By Topic

Automatic Control, IEEE Transactions on

Issue 4 • Date April 2012

Filter Results

Displaying Results 1 - 25 of 36
  • Table of contents

    Page(s): C1 - C4
    Save to Project icon | Request Permissions | PDF file iconPDF (40 KB)  
    Freely Available from IEEE
  • IEEE Control Systems Society

    Page(s): C2
    Save to Project icon | Request Permissions | PDF file iconPDF (38 KB)  
    Freely Available from IEEE
  • Scanning the issue

    Page(s): 813 - 814
    Save to Project icon | Request Permissions | PDF file iconPDF (37 KB)  
    Freely Available from IEEE
  • Near Optimal Power and Rate Control of Multi-Hop Sensor Networks With Energy Replenishment: Basic Limitations With Finite Energy and Data Storage

    Page(s): 815 - 829
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5662 KB) |  | HTML iconHTML  

    Renewable energy sources can be attached to sensor nodes to provide energy replenishment for extending the battery life and prolonging the overall lifetime of sensor networks. For networks with replenishment, conservative energy expenditure may lead to missed recharging opportunities due to battery capacity limitations, while aggressive usage of energy may result in reduced coverage or connectivity for certain time periods. Thus, new power allocation schemes need to be designed to balance these seemingly contradictory goals, in order to maximize sensor network performance. In this paper, we study the problem of how to jointly control the data queue and battery buffer to maximize the long-term average sensing rate of a wireless sensor network with replenishment under certain QoS constraints for the data and battery queues. We propose a unified algorithm structure and analyze the performance of the algorithm for all combinations of finite and infinite data and battery buffer sizes. We also provide a distributed version of the algorithm with provably efficient performance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Input to State Stabilizing Controller for Systems With Coarse Quantization

    Page(s): 830 - 844
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (516 KB) |  | HTML iconHTML  

    We consider the problem of achieving input-to-state stability (ISS) with respect to external disturbances for control systems with quantized measurements. Quantizers considered in this paper take finitely many values and have an adjustable “center” and “zoom” parameters. Both the full state feedback and the output feedback cases are considered. Similarly to previous techniques from the literature, our proposed controller switches repeatedly between “zooming out” and “zooming in.” However, here we use two modes to implement the “zooming in” phases, which allows us to attenuate an unknown disturbance while using the minimal number of quantization regions. Our analysis is trajectory-based and utilizes a cascade structure of the closed-loop hybrid system. We further show that our method is robust to modeling errors using a specially adapted small-gain theorem. The main results are developed for linear systems, but we also discuss their extension to nonlinear systems under appropriate assumptions. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On a Class of Hierarchical Formations of Unicycles and Their Internal Dynamics

    Page(s): 845 - 859
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1119 KB) |  | HTML iconHTML  

    This paper studies a class of hierarchical formations for an ordered set of n + 1 unicycle robots: the first robot plays the role of the leader and the formation is induced through a constraint function F, so that the position and orientation of the ith robot depends only on the pose of the preceding ones. We study the dynamics of the formation with respect to the leader's reference frame by introducing the concept of reduced internal dynamics, we characterize its equilibria and provide sufficient conditions for their existence. The discovered theoretical results are applied to the case in which the constraint F induces a formation where the ith robot follows a convex combination of the positions of the previous i - 1 vehicles. In this case, we prove that if the curvature of the leader's trajectory is sufficiently small, the positions and orientations of the robots, relative to the leader's reference frame, are confined in a precise polyhedral region. View full abstract»

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

    Page(s): 860 - 874
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3847 KB) |  | HTML iconHTML  

