Daehyun Ji

H∞ synchronization of time-delayed chaotic systems

Abstract This paper considers H ∞ synchronization of a class of time-delayed chaotic systems with external disturbance. Based on Lyapunov theory and linear matrix inequality (LMI) formulation, the dynamic feedback controller is established to not only guarantee synchronization between derive and response systems, but also reduce the effect of external disturbance to an H ∞ norm constraint. Then, a criterion for existence of the controller is given in terms of LMIs. Finally, a numerical simulation is presented to show the effectiveness of the proposed chaos synchronization scheme.

Robust memory state feedback model predictive control for discrete-time uncertain state delayed systems

In this paper, we propose a memory state feedback model predictive control (MPC) law for a discrete-time uncertain state delayed system with input constraints. The model uncertainty is assumed to be polytopic, and the delay is assumed to be unknown, but with a known upper bound. We derive a sufficient condition for cost monotonicity in terms of LMI, which can be easily solved by an efficient convex optimization algorithm. A delayed state dependent quadratic function with an estimated delay index is considered for incorporating MPC problem formulation. The MPC problem is formulated to minimize the upper bound of infinite horizon cost that satisfies the sufficient conditions. Therefore, a less conservative sufficient conditions in terms of linear matrix inequality (LMI) can be derived to design a more robust MPC algorithm. A numerical example is included to illustrate the effectiveness of the proposed method.

Development of bending gap measurement and position control technique for unmanned slab crane

The development of unmanned crane is an important issue of factory automation (FA) in steel industry. In slab yard, various kind of slabs(different ingredients, temperature, length, width and thickness and so on) are piled together. When hot slabs were piled and get cold gradually, deformation such as bending of slabs is occurred due to the thermal expansion and contraction. It may make slab to be bend and make gaps between slabs. Basically, gripping position control of unmanned slab crane is entirely depends on thickness information of target slabs in data base. The bending of piled slabs makes a difference of total task height between database and real one. It can cause unstable slab gripping and can cause a falling of slabs during the transportation. To resolve this problem, we developed a new gap measuring system which is equipped on the tip of crane and control system to make the crane grip stably. In this paper, a new gap measuring and grip position control system for slab crane and experimental results are described.

Non-linear observer-based trajectory tracking control for wheeled mobile robot

In this paper, non-linear observer-based trajectory tracking control for a wheeled mobile robot is proposed. The non-linear observer is designed for not only an unmeasurable orientation error but current position error. This full-order observer shows robustness to measurement noise. Besides, a controller which exponentially stabilizes the tracking error is used. The non-linear observer with the controller is asymptotically stable by means of persistently exciting (PE) condition and cascaded system theory. A proof of stability and simulation results are given.

Robust model predictive control for uncertain state delayed system using polytope dependent Lyapunov function

In this paper, we propose a method of computing a improved model predictive control (MPC) law for uncertain state delayed system with unknown bounded delay term and input constraints. The proposed method improves feasibility characteristics and system tracking performance by deriving a sufficient condition for the cost monotonicity using polytope dependent Lyapunov function corresponding to a different vertex. The control problem is formulated as a minimization of the upper bound of infinite horizon cost function satisfying the sufficient conditions. The polytope dependent Lyapunov function yield less conservative sufficient condition in terms of linear matrix inequalities (LMIs) so that it allows to design a more robust MPC. A numerical example is included to illustrate the effectiveness of the proposed method.

A new fuzzy stabilizer with tuning parameters for nonlinear system

In this paper, we consider a new fuzzy stabilizer which has tuning parameter so as to be applicable easily in real nonlinear plants. We adopted Inverse LQ(ILQ) regulator design method in which the state feedback control law is optimal for some unknown weights, thereby simplifying the design procedures. A design procedure is developed to extend the applications of ILQ regulator design method to nonlinear plants described by Takagi-Sugeno (TS) fuzzy model. Since ILQ control laws are optimal for each linear subsystems of TS fuzzy model, the weighted sum of general fuzzy stabilizer control law and ILQ control shows better performance than selecting one alternative. An numerical example is provided to illustrate the procedures of the proposed method.

Dynamic output feedback H ∞ receding horizon controller design for uncertain discrete-time system with parameter dependent Lyapunov function

In this paper, we present a dynamic output feedback Hinfin receding horizon controller for uncertain systems with both norm bound uncertainty and disturbance using new parameter dependent Lyapunov function. This Lyapunov function is proposed to get a less conservative condition and guarantees both closed loop stability and the Hinfinnorm bound. The controller is obtained numerically from the output feedback Hinfin optimization problem, which is hardly solved analytically. The results are illustrated with numerical example

Dynamic output feedback H ∞ receding horizon controller design for uncertain discrete-time system with parameter dependent Lyapunov function

In this paper, we present a dynamic output feedback Hinfin receding horizon controller for uncertain systems with both norm bound uncertainty and disturbance using new parameter dependent Lyapunov function. This Lyapunov function is proposed to get a less conservative condition and guarantees both closed loop stability and the Hinfinnorm bound. The controller is obtained numerically from the output feedback Hinfin optimization problem, which is hardly solved analytically. The results are illustrated with numerical example