• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.623-629
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• 2002

The spectrum of impulse response signal from an impulse hammer testing is widely used to obtain frequency response function(FRF) of the structure. However the FRFs obtained from impact hammer testing have not only leakage errors but also finite record length errors when the record length for the signal processing is not sufficiently long. The errors cannot be removed with the conventional signal analyzer which treats the signals as if they are always steady and periodic. Since the response signals generated by the impact hammer are transient and have damping, they are undoubtedly non-periodic. It is inevitable that the signals be acquired for limited recording time, which causes the finite record length error and the leakage error. In this paper, the errors in the frequency response function of multi degree of freedom system are formulated theoretically. And the method to remove these errors is also suggested. This method is based on the optimization technique. A numerical example of 3-dof model shows the validity of the proposed method.

• 한국소음진동공학회논문집
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• 제12권10호
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• pp.792-798
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• 2002

The spectrum of impulse response signal from an impulse hammer testing is widely used to obtain frequency response function (FRF) of the structure. However the FRFs obtained from impact hammer testing have not only leakage errors but also finite record length errors when the record length for the signal processing is not sufficiently long. The errors cannot be removed with the conventional signal analyzer which treats the signals as if they are always steady and periodic. Since the response signals generated by the impact hammer are transient and have damping, they are undoubtedly non-periodic. It is inevitable that the signals be acquired for limited recording time, which causes the finite record length error and the leakage error. In this paper, the errors in the frequency response function of multi degree of freedom system are formulated theoretically. And the method to remove these errors is also suggested. This method is based on the optimization technique. A numerical example of 3-dof model shows the validity of the proposed method.

• Journal of Power Electronics
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• 제3권2호
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• pp.115-123
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• 2003

This paper presents analysis, design and simulation for the indirect field orientation control (IFOC) of induction machine drive system. The dynamic performance of the IFOC under nominal and detuned parameters of the induction machine is established. A conventional proportional plus integral-derivative (PI-D) two-degree-of-freedom controller (2DOFC) is designed and analysed for an ideal IFOC induction machine drive at nominal parameters with the desired dynamic response. Varying the induction machine parameters causes a degredation in the dynamic response for disturbance rejection and tracking performance with PI-D 2DOF speed controller. Therefore, conventional controllers can nut meet a wide range of speed tracking performance under parameter variations. To achieve high- dynamic performance, a proposed robust fuzzy logic controllers (RFLC) for d-axis rotor flux, d-q axis stator currents and rotor speed have been designed and analysed. These controllers provide robust tracking and disturbance rejection performance when detuning occurres and improve the dynamic behavior. The proposed REL controllers provide a fast and accurate dynamic response in tracking and disturbance rejection characteristics under parameter variations. Computer simulation results demonstrate the effectiveness of the proposed REL controllers and a robust performance is obtained fur IFOC induction machine drive system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 D
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• pp.2631-2633
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• 2004

This paper describes the construction of a half sphere screen driving tilting simulator that can perform six degree-of-freedom( DOF) motions simmulator to a tilting train. The mathematical equations of Tilting Train dynamics are first derived from the 6-DOF bicycle model and incorporated with the bogie. carbody, and suspension subsystems. The equations of motion are then programmed by visual C++ code. To achieve the simulator functions. a motion platform that is constructed by six electric-driven actuators is designed. and its kinetics/inverse kinetics analysis is also conducted. Driver operation signals such as carbady angle, accelerator. and tilting positions are measured to trigger the Tilting dynamics calculation and further actuate the cylinders by the motion platform control program. In addition. a digital PID controller is added to achieve the stable and accurate displacements of the motion platform. The experiments prove that the designed simulator is adequate in performing some special rail mad driving situations discussed in this paper.

• 한국인터넷방송통신학회논문지
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• 제11권5호
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• pp.1-9
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• 2011

오늘날에는 모바일 스마트 기기를 많이 사용해본 소비자들이 무선 연결 방식과 같은 보다 편리하고 스마트한 가정용 전자기기의 연결성을 기대하고 있기 때문에 기존의 전기선을 다른 지능적인 연결방법으로 대체하는 것이 필요하다. 이 연구에서는 양방향 CEC 제어 구조를 새롭게 제안하여 밀리미터 밴드 이미지 전송 시스템에서 제어능력을 단방향에서 양방향으로 확장하는 것을 목적으로 하는데, 이는 2자유도 제어 능력이 HDMI 인터페이스 시스템에서 보다 지능적인 편리성을 제공하기 때문이다. 실험연구를 통해 1080p 풀 HD 이미지 스트림에 대해서 3.0 Gbps의 전송 성능 결과를 보여 지능적 2 DOF CEC 인터페이스를 보유한 밀리미터 밴드의 진보된 이미지 전송 솔루션으로서 제안된 시스템의 유용성을 보인다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2000년도 춘계학술대회 학술발표 논문집
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• pp.138-141
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• 2000

