Rerkratn, Apinai
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Rerkratn, Apinai
Alternative Name
Rerkratn, A.
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Email
apinai.re@kmitl.ac.th
67 results
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Item type:Publication, A simple amplitude detector-based demodulator for resolver converters(2010-12-01); 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. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Linear Variable Differential Transformer Signal Conditioning Circuit Based on Phase-Locked LoopThe purpose of this paper is to propose a novel technique for extracting the position signal from an inductive displacement transducer named a linear variable differential transformer (LVDT). In general, the movement of the LVDT core causes its primary inductance change in linear form. The primary winding of the LVDT is used as a time-dependent element for the triangular and square wave generator, which can be called self-oscillation, to generate frequency. The advantage of the proposed technique is that it can measure the displacement using the LVDT without an external oscillator. The change in primary inductance causes the frequency deviation generated by the oscillator. The deviated frequency is captured and converted into a voltage signal using the principle of the phase-locked loop. All the components used in this study are commercially available. The merits of this proposed technique are simple configuration, small size, and low cost. Moreover, the operating range of the LVDT can be extended without the limitation of the nonlinear transfer characteristic. The performance of the proposed technique is discussed in detail and confirmed by experimental implementation. Experimental results show that the maximum error from the proposed technique is about 0.42% and the operating range of the LVDT can be extended to more than 200%. It can be seen that the proposed technique is suitable for embedded measurement in small or micro robots. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Temperature Compensation for Transformer-type TransducerA novel technique to compensate the temperature effect of a transformer-type transducer is proposed in this paper. The effect of the ambient temperature on the transformer-type transducer is investigated from a primary-winding current. The advantage of the proposed technique is that the temperature effect is compensated without requiring a temperature sensor, making it suitable for applications in robotic and automation systems operated in harsh environments. The primary-winding current of the transducer is generated using a second-generation current conveyor (CCII). The excitation signal of the transformer-type transducer is driven by the CCII and the current flowing through the primary winding is transferred to an output signal of the CCII. The deviation of the primary-winding current due to the temperature effect is evaluated from the output signal of the CCII. The temperature effect on the transducer is manipulated by a closed-loop principle using a subtract-and-sum action instead of a traditional proportional-plusintegral action to eliminate the deviation of the primary-winding current. Therefore, the temperature effect on the transducer is compensated. A linear variable differential transformer (LVDT) is used to demonstrate the proposed technique, whose performance is discussed in detail and confirmed experimentally. All devices used in this experiment are commercially available. Experimental results show that the measured error of the output signal from the LVDT at 70 C can be reduced from 6.2% without temperature compensation to 0.06% by using the proposed technique, which has the advantages of a low cost, simple configuration, and high performance. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Wireless Carbon Monoxide Level Control and Monitoring SystemThis paper proposes an online carbon monoxide control and monitoring system. The proposed system comprises an MQ-7 CO gas sensor module, a DHT11 digital temperature and humidity sensor module, an ESP8266 module, and a Relay Module. The ThingSpeak platform is used to create HMI for online monitoring of CO level, temperature, humidity, and status of the ventilation fan. This proposed system can measure CO and monitor all parameters of measurement data, alert users when CO values exceed the set value. In addition, the measured CO values are used to control the ventilation system operation (ON or OFF) to maintain the CO at a non-harmful level. The experiment testing and results with three conditions show that the proposed system can measure and monitor CO level, temperature, and humidity online with satisfying values. The ventilation fan can operate with function as a design procedure and maintain CO at a non-harmful level. