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Automatic Control, IEEE Transactions on

Issue 3 • Date March 1993

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Displaying Results 1 - 25 of 25
  • Comments on "Euclidean null-controllability of linear systems with distributed delays in control" by M. Khambadkone

    Publication Year: 1993
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (101 KB)  

    A counterexample is given to show the invalidity of the main result in the above-titled paper (ibid., vol.AC-27, no.2, pp.210-211, Feb. 1982).<> View full abstract»

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  • Comments on "On the robust control of robot manipulators by M.W. Spong

    Publication Year: 1993 , Page(s): 511 - 512
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (120 KB)  

    In the above-title paper (ibid., vol.37, no.11, pp.1782-1786, Nov. 1992) a simple robust control is given for guaranteeing uniform ultimate boundedness of tracking errors for n-link robot manipulators. It is pointed out here that an equally simple control law, which is also continuous in nature, can guarantee global exponential stability of tracking errors under the same set of conditions.<> View full abstract»

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  • A class of scheduling policies for mixed data with renewal arrival processes

    Publication Year: 1993 , Page(s): 455 - 459
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    Two mutually independent traffic streams whose arrivals are modeled as renewal processes are considered. The arrivals are stored in an infinite capacity buffer. One of the processes requires a strict upper bound on the total delay per arrival, and it is assumed that the processing time per arrival for both processes is a constant. Given the above model, the class of nonpreemptive scheduling policies which satisfy the delay constraint while maintaining the system stability is found. The delays induced by the latter policy are analyzed via a methodology based on the regenerative theorem. A numerical example is given in which the policy that minimizes the expected delays for both traffic streams is also considered View full abstract»

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  • Continuity properties of the real/complex structured singular value

    Publication Year: 1993 , Page(s): 415 - 428
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1004 KB)  

    The structured singular-value function (μ) is defined with respect to a given uncertainty set. This function is continuous if the uncertainties are allowed to be complex. However, if some uncertainties are required to be real, then it can be discontinuous. It is shown that μ is always upper semi-continuous, and conditions are derived under which it is also lower semi-continuous. With these results, the real-parameter robustness problem is reexamined. A related (although not equivalent) problem is formulated, which is always continuous, and the relationship between the new problem and the original real-μm problem is made explicit. A numerical example and results obtained via this related problem are presented View full abstract»

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  • Adaptive robotic visual tracking: theory and experiments

    Publication Year: 1993 , Page(s): 429 - 445
    Cited by:  Papers (124)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1364 KB)  

    The use of a vision sensor in the feedback loop is addressed within the controlled active vision framework. Algorithms are proposed for the solution of the robotic (eye-in-hand configuration) visual tracking and servoing problem. Visual tracking is stated as a problem of combining control with computer vision. The sum-of-squared differences optical flow is used to compute the vector of discrete displacements. The displacements are fed to an adaptive controller (self-tuning regulator) that creates commands for a robot control system. The procedure is based on the online estimation of the relative distance of the target from the camera, but only partial knowledge of the relative distance is required, obviating the need for offline calibration. Three different adaptive control schemes have been implemented, both in simulation and in experiments. The computational complexity and the experimental results demonstrate that the proposed algorithms can be implemented in real time View full abstract»

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  • On the existence and uniqueness of solutions in adaptive control systems

    Publication Year: 1993 , Page(s): 474 - 479
    Cited by:  Papers (54)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    The issue of existence and uniqueness of solutions, which arises in the analysis of adaptive control systems, is investigated. Sufficient conditions that guarantee existence and uniqueness in positive time of solutions to differential equations describing a wide class of adaptive schemes are given. The concept of Filippov's solution is introduced as a method of dealing with discontinuous adaptive systems View full abstract»

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  • Simultaneous stabilization of single-input single-output discrete time systems

    Publication Year: 1993 , Page(s): 446 - 450
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB)  

    The problem of finding one compensator which simultaneously stabilizes a family of single-input-single-output (SISO) discrete-time plants is considered. The family of plants is described by the transfer functions {Pz, q): qQ}, which are generated via a z-transformation. A number of assumptions describing the set of allowable plants are then given. These assumptions include some regularity conditions on the plants and a minimum-phase requirement. The satisfaction of these assumptions guarantees the existence of a strictly proper stable compensator C(z) for simultaneous stabilization. An iterative computation method is provided for control design View full abstract»

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  • Optimal flow control allocation policies in communication networks with multiple message classes

    Publication Year: 1993 , Page(s): 390 - 403
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1044 KB)  

