• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2000.04b
• /
• pp.431-438
• /
• 2000

The cost function consists of the weighting functions concerning the structural responses to be controlled and the controller capability. Therefore, the control efficiency depends on the characteristics of the weighting functions. The objective of this paper is the comparative study of the time domain control strategies of LQR and LQG and the frequency domain strategy of H₂ by setting the equivalent weighting functions to the all control strategies. As a result of analysis, LQR strategy is found to be more efficient than other strategies in terms of the response reduction. but the control force is found to be a little highter. As LQG can compensate the limitation of LQR that all state variables should be identified, LQG is more acceptable algorithm than LQR. Furthermore LQG shows a good performance both in the response reduction and the control force. Finally H₂ algorithm is employed to illustrate the importance of weighting filters considering the frequency characteristics of the response and the controller. It Is shown that the H₂ algorithm is found to be the most effective one for the response control with a little control force having a low frequency band.

• 제어로봇시스템학회:학술대회논문집
• /
• 2002.10a
• /
• pp.101.6-101
• /
• 2002

The LQG/LTR controller is a robust and stable control which is systematic method with a view of engineering. And the scheme is adopted for the design of the controller to reduce the effects of the disturbances. In this paper, We develop an algorithm that decides the distance and directions between the guide line that is made by a series of magnets and MR sensors of vehicle. LQG/LTR and Controller Design of Lateral Control System for a vehicle 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 controller provides more robustness property for t...

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1996.10a
• /
• pp.338-344
• /
• 1996

In this paper, a semi-active suspension adapting to road variation which also considers the frequency snesitivity of human is proposed. First, a road adapting controller composed of system identification and LQG control is designed. Using the extended least squares method, the road property is estimated by system identification as it varies, and the LQG controller considering the estimated road property and the frequency sensitivity of human is designed. Next, the semi-active suspension is made, which tracks the performance of the active suspension with the road adapting controller. Through numerical simulation, the performance of the proposed semi-active suspension is compared with that of a non-adaptive semi-active suspension with frequency-shaped performance index. As a result, we see that the road adapting semi-active suspension has better performance.

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

• Journal of Advanced Navigation Technology
• /
• v.21 no.1
• /
• pp.43-49
• /
• 2017

Generally, loop filter based scalar tracking loops (LF-STL) have been used for global positioning system (GPS) signal tracking algorithm. This paper introduces the accuracy and robustness of linear-quadratic-Gaussian based vector tracking loop (LQG-VTL) algorithm instead of LF-STL. To verify the accuracy of LQG-VTL, we confirm that the measurements estimation errors of the LQG based scalar tracking loops (LQG-STL) are improved by more than 60 % compared to LF-STL. Also, when LQG-VTL is used, measurements estimation errors decrease compared to LQG-STL, and position/velocity estimation errors also decrease as the number of satellites increases. To verify the robustness of LQG-VTL, we confirm that LQG-VTL can estimate position/velocity and measurements successively compared to LF-STL in temporal signal attenuation of 30 dB-Hz during 4 seconds.

• Proceedings of the KIEE Conference
• /
• 1998.07c
• /
• pp.1024-1026
• /
• 1998

In this paper we present a Neural network approach to select weighting matrices of Linear-Quadratic-Gaussian (LQG) controller for TCSC control. The selection of weighting matrices is usually carried out by trial and error. A weighting matrices of LQG control selected effectively using Neural network. It is shown that simulation results in application of this method to one machine infinite bus system are satisfactory.

• Journal of the Korean Society of Industry Convergence
• /
• v.25 no.2_2
• /
• pp.193-198
• /
• 2022

In this paper, we introduce the improved control method are communicated between a master and a slave robot in the teleoperation systems. When the master and slave robots are located in different places, time delay is unavoidable under the network environment and it is well known that the system can become unstable when even a small time delay exists in the communication channel. The time delay may cause instability in teleoperation systems especially if those systems include haptic feedback. This paper presents a control scheme based on the estimator with virtual master model in teleoperation systems over the network. As the behavior of virtual model is tracking the one of master model, the operator can control real master robot by manipulating the virtual robot. And LQG/LTR scheme was adopted for the compensation of un-modeled dynamics. The approach is based on virtual master model, which has been implemented on a robot over the network. Its performance is verified by the computer simulation and the experiment.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.1207-1210
• /
• 2003

In this paper, studied traveling by ummaned vehicles using MPC sensor.Explain what is MPC sensor and also is threaded how on vehicles. Made use of PID controller and LQG/LTR controller that is used much in present industrial circles for control of this.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.6
• /
• pp.1399-1411
• /
• 1994

A model helicopter has more versatile flight capability than the fixed-wing aircraft and it can be used as an unmaned vehicle in hazardous area. A helicopter, similar to other aircrafts, is an unstable, multi-input multi-output nonlinear system exposed to strong disturbance. So it should be controlled by robust control theories that can be applied to multivariable systems. In this study, motion equations of hovering are established, linearized and transformed into a state equation form. Various parameters are measured and calculated in other to obtain the stability derivatives in the state equation. Hovering flight controller is designed using the digital LQG/LTR(Linear Quadratic Gaussian/Loop Transfer Recovery) control theory. The designed controller is tested by the nonlinear simulations and implemented on an IBM-PC/386. Experiments were carried out on a model helicopter attached to the 3-DOF gimbal. The designed controller showed satisfactory hovering capability to maintain the hovering for more than 40 seconds.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.320-320
• /
• 2000

In this paper, a temperature controller of a test plate for semiconductor is developed using LQG/LTR methodology. The liquid is heated or cooled in a tank by a heater of a cooler. The controller controls the flow of heated or cooled liquid in the plate by controling an electronic valve. The developed controller is applied to the plate designed for function test of a semiconductor under high or low temperature environment. As a result, control using the heater and the cooler together shows better control performance than using the heater or the cooler separately.