Hee-Seob Ryu

Compensation of networked control systems using LMI-based delay-dependent optimization method

Transmission delays in networked control systems are inevitable and can degrade the system performance or stability. The paper proposes a compensation method for networked control systems with network induced delay using a LMI-based delay-dependent optimization method. The delay-dependent optimization method has been adapted to provide an upper bound of the delay such that the system is asymptotically stable. Some simulations applied to numerical examples with networked control show that the proposed method works well.

Robust H/sub /spl infin// FIR filter for discrete-time uncertain systems

A robust H/sub /spl infin// filter with FIR (finite impulse response) structure is proposed for linear discrete time-varying uncertain systems represented by the state-space model having parameter uncertainty. Firstly, when there is no parameter uncertainty in the system, the discrete-time H/sub /spl infin// FIR filter is derived by using the equivalence relationship between the FIR filter and the recursive filter, which corresponds to the standard H/sub /spl infin// filter. Secondly, when the system has the parameter uncertainty, the robust H/sub /spl infin// FIR filter is proposed for the discrete-time linear uncertain system. It is also derived from the equivalence relationship between the robust H/sub /spl infin// FIR filter and the robust H/sub /spl infin// filter proposed by de Souza and Xie (1994) and Xie et al. (1991) for discrete-time systems. Estimation performance of the discrete-time H/sub /spl infin// FIR filters proposed is compared with two other techniques, Kalman filter and the robust H/sub /spl infin// filter, via some simulations to exemplify the performance superiority of the proposed method over other techniques.

Robust H∞ Fir Filter for Uncertain Systems

Abstract This paper deals with the issue of the robust H ∞ FIR (Fmite Impulse Response) filtering problem for linear systems with parameter uncertainty in the state-space model. Firstly, the H ∞ FIR filter is presented for the system without the uncertainty, which corresponds to the H ∞ filter proposed by Nagpal and Khargonekar (1991). The impulse response of the H ∞ FIR filter is calculated by the equivalence relationship between the FIR filter and the recursive filter (Kwon et al., 1990; 1994). Secondly, the robust H ∞ FIR is proposed for the linear uncertain system with the parameter uncertainty. It is also derived from the relationship between the robust Hqq FIR filter and the robust Hoo filter proposed by Xie and de Souza (1991) and Fu et al. (1992). Estimation performances of the H ∞ FIR filters proposed are compared with two other techniques by Kalman filter and the robust H ∞ filter (Shaked and Theodor, 1992; Fu et at., 1992) via some simulations to exemplify the superiority of the proposed method over other techniques.

Fundamental limitations imposed by RHP poles and zeros in SISO systems

Establishes limitations on the impulse response of an LTI system based on the open-loop poles and zeros located in the convergence region of the closed-loop transfer function. Using the definition of Laplace transform, it is shown that time-domain integral constraints have to be satisfied by the impulse response of the SISO stable system and that the maximum value of impulse response has some lower bounds according to the achievable settling time of the system. Also, it shows the reason why it is very difficult to control the system with open-loop RHP (right half plane) poles or zeros using the unity-feedback scheme in the view of small impulse response. These results can be used to determine a priori whether desired design specifications axe achievable or not.

Robust H/sub /spl infin// FIR filtering for nonlinear time-varying systems

This paper investigates the robust H/sub /spl infin// filter with FIR (finite impulse response) structure for nonlinear discrete time-varying uncertain systems represented by the state-space model having parameter uncertainty.

Robust H/sub /spl infin// FIR filtering with sampled-data measurements

The problem of robust H/sub /spl infin// filter with FIR (finite impulse response) structure for linear continuous time-varying systems with sampled-data measurements is to be considered. It is assumed that the system is subject to real time-varying uncertainty which is represented by the state-space model having parameter uncertainty. The sampled-data system is represented by using piecewise continuous system with finite jumps. The robust H/sub /spl infin// FIR filter is derived by using the equivalence relationship between the FIR filter and the recursive filter, that would be guarantee a prescribed H/sub /spl infin// performance in the continuous-time context, irrespective of the parameter uncertainty and unknown initial states.

Robust H/sub /spl infin// FIR filtering for uncertain time-varying nonlinear systems

Investigates the robust nonlinear H/sub /spl infin// filter with FIR (finite impulse response) structure for nonlinear discrete time-varying uncertain systems represented by the state-space model having parameter uncertainty. Firstly, the discrete-time nonlinear H/sub /spl infin// FIR filter without parameter uncertainty is derived by using the equivalence relationship between the FIR filter and the recursive filter, which corresponds to the standard nonlinear H/sub /spl infin// filter. Secondly, the robust H/sub /spl infin// FIR filter is proposed for discrete-time nonlinear uncertain systems. It is also derived from the equivalence relationship between the robust nonlinear H/sub /spl infin// FIR filter and the robust nonlinear H/sub /spl infin// filter proposed by de Souza et al. (1993).