• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.366-369
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• 1991

A nonlinear controller based on feedback linearization method is proposed for an electromagnetic suspension system. After exactly linearizing the system with nonlinear feedback, linear control technique is applied. Modeling of stagger typed magnet is introduced and controlled for not only levitation, but guidance. By the feedback linearization, the nonlinear, MIMO system is linearized and decoupled, so we can use linear control law. The simulation of this system control skim is demonstrated. Robustness properties of the proposed controller with respect to the load variations and external disturbance is also analyzed for a multi input multi output system. In this properties, the boundary of variation is proposed.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1352-1364
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• 2013

This paper describes a novel structure for single phase Unified Power Quality Conditioner-Distributed Generation (UPQC-DG) with direct grid connected DC-AC converter for low DC output DG systems which can be used not only for compensation of power quality problems but also for supplying of load power partly. This converter has been composed of one full-bridge inverter, one three winding high frequency transformer with galvanic isolation and two cycloconverters. Proper control based on Input Output feedback Linearization is used to tracking the reference signals. The simulation and experimental results are presented to confirm the validity of the proposed approach.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1228-1233
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• 2005

In this paper, we present a new guidance law for a reusable launch vehicle (RLV) that lands vertically after reentry. In our past studies, a guidance law was developed for a vertical/soft landing to a target point. The guidance law, which is analytically obtained, can regenerate a trajectory against disturbances because it is expressed in the form of state feedback. However, the guidance law does not necessarily guarantee a vertical/soft landing when a dynamical system such as an RLV includes a nonlinear phenomenon owing to the atmosphere of the earth. In this study, we introduce a design of the guidance law for a nonlinear system to achieve a vertical/soft landing on the ground using the exact linearization method and solving the two-point boundary-value problem for the derived linear system. Numerical simulation confirmed the validity of the proposed guidance law for an RLV in an atmospheric environment.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.2 no.1
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• pp.78-82
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• 2002

In this paper, we have studied a numerical stability analysis method for the robust fuzzy feedback linearization regulator using Takagi-Sugeno fuzzy model. To analyze the robust stability, we assume that uncertainty is included in the model structure with known bounds. For these structured uncertainty, the robust stability of the closed system is analyzed by applying Linear Matrix Inequalities theory following a transformation of the closed loop systems into Lur'e systems.

• Journal of Mechanical Science and Technology
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• v.18 no.2
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• pp.203-210
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• 2004

Attitude control law design for spacecraft large angle maneuvers is investigated in this paper. The feedback linearization technique is applied to the design of a nonlinear tracking control law. The output function to be tracked is the quaternion attitude parameter. The designed control law turns out to be a combination of attitude and attitude rate tracking commands. The attitude-only output function, therefore, leads to a stable closed-loop system following the given reference trajectory. The principal advantage of the proposed method is that it is relatively easy to produce reference trajectories and associated controller.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.4
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• pp.283-288
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• 2008

A post-linearization technique for the differrential CMOS LNA is presented. The proposed method uses an additional cross-coupled common-source FET pair to cancel out the third-order intermodulation ($IM_3$) current of the main differential amplifier. This technique is applied to enhance the linearity of CMOS LNA using $0.18-{\mu}m$ technology. The LNA achieved +10.2 dBm IIP3 with 13.7 dB gain and 1.68 dB NF at 2 GHz consuming 11.8 mA from a 1.8-V supply. It shows IIP3 improvement by 6.6 dB over the conventional cascode LNA without the linearizing circuit.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.453-455
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• 1997

일반적으로 제철공정에서 각 공정사이의 철판의 속도와 장력은 브라이드롤을 이용하여 제어하는데 여기서 입력 측의 브라이드롤은 장력을 제어하고 출력 측의 브라이드롤은 공정의 속도를 제어한다. 이와 같은 방법은 시스템 기동의 순간을 포함하여 공정속도의 변경이 있을 경우 제철 공정 상에서는 특히 철판의 높은 탄성에 기인하여 시스템이 상당히 불안정하게 된다. 본 논문에서는 각 전동기가 정해진 역할에 따라 독립적으로 장력 혹은 공정속도를 제어하고 장력의 모델링에서 비선형의 요소를 되먹임하여 원래의 시스템을 선형화시켰고 이때 미분관측기를 이용하였다. 이 제어기의 장점은 무엇보다도 독립적인 역할의 분담으로 인해 다수의 전동기로 확장이 용이하도록 하는 것이다.

• The Journal of Korea Robotics Society
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• v.15 no.3
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• pp.248-255
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• 2020

This paper introduces a Feedback Linearization (FL) controller to eliminate the gyro effect on a quadrotor UAV. In order to control the attitude of the quadrotor, the second model equation was differentiated to the 4-th order to induce the control input to be revealed, and then a new control input was derived based on the attitude transformation equation with a gyro effect. For the initial quick posture control of the quadrotor, the existing yaw control was replaced with a separate controller. The simulation was conducted with an experiment in which FL control to remove the gyro effect was applied to the quadrotor and an experiment without removing the gyro effect, from the experimental results, the maximum error seen in each axial direction of the quadrotor was x = 0.22 m, y = 0.20 m, z = 0.16 m. Through the proposed method, the effect of the FL controller for controlling the gyro effect of the quadrotor was confirmed.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.2116-2124
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• 2018

Magnetic levitation system with the advantages of non-contact, no friction and no wear can satisfy the requirement of high precision and high speed positioning. In this paper, magnetic levitation positioning stage which mainly consists of planar coil and HALBACH permanent magnet array and its control and driving system are designed. Magnetic levitation system is a highly nonlinear and strongly coupled complex system and its control performance can be influenced by the uncertainty and external disturbance. So exact feedback linearization method is used to realize exact linearization and decoupling, and a strategy of sliding mode control based on disturbance observer is proposed to compensate the uncertainty and external disturbance. Detailed proofs of observer's convergence property and system stability are derived. Both the simulation and experiment results verify the effectiveness of sliding mode control algorithm based on disturbance observer.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.110-115
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• 2001

The spherical CVT, intended to overcome some of the limitations of existing CVT designs, is marked by its simple kinematic design, improved efficiency of the shift actuator, and IVT characteristics, i.e., the ability of smooth transition between the forward, neutral, and reverse states without the need for any brakes or clutches. And it has been promised much possibility of energy savings and various applications for small power capacity machinery. Due to the nonlinearity of the spherical CVT shifting dynamics, however the original open-loop system is inherently unstable. Hence a feedback controller is necessary to make the system stable and to achieve effective tracking performance. To do this, we designed a feedback controller that cancels nonlinearities and transforms the original nonlinear system dynamics into a stable and controllable linear one, based on the input-state linearization method.