Adaptive integral sliding mode control for nuclear research reactor with system uncertainties and input perturbation

Eom, Myunghwan,Chwa, Dongkyoung IET 2016 Electronics letters Vol.52 No.4

<P>A chattering free adaptive integral sliding mode control (AISMC) for a nuclear research reactor system in the presence of system uncertainties and input perturbation is presented. The proposed control method ensures finite time stability and also eliminates the chattering phenomenon. Also, using a deadzone technique, the upper bound of unknown system uncertainty can be estimated. The proposed AISMC can compensate for a reactivity feedback term significantly affecting the reactor system in the form of input perturbation, which is not possible in the case of integral sliding mode control (ISMC). Through simulation results, the effectiveness of the proposed controller is compared with the ISMC method for a nuclear research reactor system, and the effectiveness of the proposed control method is confirmed.</P>

Robust Swing-Up and Balancing Control Using a Nonlinear Disturbance Observer for the Pendubot System With Dynamic Friction

Myunghwan Eom,Dongkyoung Chwa IEEE 2015 IEEE TRANSACTIONS ON ROBOTICS Vol.31 No.2

<P>This paper proposes the robust swing-up and balancing control method using a nonlinear disturbance observer for the pendubot system in the presence of dynamic friction. First, the uncertainties in the pendubot system are verified through the experiment to take the form of a continuous and differentiable friction model. Then, the uncertainties present in both actuated and unactuated dynamics are shown to have the coupled form between them through the analysis, such that they can be compensated by estimating only one of them. In order to compensate for the uncertainties, the robust swing-up control is proposed. Then, the limit-cycle phenomenon, which appears around the unstable equilibrium point due to the uncertainties is compensated in the robust balancing control using the nonlinear disturbance observer, and the disturbance estimation errors are shown through the stability analysis to converge to zero. Finally, the performance and the validity of the proposed method are verified through both simulation and experimental results.</P>

Sliding Mode Disturbance Observer‑Based Robust Prescribed Performance Tracking Control for Research Reactor

Myunghwan Eom,Dongkyoung Chwa 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1

This paper presents a sliding mode disturbance observer (SMDO)-based robust prescribed performance control (RPPC) method for research reactor systems with system uncertainty. The existing reactor control methods have not considered the disturbance compensation and improvement of the transient response at the same time although both of these issues are much important in the reactor control. To achieve these control objectives, the prescribed performance function is introduced and then the SMDO-based RPPC is designed for the research reactor such that the transient tracking error remains within the desired bound even in the presence of the system uncertainty. The stability of the overall research reactor control system is analyzed and simulation results are provided to demonstrate the validity of the proposed method.

Robust Disturbance Observer-Based Feedback Linearization Control for a Research Reactor Considering a Power Change Rate Constraint

Myunghwan Eom,Dongkyoung Chwa,Baang, Dane IEEE 2015 IEEE transactions on nuclear science Vol.62 No.3

<P>This paper presents a robust disturbance observer-based feedback linearization control method using a fuzzy-based power change rate limiting method for a research reactor. The proposed controller has been designed for a nonlinear model of the reactor. Compared to the conventional control methods, the proposed scheme shows better control performance as it provides effective compensation for the steady-state error, due to a specific type of unmodeled dynamics. To cope with system uncertainties such as parameter uncertainties, unmodeled dynamics, and even external disturbance, we propose a robust disturbance observer-based feedback linearization controller. Moreover, the fuzzy-based power change rate limiting method is proposed, which is practically required for safe operation to limit the power change rate within a pre-designed safety range. In addition, a motor control input is considered and obtained by using the inverse model for the power control system. We show by numerical simulation that the proposed control law guarantees asymptotic stability as well as improved performance even in the presence of disturbance.</P>

Anti-Sway Control of the Overhead Crane System using HOSM Observer

Kwon, Dongwoo,Eom, Myunghwan,Chwa, Dongkyoung The Korean Institute of Electrical Engineers 2016 Journal of Electrical Engineering & Technology Vol.11 No.4

This paper proposes a sum of squares (SOS) method for anti-swing control of overhead crane system using HOSM (High-Order Sliding-Mode) observer. By representing the dynamic equations of overhead crane as the polynomial dynamic equations via Taylor series expansion, the control input is obtained from the converted polynomial dynamic equations by numerical tool SOSTOOL. Since the actual crane systems include disturbance such as wind and friction, we propose a method to compensate for the disturbance by estimating the disturbance using HOSM observer. Numerical simulations show the effectiveness and the applicability of the proposed method.

