• Smart Structures and Systems
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• 제3권2호
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• pp.147-172
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• 2007

The present paper is concerned with the design of distributed sensors and actuators. Strain type sensors and actuators are considered with their intensity continuously distributed throughout a continuous structure. The sensors measure a weighted average of the strain tensor. As a starting point for their design we introduce the concept of collocated sensors and actuators as well as the so-called natural output. Then we utilize the principle of virtual work for an auxiliary quasi-static problem to assign a mechanical interpretation to the natural output of the sensors to be designed. Therefore, we take the virtual displacements in the principle of virtual work as that part of the displacement in the original problem, which characterizes the deviation from a desired one. We introduce different kinds of distributed sensors, each of them with a mechanical interpretation other than a weighted average of the strain tensor. Additionally, we assign a mechanical interpretation to the collocated actuators as well; for that purpose we use an extended body force analogy. The sensors and actuators are applied to solve the displacement tracking problem for continuous structures; i.e., the problem of enforcing a desired displacement field. We discuss feed forward and feed back control. In the case of feed back control we show that a PD controller can stabilize the continuous system. Finally, a numerical example is presented. A desired deflection of a clamped-clamped beam is tracked by means of feed forward control, feed back control and a combination of the two.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.331-336
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• 2012

This paper proposes a new type of high-frequency directional valve controlled by the piezostack actuator associated with displacement amplifier. As a first step, a dynamic model of directional valve which can operate at 200 Hz with a flow rate of 12 l/min is derived by considering pressure drop and flow force. As a second step, an appropriate piezostack is selected by considering actuation force as well as field-dependent displacement. Subsequently, in order to control spool displacement and flow rate a proportional-derivative (PD) controller is designed based on the $3^{rd}$-order valve system. Control performances such as sinusoidal trajectory tracking of the spool displacement in time domain are evaluated. In addition, the field-dependent flow rate is also presented to verify the required performance of the valve system.

• 한국소음진동공학회논문집
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• 제22권10호
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• pp.1020-1026
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• 2012

This paper proposes a new type of high-frequency directional valve controlled by the piezostack actuator associated with displacement amplifier. As a first step, a dynamic model of directional valve which can operate at 200 Hz with a flow rate of 12 litter/min is derived by considering pressure drop and flow force. As a second step, an appropriate piezostack is selected by considering actuation force as well as field-dependent displacement. Subsequently, in order to control spool displacement and flow rate a proportional-derivative(PD) controller is designed based on the 3rd-order valve system. Control performances such as sinusoidal trajectory tracking of the spool displacement in time domain are evaluated. In addition, the field-dependent flow rate is also presented to verify the required performance of the valve system.

• 대한기계학회논문집
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• 제17권9호
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• pp.2373-2380
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• 1993

This paper addresses the design procedure and testing result of a servo driven pan/tilt device which is capable of tracking arbitrary movement of a specified target object. In order to achieve real-time acquisition of feedback signal, a 2 degree-of freedom non-contact type displacement follower has been employed in stead of vision camera. The performance of the designed system is tested for different target velocities and control gains. The test result shows the satisfactory performance to be adopted as an effective tool for visual transfer in the context of teleoperation.

• 제어로봇시스템학회논문지
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• 제1권1호
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• pp.58-62
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• 1995

Necessarily, it is required to analyze interfacial mechanism between tire and road for understanding tire wear, vehicle tracking and breaking. Therefore, there have been some efforts to measure 3-axis pressure and 2-axis displacement on tire road interface. But it was so hard to couple precisely measuring sensor and desired point on tire tread pattern block that it was impossible to analyze the mechanism on commercial tire with tread pattern. To overcome such a problem, a on-line measurement system is proposed in this paper. And an automatic control system is designed to test the tire with similar configuration of real vehicle driving.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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• pp.405-406
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• 2007

In this paper, we propose feature extraction and tracking algorithm using multi resolution in 2-dimensional wavelet domain. Feature extraction selects feature points using 2-level wavelet transform in interested region. Feature tracking estimates displacement between current frame and next frame based on feature point which is selected feature extraction algorithm. Experimental results show that the proposed algorithm confirmed a better performance than the existing other algorithms.

