Showing papers in "Systems & Control Letters in 1986"

TL;DR: In this paper, local bifurcation control problems are defined and employed in the study of the local feedback stabilization problem for nonlinear systems in critical cases, and sufficient conditions are obtained for the local stabilizability of general nonlinear system whose linearizations have a pair of simple, nonzero imaginary eigenvalues.

TL;DR: In this paper, the concepts of real and complex stability radii are introduced and some properties of their properties discussed, including their properties in terms of stability and their properties of stability.

TL;DR: In this paper, the authors generalize the notion of stability radius introduced in [1] to allow for structured perturbations and relate the stability radius to the existence of Hermitian solutions of an algebraic Riccati equation.

TL;DR: In this article, a feedback invariant set of integers is associated with any nonlinear multivariable system which is linear with respect to the inputs: it is shown to be the set of controllability indices of the largest feedback linearizable subsystem, i.e. the largest subsystem which can be made locally linear and controllable by means of nonsingular feedback transformations.

TL;DR: In this article, an adaptive control system of the type considered earlier by the author, which was designed to be stable under the assumption that the unknown plant parameters are constant, is shown to maintain stability when the plant parameters were slowly time varying.

TL;DR: In this article, a new conceptual framework employing differential algebra is proposed for solving the long-standing problem of inverting nonlinear input-output differential systems, which rest upon an invariant integer which, for constant linear systems, turns out to be the rank of the transfer matrix.

TL;DR: In this article, the necessary and sufficient conditions for nonlinear deterministic and stochastic systems which can be immersed into linear observable ones are identified by necessary and necessary conditions, which generalize earlier results in both cases.

TL;DR: In this paper, the authors develop output reachability characterizations of linear finite dimensional multivariate systems, so as to translate excitation properties of system inputs to excitation property of system outputs, states, or associated regression vectors.

TL;DR: The problem of robustly stabilizing an infinite dimensional system with transfer function G, subject to an additive perturbation Δ is considered in this paper, where it is shown that G ϵ B 0(σ) of systems introduced by Callier and Desoer [3] is stabilizable if and only if ϵ ⩽ σ min (G ∗ 1 ) ( = the smallest Hankel singular value of G ∗ ).

TL;DR: In this article, it was shown that in the problem of uniformly (or H∞−) optimal control of linear time-invariant plants, arbitrary nonlinear, time-varying controllers offer no advantage over linear, time invariant controllers.

TL;DR: It is proved that least-squares algorithms enjoy strong optimality properties, and that these properties do not hold for other frequently used projection algorithms, such as least-absolute-values or minimax algorithms, corresponding to a description of the measurement error in h or l∞ norm, respectively.

TL;DR: A recursive algorithm is presented to construct a reduced order observer for a given observable descriptor system using the staircase form for generalized state space models.

TL;DR: In this paper, the authors considered a linear quadratic differential game in which the weighting on the minimizing control is allowed to approach zero and showed that if a certain minimum phase condition is satisfied then the value of the game will approach zero.

TL;DR: In this paper, the Schur-Cohn stability test for polynomials with complex coefficients was extended to polynomial with complex polynomorphisms, which is based on a three-term recursion of a conjugate symmetric sequence of polynoms.

TL;DR: In this article, new criteria for the analysis of structural controllability and observability are derived for systems where additional structure in the parameter variations is taken into consideration, and existing results are shown to be generalized in this way.

TL;DR: In this paper, the conic sector analysis of the closed-loop stability and robustness of a multivariable-analog-system controller based on sampled-data feedback compensation is investigated.

TL;DR: In this paper, the problem of finding a stable rational transfer function G(s) of a MacMillan degree k so as to minimize ∥W(G - G ∥ H) is considered.

TL;DR: In this article, the spectral properties of a Toeplitz + Hankel operator were investigated in the context of the mixed-sensitivity H ∞ -optimization problem and whose largest eigenvalue characterizes the optimal achievable performance ϵ 0.

TL;DR: In this paper, the approximation error involved in the optimal Hankel-norm approximation procedure was shown to differ from those arising in the unweighted optimal HN approximation procedure by a multiplicative factor depending solely on the weighting function.

TL;DR: In this paper, the Taylor-series expansion of the output function of a nonlinear system is used to give a preliminary account on the notion of right-invertibility of nonlinear systems.

TL;DR: In this article, the authors dealt with a discontinuous control system that consists of two finite-dimensional linear systems; the first describes the motion in a given half-space, the second in the complementary half-Space Necessary and sufficient conditions for local controllability are obtained.

TL;DR: In this paper, the geometric structure of two subsets of the parameter space that are of interest in the context of adaptive LQ-control is studied. And the main result is that these sets are $C^\omega$-manifolds.

TL;DR: In this article, a nonlinear generalization of Silverman's structure algorithm is proposed for inverting input-output systems, and the connection with the problem of inverting inputs and outputs is briefly described.

TL;DR: In this paper, the sign-sign variant of the LMS algorithm with and without leakage is investigated, and three basic questions are considered through simplistic examples: the need to redefine input excitations for parameter convergence, the influence of designer-selected variables on offset due to leakage, and the effect of measurement noise in underexcited systems.

TL;DR: In this paper, nonlinear averaging theorems for two-time scale systems are presented, where the dynamics of the fast system are allowed to vary with the slow system, and estimates of the parameter convergence rates are obtained which do not rely on a linearization of the system around the equilibrium.

TL;DR: In this paper, a general class of strongly block D -stable matrices is introduced, and a new concept of strong block D-stability is introduced. But this concept is not applicable to the singular perturbation problem.

TL;DR: In this paper, a simulation of an adaptive control system with a single unknown pole and constant disturbance at the input is presented, and it is shown that the system in fact undergoes bifurcations and exhibits rich dynamics.

TL;DR: In this paper, it was shown that in the adaptive LQ control problem this does not at all lead to an easier problem, and that in adaptive control problems one may drop the requirement of identifying the true system in order to simplify the problem of control.

TL;DR: In this article, the authors proposed a direct control scheme based on the Vasil'eva boundary layer functions (VLF) method for nonlinear optimal control problems, which consists in directly expanding the problem's conditions into postulated asymptotic series and then in successively solving lower-dimensional approximate decomposition problems of optimal control.

TL;DR: In this paper, necessary and sufficient conditions for the existence of a positive definite solution to the algebraic Riccati equation are given, and it is shown that when such a solution exists, it is either unique, or there are uncountably many such solutions.