A linear, millimetre displacement-to-frequency transducer.
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Experimental results confirm that a displacement of 0-100 mm is converted into a frequency range of 0-100 kHz, with a normalised fidelity factor of 99.91%, and a worst-case nonlinearity of less than 0.08%.Tests using laboratory standards show that a displacement of 10 mm is transduced with an accuracy of ± 0.6%, and a standard deviation of 530 Hz.Estimates included in the paper show that the transducer could cost less than 1% of existing systems for millimeter displacement measurement.
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PubMed Central - PubMed
Affiliation: Department of Electrical Engineering, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa. ageejt@tut.ac.za
ABSTRACT
The paper presents a novel linear, high-fidelity millimetre displacement-to-frequency transducer, based on the resistive conversion of displacement into a proportional voltage, and then frequency. The derivation of the nonlinearity, fidelity and sensitivity of the transducer is presented. Experimental results confirm that a displacement of 0-100 mm is converted into a frequency range of 0-100 kHz, with a normalised fidelity factor of 99.91%, and a worst-case nonlinearity of less than 0.08%. Tests using laboratory standards show that a displacement of 10 mm is transduced with an accuracy of ± 0.6%, and a standard deviation of 530 Hz. Estimates included in the paper show that the transducer could cost less than 1% of existing systems for millimeter displacement measurement. No MeSH data available. |
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Mentions: The simulated fidelity results presented in Figure 4 shows that, the conditioning of the sensor signal by the primary amplifier was undertaken with at least 99.91% fidelity. Figure 5 shows that the introduction of the conditioning circuit slightly reduced the normalized input sensitivity to a value less than unity (0.988). As shown in Figure 6, the choice of K = 0.0056 has reduced the worst case nonlinearity to 0.18% < 4%, as typically allowed in instrumentation [9]. The experimental measurements, confirmed the linearity between the displacement and the displacement-dependent voltage ETH as in Figure 8. Figure 9 shows that, the connection of the voltage amplifier has introduced nearly 0.22% nonlinearity (obtained from the linear correlation coefficient); also slightly reducing the normalized sensitivity from a value of unity to 0.9978. Experimental results of the overall displacement-to-frequency conversion process are shown in Figure 10. It is evident there-from, that the millimetre-to-frequency converter has an overall linearity to 99.92%, or a nonlinearity of 0.08%. Results from the precision analysis of the displacement-to-frequency transducer are shown in Figures 11 and 12. It is evident from these, that for a 10 mm displacement, a mean measurement of 10,062 Hz (for 100,000 Hz) was obtained, giving a transducer accuracy of ±0.62%; the standard deviation of the measurements was 530 Hz. |
View Article: PubMed Central - PubMed
Affiliation: Department of Electrical Engineering, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa. ageejt@tut.ac.za
No MeSH data available.