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Journal ArticleDOI

Digital Converter for a Contactless Displacement Sensor

TL;DR: A novel signal-conditioning circuit is developed such that the digital output is independent of the coupling capacitor that arises between the floating wiper and the resistive element, thus eliminating the effect of any jitter that may arise in the movement of the wiper.
Abstract: This paper presents a novel digital converter for a contactless displacement transducer. The sensor part of the proposed transducer employs a floating (contactless) wiper that moves over a resistive element. A novel signal-conditioning circuit presented here operates on the contactless resistive potentiometer element and provides a digital output that linearly varies with the position of the wiper. The signal-conditioning circuit is developed such that the digital output is independent of the coupling capacitor that arises between the floating wiper and the resistive element, thus eliminating the effect of any jitter that may arise in the movement of the wiper. Results from a prototype circuit built and tested using a prototype sensor establish the efficacy of the proffered scheme.
Citations
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Journal ArticleDOI
TL;DR: A sigma-delta-type digital converter suitable for a resistive-potentiometer-type displacement sensor with a floating slide is presented here and results obtained from simulation studies, emulation studies, and experimentation conducted on a prototype sensor establish the efficacy of the proffered scheme.
Abstract: A sigma–delta-type digital converter (SDC) suitable for a resistive-potentiometer-type displacement sensor with a floating slide is presented here. The delta modulator in a conventional SDC is suitably altered to incorporate, as its integral part, a resistive-potentiometer-type displacement sensor with a floating slide. The operation of the 1-b quantizer in the SDC is modified such that the digital output of the SDC directly indicates the displacement being sensed. The results obtained from simulation studies, emulation studies, and experimentation conducted on a prototype sensor establish the efficacy of the proffered scheme.

12 citations


Cites background from "Digital Converter for a Contactless..."

  • ...A dual slope ADC-based scheme presented earlier for resistive-potentiometer-type displacement sensors can provide only a few conversions per second [7]....

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Journal ArticleDOI
TL;DR: This paper proposes a novel method for demodulating low-frequency amplitude-modulated (AM) signals provided by sensors using a digital timer that carries out the demodulation and digitization simultaneously, without requiring a rectifier, a mixer, a low-pass filter, or an analog-to-digital converter.
Abstract: This paper proposes a novel method for demodulating low-frequency amplitude-modulated (AM) signals provided by sensors. The method relies on a digital timer that carries out the demodulation and digitization simultaneously, without requiring a rectifier, a mixer, a low-pass filter, or an analog-to-digital converter. This timer-based demodulator extracts the amplitude of the AM signal by measuring the period of a reference signal that is altered by the AM signal itself. The period measurement undergoes a deviation that carries information about the amplitude of the AM signal. The feasibility and also the limitations, such as the nonlinearity and aliasing effects, of this novel demodulator are proved theoretically and experimentally. The concept is also applied to measure an inductive displacement sensor in a range of ±30 mm. A nonlinearity error of 0.5% full-scale span and a resolution of 9 bits are achieved for an overall measuring time of 100 ms.

12 citations


Cites background from "Digital Converter for a Contactless..."

  • ...happens in the circuits for resistive displacement sensors recently suggested in [35] and [36] with a conversion time...

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Proceedings ArticleDOI
23 May 2016
TL;DR: A novel, floating wiper, inductive voltage divider (IVD) type displacement transducer is presented here, which provides an output that is proportional to the displacement (can be linear or angular) of the wiper.
Abstract: A novel, floating wiper, inductive voltage divider (IVD) type displacement transducer is presented here. A self balancing signal conditioning circuit, proposed herein, operates on an IVD with a floating wiper and provides an output that is proportional to the displacement (can be linear or angular) of the wiper. The output is made independent of the coupling capacitor that would arise due to the air gap between the inductive element and the floating wiper. Thus the output of the proffered transducer is unaffected by any jitter that may occur and alter the distance between the wiper and the IVD. The workability of the proposed transducer is extensively verified through simulation studies.

5 citations

Proceedings ArticleDOI
01 May 2017
TL;DR: A non-contact inductive voltage divider (IVD) type displacement transducer that directly provides a digital output proportional to the displacement of the non- contact (floating) wiper is presented here.
Abstract: A non-contact inductive voltage divider (IVD) type displacement transducer that directly provides a digital output proportional to the displacement of the non-contact (floating) wiper is presented here. The floating wiper IVD becomes an integral part of a suitably modified dual slope type digital converter (DSDC) and the logic of conversion ensures that the digital output of the DSDC is not affected by the changes in the distance between the floating wiper and the inductive element. Simulation and emulation studies have been carried out to establish the feasibility and functionality of the proposed method. Experimentation on a prototype non-contact inductive angular displacement sensor built in the laboratory further corroborates the efficacy of the proffered technique.

2 citations


Cites methods from "Digital Converter for a Contactless..."

  • ...A dual slope converter proposed earlier for the resistive potentiometric type displacement sensor with a floating wiper is not suited for the IVD type sensor owing to the fact that dc sources are employed for powering the sensing element [7]....

