Petchmaneelumka, Wandee
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Preferred name
Petchmaneelumka, Wandee
Alternative Name
Petchmaneelumka, W.
Main Affiliation
Email
wandee.pe@kmitl.ac.th
16 results
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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, Position signal detector for linear variable differential transformer(2020-12-01); ; This paper presents the position signal detector for linear variable differential transformer (LVDT) based on RMS-to-DC converter. The proposed detector consists of the differential amplifier, the comparator, the phase detector, the controllable unity-gain inverting/non-inverting amplifier and the RMS-to-DC converter. The proposed technique provides a simple scheme and uses the low cost commercial available devices such as opamp, transistor and digital logic gate. The experimental testing with the commercial LVDT model OP12.5G from Solartron Metrology showing the proposed position signal detector can produce the output voltage corresponding to the measured displacement with satisfactory values and good linearity. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Resistive-Sensor Interfacing Circuit for Remote Measurement Using CFOA(2024-01-01); ; ; Kaewpoonsuk, AnuchaAn alternative approach to implementing an interfacing circuit for resistive sensor-based remote measurement is presented. The proposed technique uses a Current Feedback Operational Amplifier (CFOA) as an active building block to produce an output voltage linearly related to the resistance of the sensor. Moreover, the accuracy of the output voltage is improved by the enhancement of CFOA. In addition, the proposed circuit provides compensation for the effects of lead-wire resistance. The performance of the proposed technique is discussed in detail and confirmed by PSPICE program simulation and experimental implementation. The resistance decade box is used in the experiment. The maximum error on the output voltage of the experimental results is about 0.4234 %. The experimental results show that the proposed technique provides good performance. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Simple LVDT demodulator(2020-10-13); ; A simple technique to realize demodulator for linear variable differential transformer (LVDT) is presented in this paper. The proposed LVDT demodulator is based on sample and hold technique. The proposed scheme consists of peak detector, phase detector, monostable circuit, sample and hold circuit, and controllable unity-gain inverting/noninverting amplifier. The presented technique employs the simple and low-cost devices such as op-amp, and digital logic gate. Experimentation with the commercial LVDT model OP12.5G from Solartron metrology shows that the proposed LVDT demodulator provides the output voltage corresponding to the movement of LVDT core with satisfactory values and good linearity. The maximum error of the proposed demodulator is about 1.5%. In addition, the output magnitude of proposed LVDT demodulator can be adjusted by variable resistor (VR1) without the external circuit requirement. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Capacitive sensor readout circuit based on sample and hold method(2022-04-01); ; This paper presents a capacitive sensor readout circuit using sample and hold method. The proposed readout circuit is used to convert capacitance from sensor to DC (direct current) voltage output. The basic structure of readout circuit consists of the pulse generator circuit, differentiator circuit, amplifier circuit, monostable I circuit, monostable II circuit, and sample and hold circuit. The proposed technique is based on the change of time constant from differentiator circuit corresponding to the measurement capacitance. The sample and hold circuit is used for sampling output voltage from differentiator circuit. The output voltage of the proposed readout circuit is proportional to measurement capacitance. The standard capacitors with different capacitance are used to test the proposed converter performance. Experimental results show that the proposed readout circuit can convert measurement capacitance to output voltage with satisfied values, good linearity and high sensitivity. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Timer-Based Capacitance-to-Voltage Converter(2026-03-01); This article presents the design and analysis of a capacitance-to-voltage converter based on 555-timer Integrated Circuits (ICs) as the core design element. The circuit structure consists of two primary active components: two 555-timer ICs connected in conjunction with a low-pass filter circuit. The first 555-timer IC operates in astable mode to generate a signal that controls the timing of the second IC. The target capacitor or capacitive sensor to be measured is connected to the second 555-timer IC, which operates in monostable mode. The output signal from the second 555-timer IC is then converted into a DC voltage output using a low-pass filter circuit. The circuit was tested using laboratory capacitors in the range of 52.72 pF to 807.61 pF, and the data were analyzed using Microsoft Excel. The results showed excellent agreement with the measurements obtained from the GW INSTEK LCR-819. The maximum uncalibrated error was found to be −3.32% of full scale. After applying linear curve fitting in Excel, the maximum error was reduced to 0.92% of full scale, confirming the effectiveness of the calibration approach. Furthermore, the circuit was applied to measure the moisture content of paddy rice using a cylindrical capacitive sensor within the moisture range of 12.1% to 23.2%. The experimental data were fitted to a derived equation, which was then used to predict rice moisture content, producing results that corresponded closely with those obtained from the KETT PM-450 grain moisture meter. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A Procedure for Precise Determination and Compensation of Lead-Wire Resistance of a Two-Wire Resistance Temperature Detector(2022-06-01); ; 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. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Linear-range extension for linear variable differential transformer using binomial series(2020-01-01); ;