Disturbance-Estimation-Based Hierarchical Sliding Mode Control of Hovercraft with Wind Disturbance

Seongchan Jeong,Myunghwan Eom,Dongkyoung Chwa 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

This paper proposes disturbance-estimation-based hierarchical-sliding-mode tracking control method for hovercraft in the presence of wind disturbance. Both a disturbance estimator for wind disturbance that has strong uncertainty and hierarchical sliding mode tracking controller for hovercraft system are designed. This paper defines three sliding surfaces and derives all sliding surfaces converge to zero within finite time. Through the proposed method, the control performance is improved over the conventional method and compensation for the external disturbances can be possible.

Robust Swing Up and Balancing Control of the Acrobot Based on a Disturbance Observer

Sanghyob Lee,Myunghwan Eom,Dongkyoung Chwa 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

This paper proposes robust swing up and balancing control scheme of the acrobot system based on a disturbance observer. The partial feedback linearization and LQR control method are fast and effective way to control the nominal acrobot system. However, these control method does not guarantee the robustness. Also, the limit cycle phenomenon which appears in the acrobot system around the desired unstable equilibrium point can be assumed a sinusoidal signal. Therefore, disturbance observer for the sinusoidal disturbance is applied to develop the compensation scheme which minimizes the effect of the disturbance. The proposed control strategy was verified through the simulation results.

Anti-Sway Control of the Overhead Crane System using HOSM Observer

Dongwoo Kwon,Myunghwan Eom,Dongkyoung Chwa 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.4

This paper proposes a sum of squares (SOS) method for anti-swing control of overhead crane system using HOSM (High-Order Sliding-Mode) observer. By representing the dynamic equations of overhead crane as the polynomial dynamic equations via Taylor series expansion, the control input is obtained from the converted polynomial dynamic equations by numerical tool SOSTOOL. Since the actual crane systems include disturbance such as wind and friction, we propose a method to compensate for the disturbance by estimating the disturbance using HOSM observer. Numerical simulations show the effectiveness and the applicability of the proposed method.

Adaptive Sliding Mode Traffic Flow Control using a Deadzoned Parameter Adaptation Law for Ramp Metering and Speed Regulation

Jin, Xin,Eom, Myunghwan,Chwa, Dongkyoung The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.5

In this paper, a novel traffic flow control method based-on ramp metering and speed regulation using an adaptive sliding mode control (ASMC) method along with a deadzoned parameter adaptation law is proposed at a stochastic macroscopic level traffic environment, where the influence of the density and speed disturbances is accounted for in the traffic dynamic equations. The goal of this paper is to design a local traffic flow controller using both ramp metering and speed regulation based on ASMC, in order to achieve the desired density and speed for the maintenance of the maximum mainline throughput against disturbances in practice. The proposed method is advantageous in that it can improve the traffic flow performance compared to the traditional methods using only ramp metering, even in the presence of ramp storage limitation and disturbances. Moreover, a prior knowledge of disturbance magnitude is not required in the process of designing the controller unlike the conventional sliding mode controller. A stability analysis is presented to show that the traffic system under the proposed traffic flow control method is guaranteed to be uniformly bounded and its ultimate bound can be adjusted to be sufficiently small in terms of deadzone. The validity of the proposed method is demonstrated under different traffic situations (i.e., different initial traffic status), in the sense that the proposed control method is capable of stabilizing traffic flow better than the previously well-known Asservissement Lineaire d'Entree Autoroutiere (ALINEA) strategy and also feedback linearization control (FLC) method.

Adaptive Sliding Mode Traffic Flow Control using a Deadzoned Parameter Adaptation Law for Ramp Metering and Speed Regulation

Xin Jin,Myunghwan Eom,Dongkyoung Chwa 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.5

In this paper, a novel traffic flow control method based-on ramp metering and speed regulation using an adaptive sliding mode control (ASMC) method along with a deadzoned parameter adaptation law is proposed at a stochastic macroscopic level traffic environment, where the influence of the density and speed disturbances is accounted for in the traffic dynamic equations. The goal of this paper is to design a local traffic flow controller using both ramp metering and speed regulation based on ASMC, in order to achieve the desired density and speed for the maintenance of the maximum mainline throughput against disturbances in practice. The proposed method is advantageous in that it can improve the traffic flow performance compared to the traditional methods using only ramp metering, even in the presence of ramp storage limitation and disturbances. Moreover, a prior knowledge of disturbance magnitude is not required in the process of designing the controller unlike the conventional sliding mode controller. A stability analysis is presented to show that the traffic system under the proposed traffic flow control method is guaranteed to be uniformly bounded and its ultimate bound can be adjusted to be sufficiently small in terms of deadzone. The validity of the proposed method is demonstrated under different traffic situations (i.e., different initial traffic status), in the sense that the proposed control method is capable of stabilizing traffic flow better than the previously well-known Asservissement Lineaire d"Entree Autoroutiere (ALINEA) strategy and also feedback linearization control (FLC) method.