백승민 교수

This paper proposes a new adaptive law for a sliding mode control (SMC) scheme to achieve the effective switching gain tuning near the sliding surface. The proposed adaptive law makes the switching gains rapidly and effectively decrease near the sliding surface to provide the well-functioning adaptation while avoiding the sign changes caused by excessive adaptation. Such an adaptation mechanism contributes to chattering reduction and fast adaptation of the switching gains without temporary large

In this article, we propose an innovative model-free control (MFC) algorithm using an adaptive model uncertainty estimator (AMUE) that provides stable torque input while allowing more precise control, even in the presence of instantaneous disturbances, such as friction, payload, or trajectory changes. Unlike traditional time-delay estimation (TDE)-based controllers that directly use one-sample delayed signals to estimate unmodeled dynamics and uncertainties, the proposed algorithm achieves bette

With only the classical PID controller applied to control of a DC motor, a good (target) performance characteristic of the controller can be obtained, if all the model parameters of DC motor and operating conditions such as external load torque, disturbance, etc, are exactly known. However, in case when some of system parameters or operating conditions are uncertain or unknown, the fixed PID controller does not guarantee the good performance which is assumed with precisely known system parameter

This article proposes a communication-efficient event-triggered time-delay control (ET-TDC) scheme, which is more intelligent, consumes fewer network resources, and is more suitable for practical applications, such as network control systems over bandwidth-limited communication channels. The proposed controller ensures a fast convergence rate and high tracking performance because it is based on TDCs that are well known for achieving high tracking performance. To maintain these properties, the pr

MAT usually affects infants and has a favorable prognosis, particularly in the idiopathic infant group. However, in the presence of other comorbidities, MAT may have a variable clinical course.

We demonstrate properties of magnetophotonic crystals (MPCs) with quasi-two-dimensional structure. Crystals were bismuth-substituted yttrium iron garnet/silicon dioxide (Bi:YIG/SiO2) multilayers sputtered on top of one-dimensional structured substrates. Parameters of these MPCs were such that two spectrally neighboring stop bands overlapped in their spectra. For MPCs in this multiple Bragg diffraction regime, we observed a strong dispersion of their magneto-optical responses—an enhancement of th

Although robot manipulators are widely used in advanced industrial applications, their dynamics has very high complexity and uncertainties, making exact mathematical modeling difficult and preventing high-precision tracking control. Herein, we propose a practical high-performance model-free controller for robot manipulators that attenuates the undesirable side effects of a time-delayed state-based estimation (TDE) technique in terms of the receding-horizon <inline-formula xmlns:mml="http://www.w

Electrical design and withstand test of mini-model coils for high temperature superconducting fault current limiter (HTSFCL) have been studied. Electrical insulating factors of the HTS coil for HTSFCL are turn-to-turn and layer-to-layer. The electrical insulation of turn-to-turn depends on surface length, and the electrical insulation of layer-to-layer depends on surface length and breakdown strength of LN/sub 2/. Therefore, two basic characteristics of breakdown and flashover voltage were exper

Bismuth-substituted yttrium iron garnet (Bi:YIG)-based two-dimensional (2D) magnetophotonic structures were fabricated on top of opal thin films. Autocloning approach was used to transpose 2D hexagonal symmetry of the opal (111) plane into sputtered Bi:YIG. Resultant 2D patterned Bi:YIG films had two realizations. As-sputtered films had a hemispherical profile of structural elements. These films were additionally etched to obtain films with a cone profile of scatterers. Optical and magneto-optic

This study proposes an innovative reinforcement learning-based time-delay control (RL-TDC) scheme to provide more intelligent, timely, and aggressive control efforts than the existing simple-structured adaptive time-delay controls (ATDCs) that are well-known for achieving good tracking performances in practical applications. The proposed control scheme adopts a state-of-the-art RL algorithm called soft actor critic (SAC) with which the inertia gain matrix of the time-delay control is adjusted to

This paper presents a situation-based task selection mechanism which enables a life supporting robot system to perform tasks-based on the user's situation. Stimulated by interactions between robot and user, this mechanism constructs and updates the association between the user's situation and tasks so that the robot could adapt to user's behaviors related to the robot's tasks effectively. For the user adaptation, radial basis function networks (RBFN) and associative learning algorithms are used.

Bismuth-substituted yttrium iron garnet (Bi:YIG)-based magnetophotonic crystals (MPCs) with 2D structure were fabricated using autocloning of various patterns. We studied structural properties of these MPCs and evaluated their magneto-optical responses. Enhanced Faraday rotation of the same sign as that for conventional Bi:YIG films and of the opposite sign was observed for 2D patterned Bi:YIG films fabricated on top of opal films.