    Flow control is considered for M(⩾2) transmitting stations sending packets to a single receiver over a slotted time-multiplexed link. The optimal allocation problem is generalized to the case of nonidentical holding costs at the M transmitters. Qualitative properties of optimal discounted and time-average policies that reduce the computational complexity of the M-dimensional optimal flow control algorithm are derived. For M=2, a simple relationship between optimal allocations for states x and x +ei (i=1,2) that leads to significant computational savings in the optimal algorithm is established View full abstract»

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  • An adaptation rate upper limit for adaptive control under model order mismatch

    Publication Year: 1993 , Page(s): 508 - 510
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    An upper limit on the adaptation rate of an adaptive control algorithm when there exists model order mismatch is given. Under the condition that an operator H2 is strictly positive real (SPR), the adaptive control algorithm is stable for a sufficient small estimation rate ∈. An upper limit for ∈ is explicitly given View full abstract»

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  • A comment on `An inequality for the trace of matrix product' by J.K. Baksalary and S. Puntanen

    Publication Year: 1993 , Page(s): 510 - 511
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    An example is provided which illustrates that the new bounds for the trace of the product of an arbitrary n×n real matrix A and an n×n nonnegative definite real symmetric matrix B derived in the above-titled paper (ibid., vol.37, no.2, pp.239-240, Feb. 1992) are not valid View full abstract»

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  • Robustness analysis with correlated highly structured complex uncertainties

    Publication Year: 1993 , Page(s): 480 - 482
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    It is shown that the results reported by the author (ibid., vol.35, no.3, pp.350-352, Mar. 1990) on robustness analysis with highly structured independent perturbations is directly extendable to the case of correlated perturbations. A direct consequence of this extension is that the phase-sensitive structured singular value and the multiloop phase margin can be computed exactly View full abstract»

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  • Minimal periodic realizations of transfer matrices

    Publication Year: 1993 , Page(s): 462 - 466
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    Periodic controllers designed based on the so-called lifting technique are usually represented by transfer matrices. Real operations require that the controllers be implemented as periodic systems. The problem of realizing an Nno×Nni proper rational transfer matrix as an ni-input no-output N-periodic discrete-time system is studied. An algorithm for obtaining periodic realizations which have a minimal number of states is proposed. The result can also be used to remove any redundant states that exist in a periodic system View full abstract»

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  • Design of stable controllers attaining low Hinfinity weighted sensitivity

    Publication Year: 1993 , Page(s): 485 - 488
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    Strong stabilization and sensitivity reduction for a linear time-invariant single-input single-output system are considered. Stable controllers are practically desirable in the presence of possible actuator or sensor failures. It is verified precisely that the optimal controller of Hinfinity weighted sensitivity minimization is almost always unstable when the plant has more than two zeros in the right-half plane. An algorithm for attaining the low sensitivity property for stable controllers is presented. It is based on Nevanlinna-Pick interpolation. View full abstract»

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  • Application of Kharitonov's theorem to mechanical systems

    Publication Year: 1993 , Page(s): 488 - 491
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    Kharitonov's theorem is used to derive a robust stability condition for proportional-integral-derivative (PID)-controlled multi-degree-of-freedom mechanical systems. The characteristic equation of such a system is given as a determinant of a third-order polynomial with matrix coefficients from which a scalar interval polynomial is obtained. A simple procedure for designing PID controllers for these mechanical systems is described, and a new Kharitonov-like result which states roughly that a controller designed for an upper bounding inertia matrix results in stable set-point regulation for all other inertias is proved View full abstract»

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  • Output feedback eigenstructure assignment using two Sylvester equations

    Publication Year: 1993 , Page(s): 495 - 499
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB)  

    The eigenstructure assignment problem with output feedback is studied for systems satisfying the condition p+m> n. The main tool used is the concept of (C, A, B)-invariance and two coupled Sylvester equations, the solution of which leads to the computation of an output stabilizing feedback. A computationally efficient algorithm for the solution of these two coupled equations, which leads to the computation of a desired output feedback, is presented View full abstract»

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  • An algorithm for simultaneous stabilization using decentralized constant gain output feedback

    Publication Year: 1993 , Page(s): 450 - 455
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    An algorithm which solves, numerically, the simultaneous stabilization problem using a constant gain decentralized control law is presented. The algorithm is determined from the necessary conditions for minimizing an optimal control problem. The optimal control problem consists of n plant models each with its own cost function. The costs are summed to create an average cost function and equality constraints are added to yield the decentralized control structure. The algorithm can start with any stabilizing full state feedback gain for each model and will converge to the optimal constant feedback gain for all models assuming a solution exists. Examples of the algorithm are given for Kharitonov synthesis and optimal gain scheduled control law synthesis using output feedback View full abstract»

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  • Finite-dimensional adaptive observers applied to distributed parameter systems

