• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.695-696
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.77-78
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• 2009

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.111.2-111
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• 2001

The research focuses on controlling a gap to measure the surface defect in semi-conductor fabrication device. The measurement is available accompanying a near field image gap control. In this article, a pneumatic servo system is adopted for the near field gap control. The advantage of the pneumatic servo system is on the preventing the possibility of contacting the device to the wapper surface, fence arising fatal damage. Furthermore, the air from the pneumatic system blows the some particle on the wapper during controlling. The target gap is less than 20 $\mu$m and the gap should keep same amount while the device moves around the surface. The experiment by the pneumatic servo control system is done by employing a simple PID control, and the tracking performance is remarkably verified. The target gap is set from 10 $\mu$m to 100 $\mu$m ...

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.54-63
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• 2013

In general, multiple hydraulic servo actuators are installed on one control surface of aero-dynamically highly loaded condition aircraft for redundancy management to satisfy flight control safety requirements. If motions of multiple actuators are not synchronized, control surface is deformed from its free stressed state. In result, force fight conditions are generated on each actuator due to restoration reaction force of deformed control surface. In addition, force fight is induced from severe initial rigging tolerance. Force fight condition of multiple actuators affects control accuracies and reduces operational life of actuators and control surface due to fatigue phenomenon. In this study, we designed controller using force feedback to reduce force fight of duplex servo actuation system.

• Transactions of Materials Processing
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• v.20 no.3
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• pp.206-213
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• 2011

A flexible die, which is composed of a number of punches with adjusted heights to form a three-dimensional curved surface, is a crucial part of a flexible forming technology. In this study, the punch and control system of the flexible die were designed. The flexible die is divided into three modules, namely, punch, control and joint, and the corresponding modules were developed. The punch module materializes a three-dimensional forming surface by the control module, which is composed of an AC servo motor set and a linear guide. The joint module is necessary for the sequential motion between the servo motor set and the punch module. A sequential motion algorithm for the AC servo motor set, that uses the data of the punch relative heights, was also proposed. Finally, a flexible stretch forming test was carried out using the presently designed flexible die.

• Journal of Power Electronics
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• v.1 no.1
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• pp.1-8
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• 2001

The elimination of a pole sensor is desirable due to the low-cost requirement, the compactness, and the applied drives. This paper proposes the algorithm for the initial pole-position estimation of a surface permanent magnet linear synchronous motor (PM-LSM), which is carried out under the closed loop control without a pole sensor and is insensitive to the motor parameters. This algorithm is based on the principle that the initial pole position (IPP) is estimated by the trigonometric function of the two reference currents. The effectiveness of the proposed algorithm is confirmed by testing a surface PM-LSM with large disturbance, which result shows that IPP is well estimated within a satisfied moving-distance and a shorter estimation taken-time even if large disturbance such as cogging and friction is existed.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.12
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• pp.1127-1132
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• 2014

Fast tool servo (FTS) is an enabling technology to fabricate various shapes of functional surface geometries in a precise and controllable manner. FTS can be also employed as a straightforward and efficient surface treatment way of making such products more durable. In this work, process characteristics using high-precision FTS-based surface texturing were qualitatively and quantitatively investigated to provide a class of surface design rule. The morphologies of surfaces processed with different conditions were first examined by observing the resultant 2D/3D surface profiles. In addition, the effects of the surface treatment using FTS on hardness and wear properties were characterized and compared to those without treatment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.679-682
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• 2002

Resistance spot welding using air gun has been used for joining the sheet metal in automotive manufacturing process. Although air gun has many advantages, it also has the limitation to control the pressure as a factor to improve weld quality. In this study, we apply servo gun using servo motor to resistance spot welding and find the relationship between welding pressure and welding quality. Trough the experiment to change welding pressure during the welding cycle, we can make it clear that the change of welding pressure is greatly influence on the welding quality. To get in a. using response surface methodology, drew out the optimal welding pressure profile for welding quality progresses. We made an optimal profile of welding pressure which improves welding quality using response surface methodology.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.137-139
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• 2007

In optical disk drives, a conventional control method in the presence of surface defect is holding the previous tracking control command. It is known that the method has a long settling time. This paper proposes a new control method which reduces the settling time. An optical head generally has coupled dynamics between focusing and tracking servo system. We present how to compensate the coupled dynamics so that reduced settling time is achieved. It is verified by experiments that the proposed method brings an improved performance in the presence of surface defect as well as in the normal operating condition.

• Journal of Mechanical Science and Technology
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• v.16 no.12
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• pp.1664-1672
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• 2002

Gantry mechanisms have been widely used for precision manufacturing and material handling in electronics, nuclear, and automotive industries. Dual-drive servo mechanism is a way to increase control bandwidth, in which two primary axes aligned in parallel are synchronously driven by identical servo motors. With this mechanism, a flexible coupling (compliance mechanism) is often introduced in order to avoid the damage by the servo mismatch between the primary drives located at each side of gantry. This paper describes the design guidelines of the dual-drive servo mechanism with focus on its dynamic characteristics and control ramifications. That is, the effect on the system bandwidth which is critical on the system performance, the errors and torques exerted on guide ways in case of servo mismatch, the vibration characteristics concerned with dynamic error and settling time, and the driving force required at each axis for control are thoroughly investigated.