• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.180-188
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• 1999

${\mu}$-synthesis is applied to design a robust controller for a seeker scan loop system which has model uncertainty and is subject to a external disturbance due to abrupt missile maneuver. The issue of modelling a real-valued parametric uncertainty of a physical seeker scan loop system is discussed. The two-degree-of-frame control structure is employed to obtain better performance. It is shown that ${\mu}$-synthesis provides a superior framework for the robust control design of a seeker scan loop system which exhibits robust performance. The proposed robust control system satisfies design requirements, and especially shows good scanning performances for conical and rosette scan patterns despite parametric uncertainty in real system model.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.1
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• pp.35-44
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• 1996

A design method for a teleoperator robot system is presented in this paper. The control system consists of two phases; approach phase and contact one. The end-effector position of the estimated slave robot and the contact force between the end-effector and wall are displayed on the monitors at control site, using which the operator controls the teleoperator system. The approach phase controller is designed using Smith's principle and the contact one designed based upon the structured singular value ${\mu}$ in order to increase the robustness of the system. The uncertainatices such as communication time delay and the variations of system parameters are considered as a muliplicative pertubation. Computer simulations are conducted in order to evaluate the performance of the proposed design method. It is found that desirable control performance, especially in the contact phase, is obtained if the control mode is switched into contact phase when the estimated position of the slave robot end-effector is in front of the wall.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.11
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• pp.1082-1088
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• 2004

This paer presents a feedback-controlled, MEMS-fabricated microaccelerometer($\mu$XL). The $\mu$XL has received much commercial attraction, but its performance is generally limited. To improve the open-loop performance, a feedback controller is designed and experimentally evaluated. The feedback controller is applied to the x/y-axis $\mu$XL fabricated by sacrificial bulk micromachining(SBM) process. Even though the resolution of the closed-loop system is slightly worse than open-loop system, the bandwidth, linearity, and bias stability are stability are significantly improved. The noise equivalent resolution of open-loop system is 0.615 mg and that of closed-loop system is 0.864 mg. The bandwidths of open-loop and closed-loop system are over 100Hz. The input range, non-linearity and bias stability are improved from $\pm10\;g\;to\;\pm18g$, from 11.1%FSO to 0.86%FSO, and from 0.221 mg to 0.128 mg by feedback control, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.1899-1909
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• 2000

This paper proposes a new $H_{\infty}$ yaw moment control scheme using brake torque switching for improving vehicle performance and stability especially in high speed driving. In the scheme, one wheel is selected, depending on the vehicle states, at which a brake torque for control is applied. Steering angles are modeled as a disturbance to the system and the $H_{\infty}$ controller is designed to minimize the difference between the performance of the vehicle and that of the desired model. Its performance robustness as well as stability robustness to system parameter variations is assured through ${\mu}$-analysis. Various simulations with a nonlinear 8-DOF vehicle model show that proposed controller enhances the vehicle performance and stability under disturbances and parameter variations as well as under the normal driving condition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12C
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• pp.255-260
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• 2001

This paper describes the design of the Register Controlled DLL(Delay-Locked Loop) that achieves fast locking and low Power consumption using a new locking algorithm. A fashion for a fast locking speed is that controls the two controller in sequence. The up/down signal due to clock skew between a internal and a external clock in phase detector, first adjusts a large phase difference in coarse controller and then adjusts a small phase difference in fine controller. A way for a low power consumption is that only operates one controller at once. Moreover the proposed DLL shows better jitter performance Because using the lock indicator circuit. The proposed DLL circuit is operated from 50MHz to 200MHz by SPICE simulation. The estimated power dissipation is 15mA at 200MHz in 3.3V operation. The locking time is within 7 cycle at all of operating frequency.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.148-156
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• 2013

This paper suggests a multi-level and multi-output SMPS based on a shared digital logic controller through independently operating in each dedicated time periods. Although the shared architecture can be devised with small area and high efficiency, it has critical drawbacks that real-time control of each DPWM generators are impossible and its output voltage can be unstable. To solve these problems, a real-time current compensation scheme is proposed as a solution. A current consumption of the core block and entire block with four driver buffers was simulated about 4.9mA and 30mA at 10MHz switching frequency and 100MHz core operating frequency. Output voltage ripple was 11 mV at 3.3V output voltage. Over/undershoot voltage was 10mV/19.6mV at 3.3V output voltage. The noise performance was simulated at 800mA and 100KHz load regulation. Core circuit can be implemented small size in $700{\mu}m{\times}800{\mu}m$ area. For the verification of proposed circuit, the simulations were carried out with Dong-bu Hitek BCD $0.35{\mu}m$ technology.

• Proceedings of the KIEE Conference
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• 1997.07b
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• pp.587-589
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• 1997

In this paper we design the model following ${\mu}$-synthesis control system for optimal fuel-injection of diesel engine using genetic algorithms. To do this, we give gain and dynamics parameters to the weighting functions and apply genetic algorithms with reference model to the optimal determination of weighting functions that are given by D-K iteration method which can design ${\mu}$-synthesis controller in the state space. These weighting functions are optimized simultaneously in the search domain selected adequately. The effectiveness of this ${\mu}$-synthesis control system for fuel-injection is verified by computer simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2421-2427
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• 2012

This paper is discussed the design on non-linear adaptive attitude controller for quadrotor UAV. Quadrotor UAV featured to have four rotor, required the special controller to compensate for the model parameter uncertainties as the unstable nonlinear system. In this research, we designed the adaptive controller to compensate for the payload changes even though it is changed with industrial applications. Especially, based on the mathematical model of UAV, non-linear adaptive controller is suggested and the stability is verified using the Lyapunov function and finally proved its performance and effectiveness of update laws with various payload by simulation.

• Journal of Power System Engineering
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• v.17 no.3
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• pp.72-81
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• 2013

Many articles have been published about a 2-degree of freedom model that includes the lateral and yaw motions for controller synthesis in intelligent transport system applications. In this paper, a 3-degree of freedom linear model that includes the roll motion is developed to design a robust steering controller for lane following maneuvers using ${\mu}$-synthesis. This linear perturbed system includes a set of parametric uncertainties in cornering stiffness and unmodelled dynamics in steering actuators. The state-space model with parametric uncertainties is represented in linear fractional transformation form. Design purpose can be obtained by properly choosing the frequency dependent weighting functions. The objective of this study is to keep the tracking error and steering input energy small in the presence of variations of the cornering stiffness coefficients. Furthermore, good ride quality has to be achieved against these uncertainties. Frequency-domain analyses and time-domain numerical simulations are carried out in order to evaluate these performance specifications of a given vehicle system. Finally, the simulation results indicate that the proposed robust controller achieves good performance over a wide range of uncertainty for the given maneuvers.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.6
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• pp.1-7
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• 2008

FlexRay is a new standard of network communication system which provides a high speed serial communication, time triggered bus and fault tolerant communication between electronic devices for future automotive applications. FlexRay communication controller (CC) is the core of the FlexRay protocol specification. In this paper, we first design the FlexRay CC protocol specification and function parts using SDL (Specification and Description Language). Then, the system is re-designed using Verilog HDL based on the SDL source. The FlexRay CC system was synthesized using Samsung $0.35\;{\mu}m$ technology. It is shown that the designed system can operate in the frequency range above 80 MHz. In addition, to show the validity of the designed FlexRay system the FlexRay system is combined with sound source localization system in Robot applications. The combined system is implemented using ALTERA Excalibur ARM EPXA4F672C3. It is shown that the implemented system operates successfully.