• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.496-499
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• 2002

The LQG/LTR controller is a robust and stable control which is systematic method with a view of engineering. And the H$^{\infty}$ scheme is adopted for the design of the controller to reduce the effects of the disturbances. In this paper, LQG/LTR and H$^{\infty}$ Controller Design of Lateral Control System for an Automobile is developed with 3 DOF (degree-of-freedom) model. The performance has been compared for the employed two types of controllers via computed simulations. The results show that the H$^{\infty}$ controller provides more robustness property for the disturbances and lower control input.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.318-321
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• 2002

The LQG/LTR controller is a robust and stable control which is systematic method with a view of engineering. And the H$^{\infty}$ scheme is adopted for the design of the controller to reduce the effects of the disturbances. In this paper, LQG/LTR and H$^{\infty}$ Controller Design of Lateral Control System for an Automobile is developed with 3 DOF (degree-of-freedom) model. The performance has been compared for the employed two types of controllers via computed simulations. The results show that the H$^{\infty}$ controller provides more robustness property for the disturbances and lower control input.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.293-298
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• 1993

In ground vehicles, the increasing demand for safety and ride comfort which are trade-off relation, especially at high speeds, has led to the development od actively controlled suspensions. The LQG/LTR controller can be used to design a robust feedback control system that deals with disturbance rejection properties as well as insensitivity to modelling errors and sensor noise. And when the disturbance can not be measured but is limited within a certain frequency range, a bandpass feedback to eliminate the disturbance response can be used. In this paper, hybrid controller cosisted of bandpass feedback controller and LQG/LTR controller is applied to a quarter-car model moving on a randomly profiled road. The random road profile considered as colored noise is shaped from white noise by use of shaping filter. The performance of the hybrid control system is compared with that of an LQG/LTR controlled system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.4
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• pp.102-108
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• 2011

LQG/LTR control scheme is applied to the two axes stage using piezoelectric actuator for tracking reference input and suppressing hysteresis effect in this paper. The plant is combined with an integrator to improve the tracking ability. LQG/LTR controller is designed by making desirable target filter loop remove all poles except for an integrator included in new design plant model and loop transfer recovery. Decoupler in the shape of FIR filter is added to remove the coupling effect between the two axes motion and so feedback control loop is designed independently for the each axis motion.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.2
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• pp.88-97
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• 1989

In general turret servo system is subject to influnces by disturbances and uncertain modeling errors, which result from large dynamic characteristics and high-spedd operation. In this paper the influences of such disturbances and modeling errors are analyzed quali- tatively for the linerar approximation model of turret servo system, and then LQG/LTR control theory is applied to linear approximation model in order to design a controller which satisfies robustness/stability for the modeling errors. Finally the performance and robustness of designed controller for the given plant are verified through the simulation.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.2
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• pp.67-80
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• 1995

In order to control systems which are dominantly subjected to modeling errors and uncertainties, control strategies must deal with the effect of modeling errors and uncertainties. Since most of control methods based on system mathematical model, such as LQG/LTR method, have been developed mainly focused on stability robustness, they can not smartly improve the transient response disturbed by modeling errors and/or uncertainties. In this research, a fuzzy PID control method is suggested, which can stably improve the transient responses of systems disturbed by modeling errors as well as systems not entirely using mathematical models. So as to assure the effectiveness of suggested control method, computer simulations are accomplished for some example systems, through the comparison of transient responses.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.2
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• pp.157-163
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• 2014

In this paper, a robust MRAC (model reference adaptive control) scheme is applied to control an electrohydraulic positioning system under various loads. The inverse dead-zone compensator in the control system cancels out the dead-zone response, and an integrator added to the controller provides good position-tracking ability. LQG/LTR (linear quadratic Gaussian control with loop transfer recovery) closed-loop model is used as the reference model for learning the MRAC system. LQG/LTR provides a systematic technique to design the linear controller that optimizes the objective function using some compromise between the control effort and the system performance in the frequency domain. Different external load tests are performed to investigate the effectiveness of the designed MRAC system in real time. The experimental results show that the tracking performance of the proposed system is highly accurate, which offers considerable robustness even with a large change in the load.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.5
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• pp.110-120
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• 1994

Due to the increasing demands in comfortable drivability, most motor companies are developing their own unique shift controller to suppress the shift shock induced by gear change. For a typical automatic transmission system, the dynamic constraints of friction clutch was clarified for efficient program development and major factors effecting the shift transient was confirmed by simulation study. The MIMO LQG/LTR controller was designed to control the turbine and corresponding gear speed. By establishing the control strategy recalling transient response during shift the speed controller mentioned above was used as an indirect torque controller. Consequently a new concept for a systematic design method of shift controller applicable to wide-varying systems was suggested which is time efficient and cost efficient saving a lot of experimental study.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.7
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• pp.74-81
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• 1995

In this paper, a composite controller cosisted of bandpass feedback controller and LQG/LTR controller is applied to a quarter-car model moving on a randomly profiled road. The LQG/LTR controller is used to achieve a design transfer toop. A bandpass feedback controller is adopted to eliminate the response due to the disturbance, which generally can not be measured, confined within an interested frequence range. The random road profile considered as colored noise is shaped from white noise by use of shaping filter. The performance of the composite control system is compared with that of an LQG/LTR control system.

• Nuclear Engineering and Technology
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• v.27 no.5
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• pp.730-742
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• 1995

The steam generator feedwater and level control system is designed by two steps of the feedwater control design and the feedback loop controller design. The feedwater sen system is designed by the optimal LQR/LQG approach and then is modified by the LTR method to recover the robustness. The plant characteristics are subject to change with the power variation and these dynamic properties are considered in the design of the feedback controller. All the designs are made in the continuous domain and are digitalized by applying the proper sampling period. The system is simulated for the two cases of power increase and decrease. From the results of simulation, it is found that the controller constants would rather be invariable during the power increase, while for the case of power decrease they should be changed with the power variation to keep the system stability.