• 한국지반환경공학회 논문집
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• 제4권3호
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• pp.79-88
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• 2003

비균질 다공성 매질을 통과하는 선형 흡착 용질의 공간적 거동에 대한 특성이 수치적 기법을 통해 분석되었다. 공간적으로 서로 상관된 투수계수의 대수적 분포를 지구통계학적 기법인 TBM(Turning Bands Method)을 사용하여 2차원 공간 내에 발생시켰으며, 이를 통한 지하수 흐름의 수리수두분포와 유속벡터장은 정상상태의 포화된 2차원 지하수 흐름 방정식에 Galerkin 유한요소법을 적용하여 계산하였다. 또한, 용질이동에 대한 수치모의는 시간간격을 자동으로 보정해주는 CD(constant displacement)기법이 포함된 난보모형(Random Walk Particle Tracking Model, RWPTM)을 통해 수행되었다. 본 연구에서 용질의 공간적 거동의 특성은 종방향 질량중심 이동거리, 종방향 공간 퍼짐 모멘트 그리고 용질분포의 종방향 왜곡계수를 통해 분석되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.454-457
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• 1995

In optical disc system, tracking actuator is consisted of coarse actuator and fine tracking actuator. This, two-stage actuator, requires many devices and two servos for large stroke and precisional displacement. These complicate configuration increases moving mass. So dynamic characteristics become bad, that is, sensitivity of high frequency gain decrease. In this paper, frequency performance is willing to be better as so one dimensional tracking actuator is designed. In order to investigate the performance of the proposed tracking actuator, the Bode diagram is plotted with Dynamic analyzer and friction characteristic is explained. Finally, tracking error performance is ins investigated into 0.1 .mu.m resolution with MATLAB simulation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.775-778
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• 1996

In this research, the robustness of a seam tracking for the automatic welding system is studied. The laser displacement sensor is used as a seam finder. X-Y moving table drived by ac servo motor controls the position and velocity of the torch-and-sensor part. However, dc servo motor is used to control the position and velocity of the torch. The sensor locates ahead of torch to preview the weld line, and brings about the inaccuracy on the torch tracking. To enhance the robustness on this system against the influence of disturbances and model uncertainty, H$\_$.inf./ control is applied to the angular motion of torch. The simulation shows that the tracking accuracy improved significantly. Also, experimental results give a good performance of H$\_$.inf./ control strategy to the automatic seam tracking system for the welding.

• 정보처리학회논문지B
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• 제9B권1호
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• pp.99-104
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• 2002

기존의 물체추적기법은 템플릿 매칭, 물체의 경계선 재 검출, 물체의 움직임 정보 등을 사용하여 수행되었다. 그러나, 템플릿 매칭의 경우 많은 계산 시간을 요구하고, 경계선을 재 검출하는 경우 윤곽선이 잘못 설정되는 경우가 있으며, 물체의 움직임 정보를 사용하는 경우에는 움직이는 카메라에서 움직이는 물체만을 추적하기가 쉽지 않은 단점이 있다. 본 논문에서는 투영된 모션과 히스토그램 인터섹션을 이용한 강건한 물체추적 방법을 제안한다. 초기 객체추출은 영상분할 후 영역선택을 통하여 구성하고 선택된 객체를 가로 및 세로의 밝기 값을 1차원 신호로 투영하여 객체의 개략적인 평행이동 벡터를 추정한다. 추정된 변위를 기준으로 하여 객체의 가능한 회전 및 스케일에 대한 템플릿을 구성하고, 이들에 대하여 개선된 히스토그램 인터섹션을 사용하여 물체 추적을 수행한다. 제안한 알고리즘의 강건한 물체추적 성능을 실험에 의하여 확인하였다.