    This paper focuses on the problem of robust experiment design, i.e., how to design an input signal which gives relatively good estimation performance over a large number of systems and model structures. Specifically, we formulate the robust experiment design problem utilizing fundamental limitations on the variance of estimated parametric models as constraints. Using this formulation we design an input signal for situations where only diffuse a priori information is known about the system. Furthermore, we present a robust version of the unprejudiced optimal input design problem. To achieve this, we first develop a closed form solution for the input spectrum which minimizes the maximum weighted integral of the variance of the frequency response estimate over all model structures. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dynamic Quantization of Nonlinear Control Systems

    Page(s): 875 - 888
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (711 KB) |  | HTML iconHTML  

    This paper addresses a problem of finding an optimal dynamic quantizer for nonlinear control subject to discrete-valued signal constraints, i.e., to the condition that some signals must take a value on a discrete and countable set at each time instant. The quantizers to be studied are in the form of a nonlinear difference equation which maps continuous-valued signals into discrete-valued ones. They are evaluated by a performance index expressing the difference between the resulting quantized system and the unquantized system, in terms of the input-output relation. In this paper, we present a closed-form solution, which globally minimizes the performance index. This result shows the performance limitation of a general class of dynamic quantizers. In addition to this, some results on the structure and the stability are given in order to clarify the mechanism of the best dynamic quantization in nonlinear control systems. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Circumnavigation Using Distance Measurements Under Slow Drift

    Page(s): 889 - 903
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1063 KB) |  | HTML iconHTML  

    Consider an agent A at an unknown location, under going sufficiently slow drift, and a mobile agent B that must move to the vicinity of and then circumnavigate A at a prescribed distance from A. In doing so, B can only measure its distance from A, and knows its own position in some reference frame. This paper considers this problem, which has applications to surveillance and orbit maintenance. In many of these applications it is difficult for B to directly sense the location of A, e.g. when all that B can sense is the intensity of a signal emitted by A. This intensity does, however provide a measure of the distance. We propose a nonlinear periodic continuous time control law that achieves the objective using this distance measurement. Fundamentally, a) B must exploit its motion to estimate the location of A, and b) use its best instantaneous estimate of where A resides, to move itself to achieve the circum navigation objective. For a) we use an open loop algorithm formulated by us in an earlier paper. The key challenge tackled in this paper is to design a control law that closes the loop by marrrying the two goals. As long as the initial estimate of the source location is not coincident with the intial position of B, the algorithm is guaranteed to be exponentially convergent when A is stationary. Under the same condition, we establish that when A drifts with a sufficiently small, unknown velocity, B globally achieves its circumnavigation objective, to within a margin proportional to the drift velocity. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Distributed Seeking of Nash Equilibria With Applications to Mobile Sensor Networks

    Page(s): 904 - 919
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (862 KB) |  | HTML iconHTML  

    We consider the problem of distributed convergence to a Nash equilibrium in a noncooperative game where the players generate their actions based only on online measurements of their individual cost functions, corrupted with additive measurement noise. Exact analytical forms and/or parameters of the cost functions, as well as the current actions of the players may be unknown. Additionally, the players' actions are subject to linear dynamic constraints. We propose an algorithm based on discrete-time stochastic extremum seeking using sinusoidal perturbations and prove its almost sure convergence to a Nash equilibrium. We show how the proposed algorithm can be applied to solving coordination problems in mobile sensor networks, where motion dynamics of the players can be modeled as: 1) single integrators (velocity-actuated vehicles), 2) double integrators (force-actuated vehicles), and 3) unicycles (a kinematic model with nonholonomic constraints). Examples are given in which the cost functions are selected such that the problems of connectivity control, formation control, rendezvous and coverage control are solved in an adaptive and distributed way. The methodology is illustrated through simulations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Synchronization of Coupled Oscillators is a Game

    Page(s): 920 - 935
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (854 KB) |  | HTML iconHTML  

