• Journal of the Korean Society for Precision Engineering
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• v.25 no.8
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• pp.29-36
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• 2008

An optical rotary encoder is easy to implement for automation system applications. In particular, the output of the encoder has a digital form pulse, which is also easy to be connected to a popular digital controller. By using an incremental encoder and a counting device, it is easy to measure angular displacement, as the number of the output pulses is proportional to the rotational displacement. This method can only detect the angular placement once a pulse signal comes out of the encoder. The angular displacement detection period is strongly subject to the change of the angular displacement in case of ultimate low velocity range. They have ultimate long detection period or cannot even detect angular displacement at near zero velocity. This paper proposes an algorithm for detecting angular displacement by using a dual encoder system with two encoders of normal resolution. The angular displacement detecting algorithm is able to keep detection period moderately at near zero velocity and even detect constant angular displacement within nominal period. It is useful for motion control applications in case of changing rotational direction at which there occurs zero velocity. In this paper, various experimental results are shown for the angular displacement detection algorithm.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.177-181
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• 1997

In the speed control system of motors using the low resolution rotary encoder, the period of encoder pulse becomes longer than the sampling time for speed control in the range of very low speed. Therefore, it is difficult to obtain accurate speed information. In this paper, the speed estimating method at the very low speed region using reduced order torque observer, which has been widely used, is examined. The results of simulation show that the characteristics of the speed control at the very low speed region is improved by using the reduced order torque observer.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.1
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• pp.132-136
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• 2008

Axis of rotation error on rotary system are significant; such as the spindle radial error motion of a aligner, wire bonder and inspector machine which results in the poor state of manufactured goods. In this paper, the simple stage which consists of one PZT actuator and rotary encoder, is analyzed and measured by high resolution capacitance type displacement sensor. As the result of experiment, the paper discusses several issues that must be considered when designing rotary stage driven by PZT.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.1
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• pp.87-94
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• 2005

This paper is about the compensation of phase angle error and amplitude difference in stationary 2 pole coordinates by the installation variation of sensor at low cost high resolution digital hybrid encoder. To solve the problem of amplitude difference at the existing hybrid encoder, we normalized the relative magnitude of the two analog signals. and also to solve the problem of installation variation when installed the sensor, we rotate the stationary 2 pole coordinates to compensate the location error of sensor. and we used and tested the QEP function and A/D port in DSP(TMS320F2812) to verify the mentioned proposed method.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.7
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• pp.94-100
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• 2010

This paper describes the design and evaluation procedure of an ultra-precision rotary table for freeform generating machined tools. Design of the thrust and journal hydrostatic bearings and experimental evaluation of the table were performed. To get the compact size and less lost motion direct drive servomotor with ultra precision encoder. From the considered design, following performance were confirmed by experiment. The total stiffness of the prototype rotary table was 483.6 $N/{\mu}m$ and 97.6 $N/{\mu}m$ for axial and radial direction, respectively. Rotational accuracy of the table was investigated by capacitive sensor and reversal measurement technique, and 0.10 ${\mu}m$ radial direction and 0.05 ${\mu}m$ axial direction of the rotational accuracy were confirmed. The micro resolution of the table was also investigated with displacement of capacitive sensor, and $0.5/10000^{\circ}$ of micro resolution was confirmed. Index accuracy of the table was evaluated by the autocollimator and polygon mirror, and the $\pm0.39$ arcsec accuracy and $\pm0.16$ arcsec repeatability of the table were confirmed. Those are under the general requirements of ultra precision rotary tables for freeform generating machined tools.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.269-274
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• 2013

To proportionally control the electronic valve position of the actuator, we designed and fabricated PCU, CPT, and rotary absolute optical encoder for the detection of absolute angular position in the actuator. We also designed and constructed the test system by using DAQ hardware and Labview. We designed PCU to convert 1-5 V, 0-5 V, 0-10 V, 2-10 V voltage signals and 4-20 mA current signals to the voltage signals in the common 0.5-2.5 V range. We designed CPT to output 4-20 mA current signals corresponding to the valve positions based on the PWM signal input from the MCU. We also designed 20 bit optical encoder by using infrared LED and infrared transistor and made the serial communication with the main board possible. When we tested PCU and CPT with DAQ hardware and Labview software, they operated correctly with the small errors within ${\pm}0.003$ V and ${\pm}0.01$ mA, respectively, showing that our actuator has the excellent performance to employ as the industrial proportional-valve-actuator. The resolution of the encoder was $11.25^{\circ}$ and the maximum revolution to detect was 32,768.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.2 s.233
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• pp.311-317
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• 2005

NC controller parameters are fixed when the controller is combined with a machine. However, the characteristics of controller could be changed as it has being used by the machine or other environmental conditions. Ultimately, it results in tool positioning accuracy changing. The loading torque in servo motor also influences on the positioning accuracy. This study focus on a measuring and analysing method for verifying the angular positioning accuracy of NC servo motor. We used a high resolution A/D converter for acquiring analogue signal of rotary encoder in servo motor. Generating tool path by the combination of axial movements (X,Y,Z) is compared with the encoder signals with the servo motor torque. The current variation signal is also read from the servo motor power using a hall sensor and converted to the motor torque. The method of analysing proposed in this study will be used for determining the gains (tuning) of parameter in NC controller, when the controller is set up at a machine initially or the controller condition is changed during the work.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.65-69
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• 1997

Generally, we often use a speed sensor based on a rotary encoder and we can obtain a speed information by counting the increased or decreased number of encoder pulses in a sampling period. However, these speed measurement systems do not inherently produce a true, instantaneous speed information and them the speed ripple is generated by speed measurement errors. In order to overcome this problem, speed observer is used for the accurate speed measurement and improvement of speed ripple for Permanent Magnet Synchronous Motor (PMSM) in this paper. Speed observer estimates the instantaneous speed at each sampling instant. This estimated speed signal is then used as the speed feedback signal for the speed loop control. The proposed speed observer system is proved simulation using SABER simulation S/W.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.4
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• pp.16-20
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• 2010

The dynamic characteristics of flight sensors is obtained by a simple method that deploys a pendulum with a rotary encoder. The encoder output is used with kinematic relations to derive reference signals for various flight sensors, including position, velocity, attitude, and angular rate sensors as well as accelerometer and magnetic sensors. A time delay of 0.4 seconds is found in the position output of the flight sensor under investigation. A logic to compensate for the time delay using a velocity information is proposed and validated in flight tests.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.4
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• pp.21-27
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• 2004

In this paper, data acquisition and analysis of a measuring machine for marine engine's cams are discussed. A rotary encoder and linear scale of the machine to measure angular and linear displacement, respectively, are interfaced to the PC via an encoder board with 2 channels. The design and measuring data are interpolated by cubic spline curves to compute the precision error which is defined by the maximum and minimum distances between two curves. The minimum zone fit of ISO is employed to evaluate the geometric deviation. The developed system takes only 5 minutes to measure and analyze the precision error while the CMM takes over I hours even with a skilled operator.