Sampled-data Feedback Control Systems Research Articles

Stabilising systems with aperiodic sample-and-hold devices: state feedback case

Motivated by the widespread use of networked and/or embedded control systems, an algorithm for stabilising sampled-data feedback control systems with uncertainly time-varying sampling intervals is proposed. The algorithm is an extension of that for stability analysis in the authors' previous study, and is based on the robustness against the variation of sampling intervals derived by the small-gain condition. The validity of the algorithm is demonstrated by numerical examples.

A Discrete-Time Approach to Stability Analysis of Systems With Aperiodic Sample-and-Hold Devices

Motivated by the widespread use of networked and embedded control systems, an algorithm for stability analysis is proposed for sampled-data feedback control systems with uncertainly time-varying sampling intervals. The algorithm is based on the robustness of related discrete-time systems against perturbation caused by the variation of sampling intervals. The validity of the algorithm is demonstrated by numerical examples.

Stability analysis of systems with aperiodic sample-and-hold devices

Motivated by the widespread use of networked and embedded control systems, improved stability conditions are derived for sampled-data feedback control systems with uncertainly time-varying sampling intervals. The results are derived by exploiting the passivity-type property of the operator arising in the input-delay approach to the system in addition to the gain of the operator, and are hence less conservative than existing ones.

Stability Analysis for a Class of Networked/Embedded Control Systems: Output Feedback Case

Motivated by the widespread use of networked and embedded control systems, an algorithm for stability analysis is proposed for sampled-data feedback control systems with uncertainly time-varying sampling intervals. The output feedback case with a dynamic compensator is considered. The algorithm is based on the robustness of related discrete-time systems against perturbation caused by the variation of sampling intervals. The validity of the algorithm is demonstrated by numerical examples.

Stability analysis of systems with aperiodic sample-and-hold devices

Motivated by recent widespread use of networked and embedded control systems, improved stability conditions are derived for sampled-data feedback control systems with uncertainly time-varying sampling intervals. The results are derived by exploiting the passivity-type property of the operator arising in the input-delay approach to the system in addition to the gain of the operator, and hence less conservative than existing ones.

On the Module of Almost Periodic Output for Sampled-Data Feedback Control Systems

The present paper is concerned with the module containment of almost periodic output for sampled-data feedback control system. Some known (periodic, quasi-periodic) results would be expanded. A special case of sampled-data feedback control systems is detailed.

ADAPTIVE CONTROL REDESIGN FOR NONLINEAR SAMPLED-DATA SYSTEMS

Semi-global practical stabilization of a general class of nonlinear sampled-data feedback control systems with unknown parameter is addressed. Due to the appearance of powers series of the unknown parameter in the analytic development of the exact discretized systems, an overparameterization is realized for the adaptive law. Then, sufficient conditions for the design of a high order controller are given, based on the Lyapunov analysis, that guarantees the desired stability properties.

On the stabilization of sampled-data non-linear systems by using backstepping on the higher order approximate models

In this paper, we study the stabilization of non-linear sampled-data feedback control systems. Our controller design is based on a backstepping procedure applied on the higher order approximations of the exact discretized associated systems.

Stability Theory of Hybrid Dynamical Systems With Time Delay

By defining the bounded time lag space and other related concepts, this note formulates the notion of hybrid dynamical systems with time delay, which provides a unified framework for describing a large class of systems and is suitable for qualitative analysis. It also investigates stability properties of invariant sets by the method of Lyapunov functions and the Razumihin techniques. Criteria on uniform stability and uniform asymptotic stability are established for hybrid dynamical systems with time delay. Those criteria are then applied to conduct stability analysis for impulsive delay differential systems and nonlinear sampled-data feedback control systems with time delay.

Uniform asymptotic stability of hybrid dynamical systems with delay

We formulate a model for hybrid dynamical systems with delay, which covers a large class of delay systems. Under several mild assumptions, we establish sufficient conditions for uniform asymptotic stability of hybrid dynamical systems with delay via a Lyapunov-Razumikhin technique. To demonstrate the developed theory, we conduct stability analyses for delay sampled-data feedback control systems including a nonlinear continuous-time plant and a linear discrete-time controller.

Qualitative behavior of output for sampled-data feedback control systems

The present paper is concerned with the qualitative behavior of output for sampled-data feedback control systems. Some sufficient conditions are established for the existence of almost periodic output, quasi-periodic output, periodic output, respectively. A special case sampled-data feedback control systems is detailed.