    The purpose of this paper is to understand phase transition in noncooperative dynamic games with a large number of agents. Applications are found in neuroscience, biology, and economics, as well as traditional engineering applications. The focus of analysis is a variation of the large population linear quadratic Gaussian (LQG) model of Huang et al. 2007, comprised here of a controlled N-dimensional stochastic differential equation model, coupled only through a cost function. The states are interpreted as phase angles for a collection of heterogeneous oscillators, and in this way the model may be regarded as an extension of the classical coupled oscillator model of Kuramoto. A deterministic PDE model is proposed, which is shown to approximate the stochastic system as the population size approaches infinity. Key to the analysis of the PDE model is the existence of a particular Nash equilibrium in which the agents "opt out' of the game, setting their controls to zero, resulting in the "incoherence' equilibrium. Methods from dynamical systems theory are used in a bifurcation analysis, based on a linearization of the partial differential equation (PDE) model about the incoherence equilibrium. A critical value of the control cost parameter is identified: above this value, the oscillators are incoherent; and below this value (when control is sufficiently cheap) the oscillators synchronize. These conclusions are illustrated with results from numerical experiments. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Stability and Transient Performance of Discrete-Time Piecewise Affine Systems

    Page(s): 936 - 949
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (514 KB) |  | HTML iconHTML  

    This paper considers asymptotic stability and transient performance of discrete-time piecewise affine systems. We propose a procedure to construct a nested sequence of finite-state symbolic models, each of which abstracts the original piecewise affine system and leads to linear matrix inequalities for guaranteed stability and performance levels. This sequence is in the order of decreasing conservatism, and hence gives us the option to pay more computational cost and analyze a finer symbolic model within the sequence in return for less conservative results. Moreover, in the special case where this sequence is finite, an exact analysis of stability and performance is achieved via semidefinite programming. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Exploiting Isochrony in Self-Triggered Control

    Page(s): 950 - 962
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (583 KB) |  | HTML iconHTML  

    Event-triggered control and self-triggered control have been recently proposed as new implementation paradigms that reduce resource usage for control systems. In self-triggered control, the controller is augmented with the computation of the next time instant at which the feedback control law is to be recomputed. Since these execution instants are obtained as a function of the plant state, we effectively close the loop only when it is required to maintain the desired performance, thereby greatly reducing the resources required for control. In this paper we present a new technique for the computation of the execution instants by exploiting the concept of isochronous manifolds, also introduced in this paper. While our previous results showed how homogeneity can be used to compute the execution instants along some directions in the state space, the concept of isochrony allows us to compute the executions instants along every direction in the state space. Moreover, we also show in this paper how to homogenize smooth control systems thus making our results applicable to any smooth control system. The benefits of the proposed approach with respect to existing techniques are analyzed in two examples. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Delay-Independent Stability Test for Systems With Multiple Time-Delays

    Page(s): 963 - 972
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (446 KB) |  | HTML iconHTML  

    Delay-independent stability (DIS) of a general class of linear time-invariant (LTI) multiple time-delay system (MTDS) is investigated in the entire delay-parameter space. Stability of such systems may be lost only if their spectrum lies on the imaginary axis for some delays. We build an analytical approach that requires the inspection of the roots of finite number of single-variable polynomials in order to detect if the spectrum ever lies on the imaginary axis for some delays, excluding infinite delays. The approach enables to test the necessary and sufficient conditions of DIS of LTI-MTDS, technically known as weak DIS, as well as the robust stability of single-delay systems against all variations in delay ratios. The proposed approach, which does not require any parameter sweeping and graphical display, becomes possible by establishing a link between the infinite spectrum and algebraic geometry. Case studies are provided to show the effectiveness of the approach. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimized Dynamic Policy for Receding Horizon Control of Linear Time-Varying Systems With Bounded Disturbances

    Page(s): 973 - 988
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB) |  | HTML iconHTML  

