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Automatic Control, IEEE Transactions on

Issue 1 • Date Jan 1989

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Displaying Results 1 - 21 of 21
  • Linearization of discrete-time nonlinear systems and a canonical structure

    Page(s): 119 - 122
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    Linearizable nonlinear discrete-time systems are described as a composition of diffeomorphisms. Linearizability of a general nonlinear system is obtained as an extension of linearizability of the system expressed in terms of the diffeomorphisms View full abstract»

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  • Convolution and Hankel operator norms for linear systems

    Page(s): 94 - 97
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    Some norms are derived for convolution and Hankel operators associated with linear, time-invariant systems. In certain cases, these norms are shown to be identical. The tightest possible bound has been obtained for the absolute magnitude of the Euclidean 2 or ∞ norm of the time-domain response of a multioutput system to certain classes of input disturbance View full abstract»

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  • Constrained optimal control

    Page(s): 122 - 126
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    The explicit form of the optimal control law of a given linear, discrete-time, time-invariant process subject to a quadratic cost criterion is well known. In some applications it is desirable that the state of a controlled dynamic process be nonnegative, given a certain class of initial disturbances. Using the controllable block companion transformation, sufficient conditions on the weighting matrices of the cost criterion are derived to ensure that the closed-loop response of the original process with the standard, unconstrained optimal feedback law will be nonnegative. It is shown that the nondiagonal elements of the transformed weighting matrices can be chosen to ensure nonnegativity View full abstract»

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  • A Nyquist stability criterion for distributed parameter systems

    Page(s): 90 - 92
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    A Nyquist graphical stability criterion is developed for distributed parameter, possible unstable, single-loop systems. Practical conditions are presented for existence, uniqueness, causality, and asymptotic or exponential stability of the closed-loop impulse response. The hypotheses are given for the transfer function only and do not require any knowledge of its time-domain impulse response View full abstract»

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  • Matrix inequalities applicable to estimating solution sizes of Riccati and Lyapunov equations

    Page(s): 97 - 98
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    Simultaneous summation upper bounds for the eigenvalues of the matrix product XY are presented, where X, Y ε Rnxn, with Y symmetric and X arbitrary. These bounds are a generalization of tr (XY) bounds; the requirements on Y are relaxed, and the bound for tr (XY) is stronger than those shown in the literature View full abstract»

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  • On the structure of the time-optimal controls for robotic manipulators

    Page(s): 115 - 116
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    An alternative proof is presented of the fact that the time-optimal controls for (rigid) robotic manipulators can never be singular simultaneously View full abstract»

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  • Distributed iterative aggregation algorithms for box-constrained minimization problems and optimal routing in data networks

    Page(s): 34 - 46
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1040 KB)  

    A gradient-projection algorithm using iterative aggregation and disaggregation is proposed and analyzed for box-constrained minimization problems. In a distributed computation model, the algorithm is shown to converge. The algorithm is applied to optimal routing in a large interconnected data communication network, resulting in a multilevel hierarchical clustering that naturally fits the hierarchical topological structure of such networks. An implementation of the algorithm for a 52-node network shows that the serial version of the algorithm has a saving of 35% of the computational time as compared to a path-formulated gradient-projection code that is among the fastest existing programs for path-formulated optimal routing View full abstract»

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  • On-line sensitivity analysis of Markov chains

    Page(s): 76 - 86
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    Discrete-event systems modeled as continuous-time Markov processes and characterized by some integer-valued parameter are considered. The problem addressed is that of estimating performance sensitivities with respect to this parameter by directly observing a single sample path of the system. The approach is based on transforming the nominal Markov chain into a reduced augmented chain, the stationary-state probabilities which can be easily combined to obtain stationary-state probability sensitivities with respect to the given parameter. Under certain conditions, the reduced augmented chain state transitions are observable with respect to the state transitions of the system itself, and no knowledge of the nominal Markov-chain state of the transition rates is required. Applications for some queueing systems are included. The approach incorporates estimation of unknown transition rates when needed and is extended to real-valued parameters View full abstract»

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  • A quick simulation method for excessive backlogs in networks of queues

    Page(s): 54 - 66
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (940 KB)  

