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    A simple amplitude detector-based demodulator for resolver converters
    (2010-12-01)
    Kaewpoonsuk, Anucha
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    Katman, Ratchanoo
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    Kamsri, Thawatchai
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    This paper presents a simple method based on sinusoidal-amplitude detector for realizing the resolver-signal demodulator. The proposed demodulator consists of two full-wave rectifiers, two ±unity-gain amplifiers, and two sinusoidal-amplitude detectors with control switches. Two output voltages are proportional to sine and cosine envelopes of resolver-shaft angle without low-pass filter. Experimental results demonstrating characteristic of the proposed circuit are included. ©ICROS.
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    Item type:Publication,
    A Procedure for Precise Determination and Compensation of Lead-Wire Resistance of a Two-Wire Resistance Temperature Detector
    (2022-06-01) ;
    Prombut, Supatsorn
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    Kamsri, Thawatchai
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    ;
    A procedure for the precise determination and compensation of the lead-wire resistance of a resistance transducer is presented. The proposed technique is suitable for a two-wire resistance transducer, especially the resistance temperature detector (RTD). The proposed procedure provides a technique to compensate for the lead-wire resistance using a three-level pulse signal to excite the RTD via the long lead wire. In addition, the variation in the lead-wire resistance disturbed by the change in the ambient temperature can also be compensated by using the proposed technique. The determination of the lead-wire resistance from the proposed procedure requires a simple computation method performed by a digital signal processing unit. Therefore, the calculation of the RTD resistance and the lead-wire resistance can be achieved without the requirement of a high-speed digital signal processing unit. The proposed procedure is implemented on two platforms to confirm its effectiveness: the LabVIEW computer program and the microcontroller board. Experimental results show that the RTD resistance was accurately acquired, where the measured temperature varied from 0<sup>◦</sup>C to 300<sup>◦</sup>C and the lead-wire resistance varied from 0.2 Ω to 20 Ω, corresponding to the length of the 26 American wire gauge (AWG) lead wire from 1.5 m to 150 m. The average power dissipation to the RTD was very low and the self-heating of the RTD was minimized. The measurement error of the RTD resistance observed for pt100 was within ±0.98 Ω or ±0.27<sup>◦</sup>C when the lead wire of 30 m was placed in an environment with the ambient temperature varying from 30<sup>◦</sup>C to 70<sup>◦</sup>C. It is evident that the proposed procedure provided a performance that agreed with the theoretical expectation.
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    Item type:Publication,
    An accurate CCII-based voltage controlled current source
    (2008-12-01)
    Kaewpoonsuk, Anucha
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    Riewruja, Vancliai
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    Kamsri, Thawatchai
    In this paper, a voltage controlled current source (VCCS) providing low distortion in output signal and wide output current range is introducted. In order to obtain the high accuracy, the proposed technique employs the designed scheme to connect in feedback loop of the basic VCCS based on second generation current conveyor (CCII). This scheme consists of instrumentation and differential amplifiers and one resistor. The performances of the proposed circuit were studied through the use of PSPICE simulation program. Simulation results are agreed with the expected values.
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    Item type:Publication,
    System development for orange surface defect detection using image processing
    (2015-01-01) ; ;
    Kaewpoonsuk, Anucha
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    Kamsri, Thawatchai
    This paper presents system development for orange surface defect detection using image processing. The proposed system consists of conveyer belt, Ultraviolet (UV) lamp, CCD Camera, electronic circuits, interface card and computer. K-means clustering and thresholding techniques are used for inspection of surface defect. The image segments are employed to calculate area of surface defect. The experimental results show that the proposed system can be detection of surface defect.