    This paper deals with the problem of reducing the online computational complexity of receding horizon control (RHC) algorithms for a class of linear systems with a polytopic system description and with bounded additive disturbances. We explore a class of admissible polytopic controller dynamics involving a disturbance feedforward term for a dynamic policy which ensures reduced conservativeness and also offers a way to significantly simplify the online computations by allowing the controller dynamics to be optimized offline. Moreover, for a deterministically time-varying system with additive disturbances, we explore the use of the proposed dynamic policy as the terminal control policy appended to a standard finite-horizon disturbance-based RHC policy. We also present results on the stability of the system under the RHC schemes based on the proposed policy, in the context of both the nominal and the (H-based) minmax cost minimizations. Results of simulation studies that illustrate the effective performance and the computational efficiency of the proposed control schemes are included. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Multivariable Adaptive Backstepping Control: A Norm Estimation Approach

    Page(s): 989 - 995
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (372 KB) |  | HTML iconHTML  

    In this note, a novel output-feedback adaptive backstepping control is proposed for linear time-invariant multivariable plants under a mild assumption that the Hurwitz condition for high-frequency gain matrix is satisfied. By estimating the norm of those unknown parameter matrices instead of their elements, it is shown that only one parameter needs to be updated online and therefore, the computational burden can be greatly reduced compared with any current multivariable adaptive control scheme. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High Gain Observer Design for Some Networked Control Systems

    Page(s): 995 - 1000
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    New results on high gain observer design for networked control systems via an emulation-like approach are presented. By using a general framework and a Lyapunov approach, we derive some explicit conditions on the maximum allowable transmission interval that ensure an exponential convergence of the observation error for a large class of network protocols. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Various Ways to Compute the Continuous-Discrete Extended Kalman Filter

    Page(s): 1000 - 1004
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (249 KB) |  | HTML iconHTML  

    The Extended Kalman Filter (EKF) is a very popular tool dealing with state estimation. Its continuous-discrete version (CD-EKF) estimates the state trajectory of continuous-time nonlinear models, whose internal state is described by a stochastic differential equation and which is observed through a noisy nonlinear form of the sampled state. The prediction step of the CD-EKF leads to solve a differential equation that cannot be generally solved in a closed form. This technical note presents an overview of the numerical methods, including recent works, usually implemented to approximate this filter. Comparisons of theses methods on two different nonlinear models are finally presented. The first one is the Van der Pol oscillator which is widely used as a benchmark. The second one is a neuronal population model. This more original model is used to simulate EEG activity of the cortex. Experiments showed better stability properties of implementations for which the positivity of the prediction matrix is guaranteed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Controlled Hopwise Averaging and Its Convergence Rate

    Page(s): 1005 - 1012
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (325 KB) |  | HTML iconHTML  

    This technical note develops Ideal Controlled Hopwise Averaging (ICHA) and Controlled Hopwise Averaging (CHA), two asynchronous distributed averaging algorithms for wireless networks, which attempt to “make the most” out of each iteration by fully exploiting the broadcast nature of wireless medium and incorporating feedback control of when to initiate an iteration. The latter feature, enabled by a common quadratic Lyapunov function, is novel among existing schemes and represents a new way to apply Lyapunov stability theory. We also derive deterministic upper bounds on the exponential convergence rate of ICHA on general and specific graphs, express the bounds explicitly in terms of the graph invariants, and show that they outperform the stochastic convergence rate of Pairwise Averaging on some common graphs of opposing densities. Finally, we obtain upper bounds on the convergence rate of CHA and show that CHA is capable of closely mimicking the behavior of ICHA, while being practical. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Networked Markov Decision Processes With Delays

    Page(s): 1013 - 1018
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (226 KB) |  | HTML iconHTML  

    We consider a networked control system, where each subsystem evolves as a Markov decision process with some extra inputs from other systems. Each subsystem is coupled to its neighbors via communication links over which the signals are delayed, but are otherwise transmitted noise-free. A centralized controller receives delayed state information from each subsystem. The control action applied to each subsystem takes effect after a certain delay rather than immediately. We give an explicit bound on the finite history of measurement and control that is required for the optimal control of such networked Markov decision processes. We also show that these bounds depend only on the underlying graph structure as well as the associated delays. Thus, the partially observed Markov decision process associated with a networked Markov decision process can be converted into an information state Markov decision process, whose state does not grow with time. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Decentralized Robust Control Invariance for a Network of Storage Devices