    Excessive backlogs in stable open Jackson networks are studied. Although these events occur rarely, they can be critical, since they can impair the functioning of the network. The use of simulation to estimate their probability is attempted. Since a direct simulation of a rare event takes a very long time, a method is discussed for changing the network to speed up the simulation, using a heuristic method. It is shown by examples that the method can be several orders of magnitude faster than direct simulations View full abstract»

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  • New matching conditions for output regulation of a class of uncertain nonlinear systems

    Page(s): 116 - 119
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    Some sufficient conditions for the structure of modelling uncertainties for output regulation of uncertain systems are presented. It turns out that these conditions include as special cases the ordinary matching conditions for state regulation of uncertain systems and the disturbance decoupling condition. The previous restrictions on the structure of modelling uncertainties can be considerably relaxed in the case of output regulation. The significance of the result is shown by a simple example View full abstract»

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  • Computing the transmission zeros of large space structures

    Page(s): 92 - 94
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    The transmission zeros of a large space structure are frequently computed by means of the general-purpose algorithm of A. Emami-Naeini and P. Van Dooren (1982). It is shown that careful exploitation of the special form of the equations of motion of structural dynamics leads to an algorithm that is at least 60 times as fast as this when applied to an undamped structure, and 15 times as fast for a lightly damped one View full abstract»

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  • On the force control problem for flexible joint manipulators

    Page(s): 107 - 111
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (468 KB)  

    It is shown, using a singular perturbation model of the elastic joint manipulator dynamics and the concept of corrective control. how force control techniques developed for rigid manipulators can be extended to the flexible joint case. It is shown that the overall control law can be implemented in an inner loop/outer loop structure, where the inner loop is a nonlinear control that linearizes the system restricted to a suitable integral manifold in state space and the outer loop is a linear control that can be designed independently of the nonlinear inner loop, using any number of force control schemes designed for rigid manipulators to extend all of the standard techniques for force control of rigid manipulators to the flexible joint case, including hybrid position/force control, impedance control, or any other suitable design View full abstract»

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  • Some tractable supervisory control problems for discrete-event systems modeled by Buchi automata

    Page(s): 10 - 19
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (980 KB)  

    Discrete-event systems (DES) are modeled by Buchi automata together with a means of online control. In this setting the concept of a controllable language is extended to infinite strings, and conditions for the existence of a supervisor (controller) to implement a prescribed closed-loop behavior are derived. The focus is on a class of DES called product systems. These are DES composed of a finite set of asynchronous components. A control problem for such a system typically requires the synthesis of an online controller so as to achieve some prescribed coordinated behavior of the component subsystems. One of the principal difficulties in this task is that the size of the state space increases exponentially with the number of components. It is shown that despite this fact several interesting control synthesis problems for such systems are computationally feasible, and algorithms are developed for solution View full abstract»

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  • Singular perturbation in piecewise-linear systems

    Page(s): 87 - 90
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    A singular perturbation technique is developed that allows for a decoupling of a continuous piecewise-linear system into slow and fast subsystems. Under the assumption of asymptotic stability, the fast variable is found to decay in the boundary layer to its quasi-steady-state solution, which is given by a continuous implicit function of the slow variable. The solution is found using a finite step algorithm. Sufficient conditions for the approximation to be accurate to an order of O(μ), where μ is a parameter of the system, are given. The technique is illustrated by a numerical example View full abstract»

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  • A method of control system design using global search

    Page(s): 111 - 115
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB)  

    A method is presented that eliminates the problem of the conventional quadratic performance criterion not being effective for some real-world systems because the performance parameters are seldom related to meaningful quantities. Globally searching the performance index allows the index to have local minimums as well as discontinuities, so it can be defined in meaningful terms. This ability to define meaningful performance indexes potentially can reduce the design time and produce better controls for nonlinear systems. The method has been implemented and tested with a simulated nonlinear system. Comparison to optimal control theory shows that the methodology has merit. Gains occur because the controller can be nonlinear and the system can be efficiently optimized to have the desired characteristics View full abstract»

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  • Convergence of gradient projection routing methods in an asynchronous stochastic quasi-static virtual circuit network