Nonrobustness of closed-loop stability for infinite-dimensional systems under sample and hold

It is a well-known principle, for finite-dimensional systems, that applying sampled-and-hold in the feedback loop around a stabilizing state feedback (or dynamic) controller results in a stable sampled-data feedback control system if the sampling period is small enough. The principle extends to infinite-dimensional systems with compact state feedback if either the input operator is bounded or the given state-space system is analytic. In this paper, we give an example for which this principle fails but which nevertheless satisfies certain necessary conditions arising in sampled-data control of infinite-dimensional systems.

Relating H/sub 2/ and H/sub ∞/-norm bounds for sampled-data systems

We relate the H/sub /spl infin// and H/sub 2/ norms for multi-input/multi-output sampled-data feedback control systems, where a continuous-time plant is controlled by a digital compensator with hold and sampler. Upper bounds on both H/sub 2/ and H/sub /spl infin// norms are obtained based on fundamental relations derived by two different approaches, namely the hybrid state-space approach and the fast sampling and lifting approach.

State covariance assignment for sampled-data feedback control systems

This paper proposes a new performance criterion of ‘covariance’ for sampled-data systems. A covariance of sampled-data systems is defined by taking account of inter-sample behaviour. An SCA (state covariance assignment) problem for sampled-data feedback control systems is also discussed, which is the counterpart of that for purely continuous or discrete-time feedback control systems. The SCA problem for sampled-data systems will be solved as a discrete-time SCA problem, where the discretization preserves the state covariance and is in two steps. In the first step, a certain sample time performance is required to ensure the inter-sample performance, and the output signal results to be discretized. The second step is to discretize the input signal.

Robust design of sampled-data systems with application to an electro-hydraulic position controller

Attention is drawn to the importance of the sampling frequency as a design parameter of sampled-data feedback control systems and consideration is given to its implication to the ability of the systems to withstand gross variations of the plant without unacceptable deviation from the desired performance. It is seen that the robustness of a system is intimately related to the sampling frequency as a consequence of the limitations which it imposes on the achievable loop bandwidth. Conversely, for any specified degree of robustness, the minimum frequency of sampling is well defined. However, for plants with high-frequency dynamics such as the electro-hydraulic servo discussed within the paper, time constraints imposed by a dedicated microprocessor add to the restrictions of the sampling process in such a way that it may not be possible to guarantee the existence of a discrete compensator to satisfy the given specifications.

A relation between overshoot and sampling period in sampled data feedback control systems

This correspondence shows that the overshoot of response of a sampled data feedback control system sometimes tends to infinity as the sampling period tends to zero provided that the assigned poles are constant. This suggests that an optimal sampling period exists in designing, deadbeat controllers.

Multirate digital filters

This paper provides a review of recent developments in multirate digital filters and attempts to fill a long existing gap between multirate digital filters and multirate sampled-data feedback control systems.

BIBO stability of nonlinear sampled-data multivariable feedback control systems

The definition of a state vector which takes into account the error functions of a nonlinear discrete multivariable plant allows one to obtain an estimate of the forced motions by utilising a characteristic property of the autonomous system. The result generalises that of Iwens and Bergen* obtained for monovariable plants via the discrete analogue of Popov's global-stability criterion.

On the Optimal Sampled Data Control of Strings of Vehicles

This paper deals with the control of the positions and velocities of high-speed vehicles in a single guideway. It is assumed that each and every vehicle measures its position and velocity every T seconds. The appropriate accelerations or decelerations to be applied to each vehicle are constrained to be constant during the sampling interval. Through the use of a control cost functional, which penalizes the system for any deviations from the desired headway and velocity, the required control accelerations and decelerations are obtained by deriving the system equations in discrete-time and, through the use of available results in the theory of discrete optimal control, the optimal linear time-invariant sampled-data feedback control system is determined. The general results are presented and are used to study the effect of changing the sampling time T upon the control-system performance. Since, in general, the cost of the communication system (in terms of required channel capacity, band-width, etc.) decreases with increasing values of the sampling time, the system designer has the capability of conducting trade-off studies involving the deterioration of the control system performance vs. the decrease in the cost of communication as the sampling time is increased.

Quadratic programming in the statistical design of sampled-data control systems

Quadratic programming is applied to the statistical design of sampled-data feedback control systems with finite impulse response time. Given a fixed plant, quadratic programming is used to determine the compensator which minimizes the mean-square sampled error subject to a set of constraints. The system inputs are described in terms of sampled values from autocorrelation functions. A variety of constraints can be employed, including constraints which characterize the closed-loop response of the system to deterministic inputs.