Junmin Park

An improved stability criteria for neutral-type Lur’e systems with time-varying delays

Abstract This paper improves stability criteria for neutral-type Lur’e systems with time-varying delays, where the nonlinearity satisfies sector and slope restrictions. A proposed Lyapunov–Krasovskii functional consisting of a quadratic term and integral terms for the time-varying delays and the nonlinearities, has four different characteristics. First, the quadratic term utilizes not only the current and delayed states but also the nonlinear vectors. Second, the integral terms for nonlinearities fully exploit the characteristics of sector and slope restrictions. Third, the integral terms for nonlinearities also exploit the characteristic of incremental restriction induced from the slope restriction. Fourth, this paper utilizes a vector related to the time derivative of the neutral delayed state to handle the neutral delay. Based on the proposed Lyapunov–Krasovskii functional, the improved stability criteria are derived in terms of linear matrix inequalities. Numerical examples show that the proposed criteria present less conservative results than the previous criteria.

Adaptive sliding mode control for stabilization of stochastic chaotic systems with multi-constraints

This paper proposes an adaptive sliding mode control scheme for stabilization of two different stochastic chaotic systems with multi-constraints such as model uncertainties, disturbances, input nonlinearities and stochastic unknown parameters which are generated by the Wiener process. Using an adaptive control and a fuzzy logic systems, model uncertainties, disturbances and stochastic unknown parameters are estimated and applying only a low bound of input nonlinearity, input nonlinearity is handled. Based on Lyapunov stability theory, the proposed scheme can stabilize the stochastic chaotic systems and guarantee global stability of them. The simulation results show the effectiveness of the proposed scheme.

Modified function projective synchronization for two different chaotic systems using adaptive fuzzy nonsingular terminal sliding mode control

This paper proposes an adaptive fuzzy nonsingular terminal sliding mode control (AFNTSMC) scheme for modified function projective synchronization (MFPS) of two different chaotic systems with unknown functions. The proposed scheme combines adaptive fuzzy logic control (AFLC) with fuzzy nonsingular terminal sliding mode control (FNTSMC). The AFLC can estimate the unknown functions. The FNTSMC can reduce chattering phenomenon and convergence time of error states to finite time. The proposed scheme synchronizes these chaotic systems in finite time. The simulation results show the effectiveness of the proposed scheme.

H∞ sampled-state feedback control for synchronization of chaotic Lur’e systems with time delays

Abstract This paper investigates H ∞ sampled-state feedback control for synchronization of chaotic Lur’e systems with time delays under the aperiodic samplings. First, this paper proposes an improved stability criterion for sampled-state feedback control to synchronize the chaotic Lur’e systems with time delays under aperiodic samplings by constructing a novel Lyapunov–Krasovskii functional. Compared with the literature, the novel Lyapunov–Krasovskii functional utilizes the fragmented state and its state-space model which is defined between the last sampling instant and the present time. Second, this paper introduces an H ∞ performance index for H ∞ sampled-state feedback control of synchronization error systems considering the state-space model of the fragmented state. Based on the proposed Lyapunov–Krasovskii functional and the H ∞ performance index, the stability criterion and the H ∞ control criterion are derived in terms of linear matrix inequalities, respectively. A numerical example shows the effectiveness of the proposed criterion.

Vibration control of a strip in a continuous galvanizing line using self-tuning neuro-PID controller

This paper proposes a vibration control scheme of a strip in a continuous galvanizing line using neuro-PID controller which consists of two neural networks and conventional PID controller. One NNs estimates the strip model using input-output data of the strip and other NNs updates the gains of conventional PID controller using the estimated strip model and errors between the desired and actual outputs. The proposed scheme gives the adaptation ability for different strips and operating conditions. To show the effectiveness of the proposed scheme, the FEM model of a strip derived by ANSYS is used for simulation. The simulation result shows that the proposed scheme provides the small estimation error, the reduced strip oscillation and efficient gain tunning.

State dependent disturbance compensation method for motor control system with unknown input time delay

This paper proposes a periodic adaptive state dependent disturbance observer (PASDDOB) for motor control with the unknown input time delay, known output time delay and unknown phase delay from Q-filter to compensate the state dependent disturbance (SDD) that changes slowly by time. The PASDDOB has a structure that combines the state dependent disturbance observer (SDDOB) with the periodic adaptive learning compensation (PALC). The SDDOB compensates the known output delay and the unknown phase delay from Q-filter. The PALC compensates the unknown input time delay and the time-varying SDD. Therefore, the PASDDOB can compensate the SDD. The effectiveness of the proposed state dependent disturbance compensation method is demonstrated using MATLAB simulation results.

Decentralized guaranteed cost control for uncertain large-scale singular systems via proportional-plus-derivative state feedback

In this paper, decentralized guaranteed cost control for uncertain large-scale singular systems are studied. The parametric uncertainty which is assumed be norm-bounded exists not only in system matrices, but also in a derivative matrix. For the stabilization of the given system, guaranteed cost proportionalplus-derivative state feedback is suggested. The linear matrix inequality (LMI) condition which guarantees quadratic performance index is given. Numerical examples are shown to validate the proposed control.