공정제어시스템을 위한 제어기로써 현재까지는 PID 제어기가 보편화되어 적용되어 왔으나 비선형 시스템이나 복잡한 시스템 제어를 위해서는 목표치 추종특성이 우수하며 환경이나 공정 파라미터변화에 둔감하여 외란에 대한 영향이 적은 제어기가 요구된다. PID 제어기로는 이러한 목적을 달성하는 데에 한계가 있기 때문에 이를 해결하기 위한 연구들이 활발히 수행되어 목표치 추종성능과 외란 억제를 동시에 만족토록 하는 다양한 2자유도 PID 제어시스템들이 제안되었고, 본 연구에서는 먼저 현재까지 제안된 2자유도 PID 제어시스템들 중 제어성능이 가장 우수한 것으로 나타난 목표치 필터형 2자유도 PID 제어시스템(Target Value Filter Type 2-DOF PID Control System: 이하 TVF-2DOF) [2]보다 우수한 2자유도PID 제어시스템을 제안하고, 이를 바탕으로 2자유도 선행필터(Pre-Filter)부분에 지능제어기법의 하나인 퍼지로직을 적용함으로써 PID 제어기의 장점과 퍼지로직의 장점을 동시에 활용하는 지능형 튜닝(Tuning)기법에 관한 연구를 수행하였고, 지능형 시스템이 2자유도 PID 제어시스템들보다 목표치 추종 성능 및 외란억제효과가 우수하다는 사실을 컴퓨터 시뮬레이션을 통해 입증하였다. 시스템으로는 유량 제어 밸브가 사용되었다.

• 로봇학회논문지
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• 제9권1호
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• pp.11-19
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• 2014

In this paper, an external torque estimation problem in one-degree-of-freedom (1-DOF) flexible-joint robot equipped with a joint-torque sensor is revisited. Since a sensor torque from the joint-torque sensor is distorted by two dynamics having a spring connection, i.e., motor dynamics and link dynamics of a flexible-joint robot, a model-based estimation, rather than a simple linear spring model, should be required to extract external torques accurately. In this paper, an external torque estimation algorithm for a 1-DOF flexible-joint robot is proposed. This algorithm estimates both an actuating motor torque from the motor dynamics and an external link torque from the link dynamics simultaneously by utilizing the flexible-joint robot model and the Kalman filter estimation based on random-walk model. The basic structure of the proposed algorithm is explained, and the performance is investigated through a custom-designed experimental testbed for a vertical situation under gravity.

• Korean Chemical Engineering Research
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• 제49권5호
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• pp.565-570
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• 2011

시간지연이 없는 다양한 범주의 안정, 적분, 불안정 공정에 대하여 비례-적분-미분(PID) 제어기의 해석적 조율 방법을 제안하였다. 2자유도 제어구조와 내부모델 제어에 기반한 제안된 방법은 설계가 간단하고 직접적이며 공정산업에 쉽게 구현할 수 있어 강화된 설정점 추종과 외란제거 성능을 얻는데 유용하게 사용될 수 있다. 몇몇 대표적 공정에 대하여 강건성을 같게 유지하면서 기존 설계 방법과 비교한 결과, 제안된 방법의 우수한 폐루프 성능을 확인하였다.

• International Journal of Aeronautical and Space Sciences
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• 제14권2호
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• pp.152-161
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• 2013

This paper presents a control effectiveness analysis of the hawkmoth Manduca sexta. A multibody dynamic model of the insect that considers the time-varying inertia of two flapping wings is established, based on measurement data from the real hawkmoth. A six-degree-of-freedom (6-DOF) multibody flight dynamics simulation environment is used to analyze the effectiveness of the control variables defined in a wing kinematics function. The aerodynamics from complex wing flapping motions is estimated by a blade element approach, including translational and rotational force coefficients derived from relevant experimental studies. Control characteristics of flight dynamics with respect to the changes of three angular degrees of freedom (stroke positional, feathering, and deviation angle) of the wing kinematics are investigated. Results show that the symmetric (asymmetric) wing kinematics change of each wing only affects the longitudinal (lateral) flight forces and moments, which implies that the longitudinal and lateral flight controls are decoupled. However, there are coupling effects within each plane of motion. In the longitudinal plane, pitch and forward/backward motion controls are coupled; in the lateral plane, roll and side-translation motion controls are coupled.

• International Journal of Control, Automation, and Systems
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• 제5권1호
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• pp.15-23
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• 2007

In surveillance, monitoring, and target tracking operations, high-resolution images should be obtained even if the target is in a far distance. Frequent movements of vehicles such as boats degrade the image quality of onboard camera systems. Therefore, stabilizer mechanisms are required to stabilize the line of sight of boatboard camera systems against boat movements. This paper addresses design and implementation of a strapdown boatboard camera stabilizer. A two degree of freedom(DOF)(pan/tilt) robot performs the stabilization task. The main problem is divided into two subproblems dealing with attitude estimation and attitude control. It is assumed that exact estimate of the boat movement is available from an attitude estimation system. Estimates obtained in this way are carefully transformed to robot coordinate frame to provide desired trajectories, which should be tracked by the robot to compensate for the boat movements. Such a practical robotic system includes actuators with fast dynamics(electrical dynamics) and has more degrees of freedom than control inputs. Backstepping method is employed to deal with this problem by extending the control effectiveness.