• Smart Structures and Systems
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• v.3 no.2
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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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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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.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.10
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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.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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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.

• Journal of Institute of Control, Robotics and Systems
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• v.1 no.1
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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.

• Proceedings of the IEEK Conference
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• 2007.07a
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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.

• Journal of the Korean GEO-environmental Society
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• v.4 no.3
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• pp.79-88
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• 2003

This paper presents a numerical study of the spatial behavior of a linear absorbing solute in a heterogeneous porous medium. The spatially correlated log-normal hydraulic conductivity field is generated in a given two-dimensional domain by using the geostatistical method (Turning Bands algorithm). The velocity vector field is calculated by applying the two-dimensional saturated groundwater flow equation to the Galerkin finite element method. The simulation of solute transport is carried out by using the random walk particle tracking model with CD(constant displacement) scheme in which the time interval is automatically adjusted. In this study, the spatial behavior of a solute is analyzed by the longitudinal center-of-mass displacement, longitudinal spatial spread moment and longitudinal plume skewness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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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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• 1996.10b
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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.

• The KIPS Transactions:PartB
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• v.9B no.1
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• pp.99-104
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• 2002

Existing methods of object tracking use template matching, re-detection of object boundaries or motion information. The template matching method requires very long computation time. The re-detection of object boundaries may produce false edges. The method using motion information shows poor tracking performance in moving camera. In this paper, a robust object tracking algorithm is proposed, using projected motion and histogram intersection. The initial object image is constructed by selecting the regions of interest after image segmentation. From the selected object, the approximate displacement of the object is computed by using 1-dimensional intensity projection in horizontal and vortical direction. Based on the estimated displacement, various template masks are constructed for possible orientations and scales of the object. The best template is selected by using the modified histogram intersection method. The robustness of the proposed tracking algorithm has been verified by experimental results.