    Publication Year: 1993 , Page(s): 469 - 474
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (564 KB)  

    The application of finite-dimensional adaptive observers to distributed parameter systems is addressed. Ultimate boundedness of the parameter and state errors are proved in the case of residuals which have finite energy over a finite time interval, provided the plant input is definitely exciting. In the absence of definite excitation, an error growth rate of proportional to t1/2 is proved. The results are obtained without assuming plant stability or input boundedness View full abstract»

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  • H analysis and synthesis of discrete-time systems with time-varying uncertainty

    Publication Year: 1993 , Page(s): 459 - 462
    Cited by:  Papers (46)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    The problems of H analysis and synthesis of discrete-time systems with block-diagonal real time-varying uncertainty are considered. It is shown that these problems can be converted into scaled H analysis and synthesis problems. The problems of quadratic stability analysis and quadratic stabilization of these types of systems are dealt with as a special case. The results on synthesis are established for general linear dynamic output feedback control View full abstract»

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  • Input-output structure of linear differential/algebraic systems

    Publication Year: 1993 , Page(s): 404 - 414
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (892 KB)  

    The problem of describing the input-output structure of general linear differential/algebraic systems is addressed. Explicit formulas are given in terms of the original parameters for systems with an arbitrary amount of redundancy. These formulas allow one to establish whether the system determines an input-output relation at all, and if so, they describe the rank of the transfer matrix and its pole/zero structure at infinity. The formulas may be seen as generalizations of a number of classical results on the input-output structure of standard state-space systems and descriptor systems, satisfying certain constraints. For the derivation, the pencil representation rather than the descriptor representation is used View full abstract»

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  • Compensator design for stability enhancement with collocated controllers: explicit solutions

    Publication Year: 1993 , Page(s): 505 - 507
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB)  

    The author (ibid., vol.36, no.9, pp.994-1007, Sept. 1991) formulated and solved an optimal linear quadratic Gaussian (LQG) problem for stability enhancement for flexible structures with collocated controllers and constructed an approximate realization of the compensator. An explicit closed-form solution for the compensator transfer function is obtained here. It is positive real but nonrational View full abstract»

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  • Exponential observers for nonlinear systems

    Publication Year: 1993 , Page(s): 482 - 484
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    Exponentially converging observers are exhibited for a large class of multi-input multi-output (MIMO) nonlinear systems. Potential applications of these observers to mechanical systems and distillation columns are presented View full abstract»

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  • Singular-perturbation of the time-optimal soft-constrained cheap-control problem

    Publication Year: 1993 , Page(s): 466 - 469
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    The solution of a time-optimal soft-constrained control problem with linear dynamics is considered. The cost function has no penalty on the integral of the state. The solution is formulated in terms of the controllability Grammian and is obtained as the solution of a system of linear algebraic equations and a nonlinear scalar algebraic equation. As the state approaches the origin, or equivalently, as the control becomes cheap, the optimal final time becomes small. This introduces a highly degenerate hierarchy of amplitude scales. An approach based solely on expanding the controllability Grammian is developed to obtain an asymptotic solution of the problem without resorting to boundary-layer theory View full abstract»

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  • Hautus-type conditions for controllability of implicit linear discrete-time systems revisited

    Publication Year: 1993 , Page(s): 502 - 505
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    New simple proofs of validity of Hautus-type conditions for controllability of (not necessarily regular) implicit linear discrete-time systems are given. The new proofs do not require any previous knowledge of implicit systems theory View full abstract»

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  • The queueing equivalence to a manufacturing system with failures

    Publication Year: 1993 , Page(s): 499 - 502
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (388 KB)  

    The authors consider optimal production rate control in a failure prone manufacturing system. It is well known that the hedging point policy is the optimum controller for such a system. They show that under the hedging point policy the system can be treated as an M/M/1 queue. Therefore, existing results in queuing theory can be readily applied to obtaining the steady-state probability density function of the production surplus, based on which the optimal hedging point policy can be computed. To a large extent, the approach is based on sample path analysis. It not only provides an alternative way to solve the problem but also reveals some interesting insights View full abstract»

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  • A comparison of adaptive and nonadaptive feedback for discrete-time plants with dead time

    Publication Year: 1993 , Page(s): 492 - 495
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    The control of plants with unknown dead time and parameters is considered. The goal of control is to stabilize plant output at a given level. The performance of the optimal, nonadaptive algorithm in the case of uncertain knowledge of parameters is evaluated and compared with that of the adaptive algorithm proposed here. The effective regions for both algorithms are evaluated. Simulation results confirming the efficiency of the adaptive algorithm and the performance estimates are presented View full abstract»

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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

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Meet Our Editors

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