Showing papers by "Jie Chen published in 2004"

Miniaturised microstrip bandpass filter using stepped impedance ring resonators

Abstract: A novel microwave bandpass filter using microstrip stepped impedance ring resonators is reported. The new filter has the advantages of compact size together with sharp rejection of outbands. A two-pole microstrip bandpass filter of this type has been implemented and examined, theoretically and experimentally.

Robust stability of quasipolynomials: vertex-type tests and extensions

Abstract: We study the robust stability of uncertain quasipolynomials, whose coefficients may vary in a certain prescribed range. We consider specifically the so-called interval and diamond quasipolynomials, and our goal is to develop vertex- and edge type-conditions for these quasipolynomial families to be robustly stable independent of delay. Moreover, we also present a number of extensions to more general uncertain quasipolynomials, including both frequency-sweeping and vertex/edge type results.

Model invalidation in /spl lscr//sub 1/ using frequency-domain data

Abstract: In this note, we study the problem of invalidating uncertain models with an additive uncertainty. The problem is to check the existence of an uncertainty and a measurement noise which fit to the given model structure and the uncertainty/noise description, as well as the experimental data used for invalidation. We consider a mixed setting in which the uncertainty is characterized in time domain by the /spl lscr//sub 1/ induced system norm, while the available data are frequency response samples of the system. We show that this problem, which by formulation poses an infinite-dimensional primal optimization problem, can be solved in a dual, finite-dimensional space with finitely many constraints.

A novel passive path following controller for a rehabilitation robot

Abstract: In this paper, we present a path generation and control strategy for a robotic manipulator to mimic the dynamics of a continuously reconfigurable anisotropic impedance. Motivated by a nonholonomic kinematic constraint, a dynamic path generator is designed to trace a desired contour in the robot's workspace when an interaction force is applied at the robot's end-effector. The proposed continuous control strategy achieves semi-global asymptotically stable path following for the robot manipulator in the presence of uncertainty in the robot dynamics. Additionally, the path generator also ensures safety by maintaining the desired net flow of energy during the human robot interaction from the user toward the manipulator. In addition to providing asymptotic path following, the control algorithm also ensures sufficiently rapid error convergence at the end-effector such that the actual energy transfer profile follows the desired energy transfer profile - thus rigorously ensuring user safety.

Robust stability of quasipolynomials with commensurate delays

Abstract: In this paper we study the robust stability of uncertain quasipolynomials, whose coefficients are only known to be confined within certain prescribed sets. We consider such quasipolynomials with commensurate delays. We derive a sufficient condition for the uncertain quasipolynomials to be robustly stable independent of delay, when they are confined to the families of interval, diamond, and spherical quasipolynomials. The condition requires checking the robust stability of one polynomial, and computing additionally a frequency-dependent matrix.

Probabilistic bounds for model invalidation assessment

Abstract: This paper is concerned with a mixed deterministic/probabilistic model invalidation problem, which amounts to determining the probability for a given model to reproduce some given experimental data. We consider an additive uncertain model, in which the modelling uncertainty is characterized in time domain by the l/sub 1/ induced system norm. The data available for invalidation are input-output time series and are assumed to have been corrupted by a random noise with Gaussian distribution. For a given uncertainty norm bound, our objective is to compute the probability for no uncertainty to exist that may satisfy the prescribed bound and match the input-output measurements. While the exact computation of this probability may pose a formidable task, we derive its upper and lower bounds.

Some new thoughts and findings on Bode integrals

Abstract: This paper establishes relationships between Bode type sensitivity and complementary sensitivity integral relations and optimal tracking and regulation performance, where the latter are defined in quadratic measures. These relationships link together frequency and time domain performance constraints, and further lead to new insight into these two independent areas of research.

Robust Stability Conditions of Quasipolynomials by Frequency Sweeping

Abstract: In this chapter we study the robust stability independent of delay of some class of uncertain quasipolynomials, whose coefficients may vary in a certain prescribed range. OUr main contributions include frequency-sweeping conditions for interval, diamond and spherical quasipolynomial families. The correspoding results provide necessary and sufficient conditions, and are easy to check, requiring only the computation of two simple frequency-dependent functions. Various extensions (polytopic uncertainty, multivariate polynomials) are also presented.

On the minimal signal recovery error in multirate filterbank channel equalization

Abstract: This paper studies the constraints in filterbank design and seeks to quantify the fundamental limitations and limits inherent in this design process. The paper outlines an approach built on lifting and optimal model-matching, which attempts to quantify analytically the minimal signal recovery error in channel equalization via multirate filterbanks.