    Page(s): 1018 - 1024
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB) |  | HTML iconHTML  

    Robust control of networked storage devices is considered. Each storage device is modeled as a single-state, discrete-time integrator with bounded control input, and subject to additive disturbance. The values of the disturbance are unknown but are assumed to belong to bounded sets. Nodes exchange stored resource through links of limited capacity. Characterization of the maximal robust control invariant (RCI) set is provided and decentralization of the robust feasibility problem is considered. A notion of decentralized RCI set is introduced and a parametrization of a family of decentralized RCI sets is proposed. It is shown that the set of parameters for which the decentralized RCI sets are non-empty is a polyhedral set. The result offers a possibility to use convex optimization for selection of bounds on the admissible flow through the network which ensure feasibility of the proposed decentralized design. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Computation of Zames-Falb Multipliers Revisited

    Page(s): 1024 - 1029
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (611 KB) |  | HTML iconHTML  

    The convex approach to the absolute stability problem is considered. Gapski and Geromel's algorithm for computing Zames-Falb multipliers, used in determining stability, treats the problem as an optimization problem. It is found that their algorithm may terminate prematurely in some cases, failing to find the optimal multiplier. We propose an improvement that always finds an ascent direction and a multiplier that improves the objective function whenever one exists. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Decentralized Control via Gröbner Bases and Variable Elimination

    Page(s): 1030 - 1035
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (237 KB) |  | HTML iconHTML  

    We consider the problem of optimal decentralized controller synthesis. There are several classes of such problems for which effective solution methods are known, including the quadratically invariant one. In this technical note, we use Gröbner bases and elimination theory to characterize all closed-loop maps achievable by forming a feedback loop with decentralized controllers. We show that this approach allows solution of a wide class of optimal decentralized control problems; it includes not only quadratically invariant problems under a technical condition but also some other problems which are not quadratically invariant. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Strict Lyapunov Functions for the Super-Twisting Algorithm

    Page(s): 1035 - 1040
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (339 KB) |  | HTML iconHTML  

    A method to construct a family of strict Lyapunov functions, i.e., with negative definite derivative, for the super-twisting algorithm, without or with perturbations, is provided. This second order sliding modes algorithm is widely used to design controllers, observers and exact differentiators. The proposed Lyapunov functions ascertain finite time convergence, provide an estimate of the convergence time, and ensure the robustness of the finite-time or ultimate boundedness for a class of perturbations wider than the classical ones for this algorithm. Since the Lyapunov functions and their derivatives are quadratic forms, the operation with them is as simple as for linear time invariant systems. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Multiple Model Adaptive Mixing Control: The Discrete-Time Case

    Page(s): 1040 - 1045
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (397 KB) |  | HTML iconHTML  

    Most of the work in multiple model adaptive control with various forms of switching focused on continuous-time systems. The purpose of this technical note is to extend the results of one approach, the adaptive mixing control (AMC), to discrete-time systems. Further, the technical note solves the tracking problem which has not been addressed in most schemes of this class. Stability and robustness properties of the AMC scheme for discrete-time systems are analyzed. It is shown that in the ideal case, when no disturbances or unmodeled dynamics are present, the tracking error converges to zero. In the non ideal case, the mean-square tracking error is of the order of magnitude of the modeling error provided the unmodeled dynamics satisfy a norm-bound condition. While these robustness results are conceptually similar to those of traditional robust adaptive control, the proposed scheme does not suffer from the drawback of stabilizability of the estimated plant and in addition performs much better in simulation studies. Furthermore, it allows well developed results from robust control to be incorporated in the design. 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