    Page(s): 20 - 33
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    The convergence of the gradient projection algorithms for optimal routing in virtual circuit data networks proposed by D.P. Bertsekas (1982) is studied. The routing model explicitly takes into account stochastic generation and termination of virtual circuits, distributed asynchronous routing updates, inaccurate flow measurement, and delays in forwarding control packets. The problem of assigning paths for incoming sessions (or virtual circuits) to implement the gradient projection algorithms is also studied. A metering rule based on deficiency in a desired number of virtual circuits is proposed and analyzed. It is shown that the proposed metering rule is better than a randomized rule in some sense. The gradient projection routing algorithms implemented either by the metering rule or the randomized rule are shown to converge to a neighborhood of a long-term optimal routing View full abstract»

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  • Exact solutions to some minimum-time problems and their behavior near inequality state constraints

    Page(s): 103 - 106
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (388 KB)  

    A heuristic method for generating exact solutions to certain minimum-time problems with inequality state constraints is used to generate solutions to a class of path-planning problems. It is observed that, when the state constraint function has a continuous second derivative, the constraint does not become active for any continuous-time period. Instead, the solution bumps up against the constraint repeatedly at isolated points. The solution method offers some insight into this behavior. It is shown that such a state constraint can become active for a continuous-time period only if the solution path satisfies an overdetermined system of equations. It is argued that the phenomenon is general and will arise in many different optimization problems View full abstract»

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  • Performance evaluation of job-shop systems using timed event-graphs

    Page(s): 3 - 9
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (676 KB)  

    Timed event-graphs, a special class of timed Petri nets, are used for modelling and analyzing job-shop systems. The modelling allows the steady-state performance of the system to be evaluated under a deterministic and cyclic production process. Given any fixed processing times, the productivity (i.e., production rate) of the system can be determined from the initial state. It is shown in particular that, given any desired product mix, it is possible to start the system with enough jobs in process so that some machines will be fully utilized in steady-state. These machines are called bottleneck machines, since they limit the throughput of the system. In that case, the system works at the maximal rate and the productivity is optimal. The minimal number of jobs in process allowing optimal functioning of the system is further specified as an integer linear programming problem. An efficient heuristic algorithm is developed to obtain a near-optimal solution View full abstract»

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  • Optimal dynamic scheduling in Jackson networks

    Page(s): 47 - 53
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    A Jackson-like network that supports J types of interactive traffic (e.g., interactive messages) as well as I types of noninteractive traffic (e.g., file transfers, facsimile) is considered. The service-time distributions and the internal routing are homogeneous for all traffic types but can be node (queue) dependent. The problem is to find a scheduling control that minimizes a weighted sum of the average end-to-end delay for the interactive types and at the same time ensures that the average end-to-end delays for the interactive types will be below given design constraints. Conservation laws are first established and shown to yield the base of a polymatroid. The optimal control problem is then transformed into a linear program with the feasible region being the polymatroid base truncated by delay constraints. An optimal control is identified that partitions the traffic types into I+r (0⩽rJ) ordered groups and applies a strict priority rule among the groups. An algorithm is developed that does the grouping and solves the optimization problem. A decentralized implementation of the optimal control is also discussed View full abstract»

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  • Optimal service assignment in a finite-source queue

    Page(s): 67 - 75
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    A dynamic scheduling problem is considered for a finite-source M/M/1 system with several types of customers. A preemptive service-assignment policy is found that maximizes the expected present value of rewards received minus costs incurred over an infinite planning horizon. A policy that always selects customers according to a fixed priority order is called an index policy. It is shown that, when all the average thinking times are the same, there exists an index policy that is optimal over the class of policies considered, which contains policies that are not index policies View full abstract»

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  • Linear periodic systems: eigenvalue assignment using discrete periodic feedback

    Page(s): 99 - 103
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    The eigenvalue assignment problem of a T-periodic linear system using discrete periodic state feedback gains is discussed. For controllable systems, an explicit formula for the feedback law is given that can be used for the arbitrary assignment of the eigenvalues of Φc1(T,0), the closed-loop state transition matrix from 0 to T. For the special case of periodic systems controllable over one period, this control law can be used to obtain any desired Φc1(T,0) View full abstract»

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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

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Meet Our Editors

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