• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.113-113
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• 2000

A robust adaptive technique for the longitudinal control of a platoon of automated vehicles is presented. A nonlinear model is used to represent the vehicle dynamics of each vehicle within the platoon. The external disturbance such as wind gust and a disturbance term due to engine transmission variations and so on are considered. The state observer is used to avoid direct measurement of the relative velocity or acceleration between the controlled and leading vehicles or the controlled vehicle's acceleration. It is shown that platoon stability can be recovered in operation even if a speed dependent spacing policy is adopted, which incorporates a constant time headway in addition to the constant distance. The simulation results demonstrate excellent tracking even in the presence of disturbances.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.5
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• pp.214-221
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• 2015

In this paper, we present robust estimation and detection algorithms for discrete-time switched linear systems whose output measurements are corrupted by noises. First, a mode estimation algorithm is proposed based on the minimum distance criterion. Then, state variables are also observed under the active mode estimate. Second, a detection algorithm is constructed to detect the mode switching of the switched system. With the boundedness of measurement noise, the proposed estimation algorithm returns the exact active mode and approximate state information of the switched system. In addition, the detection algorithm can detect the switching time within a pre-determined time interval after the actual switching occurred.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.2
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• pp.121-128
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• 2011

As high precision industries such as semiconductor, TFT-LCD manufacturing and MEMS continue to grow, the demand for higher DOF precision stages has been increasing. In general, the stages should accommodate a prescribed range of payloads in order to position various precision manufacturing/inspection instruments. Therefore a nonlinear controller using sliding motion is developed, which bears mass perturbation and makes the upper plate of the stage move in 6 DOF. For the application of the nonlinear control, an observer is also developed based on expected noise covariance. To eliminate the steady state error of step response, integral terms are inserted into the state-space model. The linear term of the controller is designed using optimization scheme in which parameters can be weighted according to their physical significance, whereas the nonlinear term of the controller is designed using trial and error method. A comprehensive simulation study proves that the designed controller is robust against mass perturbation and completely eliminates steady state errors.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.5
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• pp.907-912
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• 2020

When designing a controller, a motor can have robust and precise control performance only by considering the error of the motor's mathematical model and the disturbance acting on it. For robust and precise control, the mechanical and electrical disturbance observers were designed to estimate the disturbance, and applied to the speed controller and current controller designed as a nominal system. To confirm the control performance of the designed system, it is applied to a 120 [W] class BLDC motor, and the result of the speed tracking control overcomes disturbances, the steady state error converges to zero, and the asymptotically stable result can be confirmed.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2164-2169
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• 2005

SFFS(Solid Freeform Fabrication System) can quickly makes models and prototype parts from 3D computer-aided design (CAD) data. Three dimensional printing(3DP) is a kind of the solid freeform fabrication. The 3DP process slices the modeling data into the 50-200um along to z axis. And we pile the powder and make the manufactures. A manufacture is made by the SFFS has the precision of the 50um. Therefore the x-y table of SFFS to move a printhead must be the system that has a high speed and accuracy. So we proposed the SMCSPO algorithm for SFFS. The major contribution is the design of a robust observer for estimating the state and the perturbation of the timing belt system, which is combined with a robust controller. The control performance of the proposed algorithm is compared with PD control by the simulation and the experiment. The control algorithm of the SFFS is presented in the office environment. The system between control system and printhead for the SFFS is also integrated

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.589-597
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• 2011

In this paper, optimal tuning of a cross-coupled controller linked with the feedforward controller and the disturbance observer is studied to improve contouring and tracking accuracy as well as robustness against disturbance. Previously developed integrated design and optimal tuning methods are applied for developing the robust tuning method. Strict mathematical modeling of the multivariable system is formulated as a state-space equation. Identification processes of the servomechanism are conducted for mechanical servo models. An optimal tuning problem to minimize both the contour error and settling time is formulated as a nonlinear constrained optimization problem including the relevant controller parameters of the servo control system. Constraints such as relative stability, robust stability and overshoot, etc. are considered for the optimization. To verify the effectiveness of the proposed optimal tuning procedure, linear and circular motion experiments are performed on the xy-table. Experimental results confirm the control performance and robustness despite the variation of parameters of the mechanical subsystems.

• Journal of Drive and Control
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• v.14 no.2
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• pp.45-51
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• 2017

Semi-submersible drilling rigs are offshore plants that perform functions such as ocean exploration for oil and gas acquisition, drilling and production, and storage and unloading of crude oil and gas. Semi-submersible drilling rigs use watertight dampers as emergency buoyancy holders. Since the watertight damper is an emergency shutoff device, it is mainly driven by a pneumatic driving system that can operate without a power supply. The pneumatic driving system has highly non-linear characteristics due to compressibility of air and external disturbance such as static and Coulomb friction. In this paper, a new control algorithm is proposed for a watertight damper driving system based on the sliding mode control with a disturbance observer. To evaluate control performance and robust stability of the designed controller, the control results were compared with the results obtained using the state feedback controller. As a result, it was confirmed that the pneumatic driving system for driving the watertight damper using the sliding mode controller with a disturbance observer can obtain excellent control performance against the parameter changes and the disturbance input.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.270-273
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• 1996

A scheme of observer-based MFAC(Model Following Acceleration Control) system is proposed for the robustness control of DC servo position control systems. The proposed system is composed of LMFC, variable structure feedback controller, and reduced-order state observer. As the servo motor is controlled by the acceleration command, the total servo system becomes the acceleration control system. Simulation results show that the proposed system have robust properties against parameter variations and external disturbances.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.1-6
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• 2003

The torque is an important measure that represents the performance of a particular engine. Furthermore the information of engine torque can be used as a primary feedback parameter in modem engine management system. In this paper, a methodology is proposed for torque estimation of SI-engine. Since the proposed method uses cylinder pressure sensor, the torque can be estimated in a simple manner. The indicated torque is estimated from the peak pressure and its location, and the load torque is observed by the state observer based on the estimated indicated torque. The proposed method is accurate and robust against the variations that affect the torque production such as spark timing, mass air flow and others. This torque estimation method may be an alternative solution to the use of engine torque maps in a modem torque-based engine management system.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.2
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• pp.135-143
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• 1992

A novel sliding mode control with disturbance observer for position control of DC servo motor is presented. The conventional sliding mode controller changes the control structure depending on the state of switching surface and consequently, the control law is discontinuous and theoretically chatters at an infinite frequency. To overcome this problem in view of the practical implementation, the disturbance observer is used to compensate the effects of the parameter variations and the load disturvances. We can obtain the performance predetermined by the switching surface with continuous control law while the controlled system remains robust. The performance of the proposed controller with that of the conventional sliding mode controller through digital computer simulation and experiment.