• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.461-465
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• 1996

In servo systems such as the computer hard disk, surface mountiong device and robot manipulators, the high precision and high speed are increasingly demanding. In these examples, the repeatable errors exist and the repetitive controller removes these errors effectively by adding signals calculated from the previous cycle errors to the existing feedback controller. The experimental results of the position tracking control and contact force control show that the repetitive control effectively improves the precision of mechanical servo systems.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.9
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• pp.909-915
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• 2009

This work is to develop a vision system for high precision alignment between upper and lower plates required at the imprinting process of the large LCD flat panel. We compose a gantry-stage that has highly repeated accuracy for high precision alignment and achieves analysis about thermal transformations of stage itself. Position error in the stage is corrected by feedback control from the analysis. This system can confirm alignment mark of upper and lower plates by using two cameras at a time for the alignment of two plates. Pattern matching that uses geometric feature is proposed to consider the recognition problem for alignment mark of two plates. It is algorithm to correct central point and angle for the alignment from the recognized mark of upper and lower plates based on the special characteristics. At the alignment process, revision for error position is performed through Look and Move techniques.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.9-15
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• 1999

A piezoelectric actuator is widely used in precision positioning applications due to its excellent positioning resolution. However, the piezoelectric actuator lacks in repeatability because of its inherently high hysteresis characteristic between voltage and displacement. In this paper, a controller is proposed to compensate the hysteresis nonlinearity. The controller is composed of a PID and a neural network part in parallel manner. The output of the PID controller is used to teach the neural network controller by the unsupervised learning method. In addition, the PID controller stabilizes the piezoelectric actuator in the beginning of the learning process, when the neural network controller is not learned. However, after the learning process the piezoelectric actuator is mainly controlled by the neural netwok controller. In this paper, the excellent tracking performance of the proposed controller was verified by experiments and was compared with the classical PID controller.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.4
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• pp.271-275
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• 2016

For machining systems like the motor driven linear stage which have high precision positioning with a long stroke, it is necessary to examine the repeatability of the reference position decision. Though piezo (PZT) actuator driven linear stages have high precision feed drivers and a short stroke, they have some limitations for reference position decisions if they have not been equipped with an accurate home sensor. This study was performed to examine the repeatability for home position decision of a EE-SX671 photo sensor as a home switch by using piezo actuator driven linear stages and capacitance probe.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.458-461
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• 2002

This study presents development of a machine for shrink wrapping of cans or drink bottles with thermoplastic films. The accurate position-control, the safety factor of chains, the reduction-ratio of the chain and gear, the appropriate heating temperature for banding vinyl are discussed for the optimum shrink wrapping M/C design.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.813-816
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• 1999

In this paper is Proposed a VSC(variable structure controller) for a high-speed and high-precision position control of a XY Table, which is based on the PI type reaching mode. Also the comparative study between the proposed method and the conventional PID controller is presented as well. Designed and tuned under repeated experiments, the proposed method showed a better reasonable performance than PID controller in the aspect of tracking error.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.485-486
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• 2008

• Journal of the Korean Society for Precision Engineering
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• v.18 no.12
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• pp.30-46
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• 2001

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.590-593
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• 2001

In this paper we describe the 6-axes robot's position determination using a stereo vision and an image based control method. When use a stereo vision, it need a additional time to compare with mono vision system. So to reduce the time required, we use the stereo vision not image Jacobian matrix estimation but depth estimation. Image based control is not needed the high-precision of camera calibration by using a image Jacobian. The experiment is executed as devide by two part. The first is depth estimation by stereo vision and the second is robot manipulator's positioning.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.97-100
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• 1997

A new control method for the robust position control of a brushless DC(BLDC) motor using the asymptotically stable adaptive load torque observer is presented. A precision position control is obtained for the BLDC motor system approximately linearized using the field-orientation method. And the application of the load torque observer is published in [1] using fixed gain. However, the flux linkage is not exactly known for a load torque observer. Therefore, a model reference adaptive observer is considered to overcome the problem of the unknown parameter in this paper. And stability analysis is carried out using Liapunov stability theorem. As a result, asymptotically stable observer gain can be obtained without affecting the overall system response. The load disturbance detected by the asymptotically stable adaptive observer is compensated by feedforwarding the equivalent current having the fast response.