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Four-quadrant analogue multiplier using operational amplifier(2011-04-01); A method to realise a four-quadrant analogue multiplier using general-purpose operational amplifiers (opamps) as only the active elements is described in this article. The realisation method is based on the quarter-square technique, which utilises the inherent square-law characteristic of class AB output stage of the opamp. The multiplier can be achieved from the proposed structure with using either bipolar or complementary metal-oxide-semiconductor (CMOS) opamps. The operation principle of the proposed multiplier has been confirmed by PSPICE analogue simulation program. Simulation results reveal that the principle of proposed scheme provides an adequate performance for a fourquadrant analogue multiplier. Experimental implementations of the proposed multiplier using bipolar and CMOS opamps are performed to verify the circuit performances. Measured results of the experimental proposed schemes based on the use of bipolar and CMOS opamps with supply voltage ±2.4 V show the worst-case relative errors of 0.32% and 0.47%, and the total harmonic distortions of 0.47% and 0.98%, respectively. © 2011 Taylor & Francis. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Internet-based conductivity measurement system with self-temperature compensation(2019-07-01); Kaewpoonsuk, AnuchaAn Internet-based conductivity measurement system with self-temperature compensation is presented in the paper. In order to get a simple and portable measurement system, a readout circuit in analog part is designed using only two operational amplifiers (opamps) connected with basic electronic components and energized using single supply voltage. An excitation voltage generated by the AD9833 module is applied to a conductivity sensor. The measured output DC voltages are found to be directly proportional to the conductivity of the solution. The NodeMCU ESP8266 WiFi dev board is used to determine the conductivity and measure the temperature whose effect on the conductivity is compensated. The measured results are sent to display on a smartphone by Blynk app. The conductivity measured by the proposed system is in good agreement with that due to the standard EC meter. A maximum error of measuring the conductivity at different temperatures of solution is 4.79% of full scale. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Digital fieldbus-Analog system integration for revamping projectsThis paper presents a system integration of modern digital fieldbus and traditional analog devices for revamping projects. Using temperature transmitter with Foundation Fieldbus technology and power regulator with 4-20 mA control input for temperature control based on a PID instruction of programmable logic controller (PLC) is examined as an illustrative case study. A portable plant model was designed and implemented for real hands-on training. In addition, basic network and device configurations as well as ladder logic program and graphical user interface creations are discussed. Experimental results of temperature control in the range of 40-60 °C verifying the proposed concept are also included. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Simple and low-cost readout circuit for differential resistive sensors(2018-09-01); Kaewpoonsuk, AnuchaIn this paper, a simple and low-cost readout circuit for differential resistive sensors is presented. The realization method is based on the relaxation oscillation technique, which utilizes the operational amplifiers (op-amps) with a single supply voltage. The oscillating output Duty-Cycle is proportional to the difference of two sensing resistances. In comparison with the traditional voltage divider circuit or the Wheatstone bridge circuit or the previously reported readout circuit based on CCIIs, the proposed circuit can be interfaced with microcontroller without using an analog-to-digital converter. Theoretical predictions are supported by the PSPICE simulation results and the experimental data. In applying a slide potentiometer with changes of slider positions of ±15 mm, it is found that the maximum error of the proposed circuit is approximately-2.90% of full-scale. Copyright © 2018 Praise Worthy Prize S.r.l.-All rights reserved. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Real-time seafood quality monitoring system using interdigital sensor(2020-01-01); Many studies showed that seafood consumption contains many health benefits. However, the spoilage of such products causes the vast economic loss each year. An effective monitoring and inspection system for quality is required during the storage of these products. Most existing methods for such inspection require laboratory tests. In this study, the interdigital sensor was developed and applied to inspect the spoilage of seafood. The sensor was designed to monitor the change of impedance during spoilage progression of seafood. The result revealed that impedance of liquid decreased overtime. This coincides with the fact that spoilage of seafood generates ammonium ion which causes decrease in the impedance of the liquid. The designed sensor was then merged with the proposed system which consists of a sine wave circuit, a voltage control current source circuit, an interdigital sensor, an amplifier circuit, a rectifier circuit, a low-pass filter circuit, a comparator circuit and a display circuit. These circuits adjusted the signals received from the sensor to be proper to the application. The experiment was designed to have conditions similar to the real-world situation of how seafood is stored. The experimental results showed that the proposed system effectively indicated the change of seafood quality. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Non-destructive Fertility Detection of Multiple Chicken Eggs Using Image Processing and Convolutional Neural Network(2020-07-30)