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Donghoon Shin,Youngwoo Lee,Wonhee Kim,Chung Choo Chung 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10
In this paper, we present an observer based nonlinear controller using barrier Lyapunov function (BLF) for position tracking of Sawyer motor under yaw constraint. The dynamics of Sawyer motor is modified to apply BLF-based backstepping control design. To relax the matching condition, torque and force modulations are proposed. The modulations enable decoupling forces and torque of the Sawyer motor, and facilitate implementing the design of backstepping controller with the BLF. In addition, we propose a state augmented nonlinear observer to estimate the velocities, yaw rate, load forces and load torque. We show the closed-loop stability with a composite Lyapunov function. Simulation results validate the effectiveness of the proposed method.
Observer Based Nonlinear Tension Control for Multi MotorWireWinding System
Donghoon Shin,Wonhee Kim,Youngwoo Lee,Daehee Won,Chung Choo Chung 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
In this paper, we present a tension control method for multi motor wire winding systems (MWSs). The objectives of MWS are tracking both the tension and velocity of wire. A velocity controller for rewinding motor is designed. A tension controller, whose inner loop is the velocity controller for unwinding motor, is developed. To filter out the measurement noises of velocities and estimate the load torque of motors, an augmented observer is proposed. The proposed method ensures good performance in the presence of the measurement noises of velocities noise and load torque. Simulation results validate the effectiveness of proposed method.
TVWS assisted performance anomaly mitigation exploiting spectrum heterogeneity
Shin, Kyubo,Kim, Hyoil,Chun, Se Young,Shin, Donghoon Elsevier 2018 COMPUTER NETWORKS - Vol.141 No.-
<P><B>Abstract</B></P> <P>Super Wi-Fi is a Wi-Fi-like service utilizing TV white spaces (TVWS), which has been revealed to provide higher data rates in the outskirts of Wi-Fi’s coverage, thanks to the spectrum heterogeneity between Wi-Fi bands and TVWS. Motivated by this, this paper proposes co-locating a Super Wi-Fi access point (AP) with a Wi-Fi AP aiming to mitigate the performance anomaly of the WLAN by relocating low-rate Wi-Fi stations (STAs) to Super Wi-Fi in the outskirts of Wi-Fi’s coverage. Then, the proposed strategy can enhance average per-STA throughput of both Wi-Fi STAs and relocated Super Wi-Fi STAs while also improving the data rate of Super Wi-Fi STAs, than they would achieve with the legacy Wi-Fi. To quantify such performance improvement, we model the system as a series of two-dimensional Markov chains and provide an in-depth analysis of steady-state probabilities and per-STA throughput. Numerical analysis has shown that Super Wi-Fi co-location improves <I>not only</I> average per-STA throughput <I>but also</I> spectral efficiency, compared to the legacy Wi-Fi with 20 or 20+20 MHz bandwidth for the single BSS scenario. In addition, average per-STA throughput and spectral efficiency are also enhanced in the OBSS scenario both in rural and urban environments. Hence, the co-location strategy is proven to be quite effective in enhancing WLAN’s performance.</P>
Human-Centered Risk Assessment of an Automated Vehicle Using Vehicular Wireless Communication
Shin, Donghoon,Kim, Beomjun,Yi, Kyongsu,Carvalho, Ashwin,Borrelli, Francesco IEEE 2019 IEEE transactions on intelligent transportation sy Vol.20 No.2
<P>This paper presents a human-centered risk assessment algorithm using vehicular communication for application to an automated driving vehicle. Vehicle-to-vehicle (V2V) wireless communication has been implemented and fused with a radar sensor to obtain the prediction of the remote vehicle’s motion. Based on the predicted behavior of remote vehicles, a collision risk and a human reaction time are determined for a human-centered active safety control intervention moment. The human-centered risk assessment algorithm has been incorporated into a collision avoidance algorithm to monitor threat vehicles ahead and to find the best intervention point. Effects of the vehicular communication on a perception and a control performance are investigated. The performance of the proposed algorithm has been investigated via computer simulations and vehicle tests. It has been shown from both simulations and vehicle tests that the proposed human-centered risk assessment algorithm with V2V communication decides a proper active safety intervention moment by reducing the chances of over/underestimate of a conventional radar-only system.</P>
An efficient algorithm for frequency estimation from cosine-sum windowed DFT coefficients
Shin, Donghoon,Kwak, Chulhyun,Kim, Gwangtae Elsevier 2020 Signal processing Vol.166 No.-
<P><B>Abstract</B></P> <P>This paper presents an algorithm for estimating frequency of a complex sinusoid from three DFT coefficients. In particular, we consider the case where the signal is multiplied by a generic cosine-sum window for interference suppression. The algorithm is an interpolator that uses the peak sample in the DFT of the data and its two neighbors. The interpolator is based on a numerically efficient procedure which guarantees convergence to a solution. Performance of the proposed interpolator is shown to be nearly optimum and comparable to the best interpolator in the literature, while the computational burden required for the proposed algorithm is much lower than the generic numerical methods available. Degradation of performance due to interference is also investigated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A numerically efficient method for frequency estimation by Interpolation on DFT coefficients. </LI> <LI> The use of generic cosine-sum windows for interference suppression. </LI> <LI> Performance that nearly achieves the Cramer–Rao bounds. </LI> </UL> </P>
Nonlinear Position Control for Permanent Magnet Stepper Motor Using Only Position Feedback
Donghoon Shin,Wonhee Kim,Youngwoo Lee,Chung Choo Chung 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10
In this paper, we present a nonlinear controller for position tracking of permanent magnet stepper motors (PMSMs) using only position feedback. A virtual velocity is designed to improve the position tracking performance and virtual currents are proposed in order to guarantee the virtual velocity. An integrator of position tracking error is added into the virtual currents for reducing the steady-state error in position tracking caused by the load torque. The proposed controller guarantees that the position, velocity and currents tracking errors globally exponentially converge to zero. Furthermore, the proposed controller is robust against the load torque. By using passive properties of PMSMs, the requirements of the velocity and current measurements were removed. Simulation results validate the effectiveness of the proposed controller.