Kang-Bak Park

The ultimate bounds of equivalent control based sliding-mode control systems with short sampling time

Almost all of control systems proposed so far have been designed in the continuous-time domain. Actual systems, however, have been implemented in the discrete-time domain since microprocessors have been used for the controller, that is, the overall system turned to be a sampled-data system. In this case, the ultimate error and/or steady state error cannot converge to zero in the actual system even though the proposed control algorithm showed the asymptotic stability in the continuous-time domain. In this paper, therefore, the ultimate error bound of a second-order sampled data system with the short sampling time has been investigated. The ultimate error is shown to be related in the sampling period.

Stability of equivalent control based discrete sliding mode controller

In this paper, the stability condition of a discretized sliding mode control system is studied. For the conventional system, the stability of the closed-loop system is dependent on the sampling time, i.e., it turns to be unstable over a sampling period, and is stable under the sampling period. For the given system, however, it is shown that the interval of stable and unstable sampling periods appears alternately. It is also shown that the stability of the overall system can be predicted by checking up the magnitude of one parameter of the discretized system.

Design of Extended Terminal Sliding Mode Control Systems

The terminal sliding mode control schemes have been studied a lot since they can guarantee that the state error gets to zero in a finite time. However, the conventional terminal sliding surfaces have been designed using power function whose exponent is a rational number between 0 and 1, and whose numerator and denominator should be odd integers. It is clearly restrictive. Thus, in this paper, we propose a novel terminal sliding surface using power function whose exponent can be a real number between 0 and 1.

Sliding mode controller with nonlinear sliding surface for a second order system with input saturation

In this paper, a sliding mode controller for a second order system with input saturation is proposed. The proposed method uses a nonlinear sliding surface to ensure that the control signal generated by the controller does not exceed the bounds of a system input.

Estimation of burn-through point in the sinter process

In sintering process, the operator determined the sinter pallets speed based on the location of BTP. Therefore, it is important to estimate the BTP so that the reliability is high. Quadratic curve was inferred by the curve fitting about wind box with the highest temperature and the sides of the wind box in previous studies. This allows, BTP was estimated. However, this is a disadvantage the correlation coefficient is small where except for the three points. In this paper, wind box is reflected from 17 up to 25, and wind box with the highest temperature and the sides of the wind box are added in range of curve fitting. This was fitted the cubic and fifth-order curve. BTP were estimated in this condition is similar to the actual temperature curve.

Stability Criterion for Sampled-Data System with Sliding Mode Controller

Although most of control methods have been studied in the continuous-time domain, the actual control systems have been implemented using MCU (Micro Control Unit) and/or microprocessors so that the overall systems turn to be sampled-data systems. In this case, the stability criterion of the closed-loop system is not easy to derive. In this paper, a simple stability criterion for the sampled-data system with sliding mode controller is derived.

The Ultimate Bound of Discrete Sliding Mode Control System with Short Sampling Period for DC Motor System

Almost all of control schemes proposed so far have been designed in the continuous-time domain theoretically. Actual systems, however, have been implemented in the discrete-time domain since Micro Control Unit(MCU) and/or microprocessors have been used for the controllers. Thus, the overall system turned to be a sampled-data system, and generally speaking, the ultimate error cannot converge to zero in the actual system even though the proposed control algorithm showed the asymptotic stability in the continuous-time domain. In this paper, therefore, the ultimate error bound of a sampled data system with a short sampling period has been investigated. The ultimate error is shown to be related in the sampling period.

Discretization behaviors of equivalent control based sliding-mode control systems with external disturbances

In this paper, we study discretization behaviors of the equivalent control based sliding-mode control (SMC) systems. According to the variation of system parameters, the inherent dynamical behavior of the trajectories within some specified boundaries are discussed. Also upper bounds for the system steady states using symbolic dynamics approach are established. Some dynamical properties of the discretized second-order systems under the existence of uncertainties and disturbances are first explored. This paper include upper bounds for this systems steady states and steady state behaviors, which has not been addressed before. Simulations are presented to verify the theoretical results.

The ultimate bound of a sampled-data sliding mode control system for second-order systems with time-varying disturbance

Although system is generated in continuous time domain, actual system is in discrete time domain because experimental devices are digital. In this reason, system is not asymptotically stable. It causes that ultimate error cannot converge to zero in finite time. So ultimate error bound is needed to inspect overall system. In previous researches, disturbance that is used to derivate ultimate error bound was constant. In this paper, disturbance is extended into time-varying one. In very short sampling time, ultimate error bound with constant disturbance are related with system that affected by time-varying disturbance.

Extended Nonsingular Terminal Sliding Surface for Second-Order Nonlinear Systems

An extended nonsingular terminal sliding surface is proposed for second-order nonlinear systems. It is shown that the proposed surface is a superset of a conventional nonsingular terminal sliding surface which guarantees that the system state gets to zero in finite time. The conventional nonsingular sliding surfaces have been designed using a power function whose exponent is a rational number with positive odd numerator and denominator. The proposed nonsingular terminal sliding surface overcomes the restriction on the exponent of a power function; that is, the exponent can be a positive real number. Simulation results are provided to show the validity of the main result.