792 KB)  

    The authors consider a controlled Markov chain whose transition probabilities and initial distribution are parametrized by an unknown parameter θ belonging to some known parameter space Θ. There is a one-step reward associated with each pair of control and the following state of the process. The objective is to maximize the expected value of the sum of one-step rewards over an infinite horizon. The loss associated with a control scheme at a parameter value is the function of time giving the difference between the maximum reward that could have been achieved if the parameter were known and the reward achieved by the scheme. Since it is impossible to minimize the loss uniformly for all parameter values, the authors define uniformly good adaptive control schemes and restrict attention to these schemes. They develop a lower bound on the loss associated with any uniformly good control scheme. They construct an adaptive control scheme whose loss equals the lower bound for every parameter value and is therefore asymptotically efficient View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A note on the maximal solution of the periodic Riccati equation

    Publication Year: 1989 , Page(s): 1316 - 1319
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (380 KB)  

    The periodic symmetric solutions of the periodic Riccati differential equation associated with the filtering problem are considered by the authors. It is proven that, under the sole assumption of detectability, there exists a maximal solution. Moreover, such a solution turns out to be strong, i.e. the characteristic multipliers of the associated closed-loop system belong to the closed unit disk. The proof relies on an iterative linearization technique, which calls for a sequence of periodic Lyapunov equations. Similar results are given for the minimal solution View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Decentralized output feedback stabilization of a class of nonlinear interconnected systems

    Publication Year: 1989 , Page(s): 1297 - 1300
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    The problem of decentralized output feedback stabilization of a class of nonlinear interconnected systems is considered. On the basis of the linear-quadratic design, a sufficient condition for the existence of the decentralized output feedback control of the problem is presented. An estimation of the associated stability domain is also given. An application to the decentralized control of a large-scale telescope is presented to illustrate the use of the results View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Minimal sensitivity perfect model matching control

    Publication Year: 1989 , Page(s): 1279 - 1283
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB)  

    A simple and direct procedure for the design of a minimal sensitivity perfect model matching control system is proposed. The key observation is that, in addition to permitting of perfect model matching control, the design parameters leave a great deal of flexibility that can be utilized to reduce the effect of external disturbances. An example is included for illustration View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Relating the gap and graph metrics via the triangle inequality

    Publication Year: 1989 , Page(s): 1296 - 1297
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    A bound relating a special class of constrained optimization problems to their unconstrained counterparts is presented. An application of the results is a bound on the graph metric in terms of the (computable) gap metric View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design of an exact nonlinear controller for induction motors

    Publication Year: 1989 , Page(s): 1304 - 1307
    Cited by:  Papers (91)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    A novel approach to the control of induction motors is presented. The approach is based on differential-geometric concepts for the control of nonlinear systems. Structural properties of the model are pointed out, and a proper selection of physically meaningful system outputs is indicated which yields, by means of static state-feedback, exact state linearization and input-output decoupling of the closed-loop system. The approach is used to design a controller for motor torque and flux. Simulation results are included View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Estimates of asymptotic trajectory bounds in digital implementations of linear feedback control systems

    Publication Year: 1989 , Page(s): 1319 - 1324
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    Estimates are established for trajectory bounds which are easy to calculate, applicable to general controller topologies, and dependent on parameters (i.e. eigenvalues and eigenvectors) of the idealized linear system (i.e. the control system model neglecting quantizers). The approach utilizes the comparison principle in the Lyapunov theory and the properties of minimal matrix norms. The applicability of the results are demonstrated by means of a specific example View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On-line frequency domain information for control of a flexible-link robot with varying payload

    Publication Year: 1989 , Page(s): 1300 - 1304
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    Experimental results are given for the endpoint position control of a single-link, very flexible robot arm carrying an unknown, varying payload. The control objective is to maintain endpoint position accuracy in the presence of flexure effects after rapid movement due to a rigid body slew-angle commanded position. Fast, simple, and efficient frequency domain schemes are used for online controller gain adjustment within an effective scheduling framework. Only endpoint acceleration and motor shaft angle measurements are utilized in relatively simple control laws where the appropriate gains have been scheduled as correlated to modal frequency information corresponding to a varying, unknown payload View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The structure of inner matrices that satisfy multiple directional interpolation requirements

    Publication Year: 1989 , Page(s): 1293 - 1296
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    The structure of an inner matrix that satisfies directional interpolation requirements for nondistinct values at the right half-plane is derived explicitly, in closed form, in terms of the interpolation directions. The simple expression that is obtained for the required inner transfer function matrix has the same structure as the one that has already been found for distinct interpolation requirements. As a result, this expression provides a comprehensive treatment, in the frequency domain, of interpolation problems that arise in many areas of linear system optimization View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

In the IEEE Transactions on Automatic Control, the IEEE Control Systems Society publishes high-quality papers on the theory, design, and applications of control engineering.  Two types of contributions are regularly considered

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
P. J. Antsaklis
Dept. Electrical Engineering
University of Notre Dame