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Proceedings ArticleDOI
01 Oct 2019
TL;DR: A novel signal conditioning circuit that operates on a floating wiper resistive displacement sensor and provides a digital output proportional to the displacement of the wiper is presented here.
Abstract: A novel signal conditioning circuit that operates on a floating wiper resistive displacement sensor and provides a digital output proportional to the displacement of the wiper is presented here. Floating wiper resistive displacement sensors possess long operational life due to reduced wear and tear as the wiper does not rub against the resistive element. However, the air gap between the floating wiper and the resistance introduces a coupling capacitance whose value varies as the wiper moves, making it difficult to obtain an output proportional to the displacement of the wiper. The successive approximation logic-based method presented here, operates on a floating wiper resistive displacement sensor and provides a digital output that is linear to the displacement of the wiper. More importantly the output is independent of the value of coupling capacitance. The efficacy of the scheme has been established through simulation studies, the results of which are also presented here.

2 citations


Additional excerpts

  • ...The scheme proposed in [10] provides a digital output proportional to the displacement of the floating wiper but is based on the dual slope analogue to digital conversion (ADC) principle and hence possesses very low conversion (sampling) rate....

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References
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Journal ArticleDOI
TL;DR: The autoadaptative signal processing presented in this paper has been computed in order to improve the accuracy of an interferometric displacement sensor.
Abstract: A semiconductor laser subject to moderate optical feedback has been used to design an interferometric displacement sensor. The autoadaptative signal processing presented in this paper has been computed in order to improve the accuracy of such a sensor. This setup has been successfully tested for both harmonic and aleatory displacements of a remote piezoelectric actuator with a maximum accuracy of 40 nm

190 citations

Journal ArticleDOI
TL;DR: A novel circuit to directly connect differential resistive sensors to microcontrollers without using either a signal conditioner or an analog-to-digital converter (ADC) in the signal path is introduced.
Abstract: This paper is a continuation of a previous work with regard to the direct connection of differential sensors to microcontrollers without using intermediate electronics between them. This paper focuses on the measurement of differential capacitive sensors, whereas the previous work dealt with the resistive counterparts. The proposed circuit is analyzed, and the main limitation seems to be the fact that the magnitude of the input parasitic capacitances of the microcontroller is similar to or even higher than the sensor capacitances. Methods to overcome this limitation are proposed, particularly when measuring low-value differential capacitive sensors such as microelectromechanical system (MEMS) sensors. Experimental tests of the circuit have been carried out by measuring a commercial capacitive accelerometer working as a tilt sensor. Although such a sensor has a low value (1.5 pF) and low sensitivity (0.105 pF/g), the measurement has shown a nonlinearity error of 1% full-scale span (FSS), which is a remarkable value considering the simplicity of the circuit.

91 citations


"Digital Converter for a Contactless..." refers background in this paper

  • ...Similarly, a direct microcontroller interface scheme of resistive sensors is proposed and given in [18]....

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Journal ArticleDOI
TL;DR: In this article, an absolute capacitive angular-position sensor with a contactless rotor is presented, which is mainly composed of three parts: the capacitive sensing element, a signal processor, and a microcontroller.
Abstract: This paper presents an absolute capacitive angular-position sensor with a contactless rotor. The sensor is mainly composed of three parts: the capacitive sensing element, a signal processor, and a microcontroller. The electrically floating rotor can be either conductive or dielectric. For the dielectric material, we chose plastic, and for the conductive rotor, we chose aluminum. The sensing element has a redundant structure, which reduces mechanical nonidealities. The signal processor has a multicapacitance input and a single output, which is a period-modulated square-wave voltage. The microcontroller acquires output data from the processor and sends them to a PC, which calculates the rotor position. Theoretical analysis, supported by experimental results, show that the sensitivity to mechanical nonidealities of the sensing element is higher in the case of a conductive rotor. The resolution of the capacitive angular-position sensor over the full range (360/spl deg/) was better than 1". The measured nonlinearity was /spl plusmn/ 100" and /spl plusmn/ 300" for the dielectric and the conductive rotor, respectively.

75 citations


"Digital Converter for a Contactless..." refers methods in this paper

  • ...To overcome this problem, contactless displacement transducers have been developed and are preferred for applications such as automobiles, robotics, and manufacturing plants [4]–[6]....

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  • ...Several types of contactless displacement transducers based on: 1) Hall effect sensor element [4]; 2) inductive sensing element [5]; and 3) capacitive sensor element [6] have been developed....

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Journal ArticleDOI
01 Jan 1995
TL;DR: In this paper, a very linear oscillator is used in the processing circuit to convert the position quantity to a period-modulated signal which can be read out directly by a microcontroller.
Abstract: A novel smart resistive-capacitive angular position sensor is presented. The main advantages of this low-cost system are its simplicity, high stability and high reliability. A very linear oscillator is used in the processing circuit to convert the position quantity to a period-modulated signal which can be read out directly by a microcontroller. The system does not need an A/D converter. The nonlinearity of the smart angular position sensor system is less than /spl plusmn/0.3% (/spl plusmn/0.9/spl deg/) over the range of 270. >

56 citations


"Digital Converter for a Contactless..." refers background or methods in this paper

  • ...Compared with the above contactless displacement transducers, a contactless resistive potentiometric-type displacement transducer [15] will not only possess long life and contact free operation but also bring in all the advantages of a resistive potentiometric displacement transducer, such as: 1) simplicity in design; 2) easy operation; 3) high linearity over a wide range of operation; and 4) low cost....

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  • ...better than the accuracy of the method reported in [15]....

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  • ...The power consumption of the scheme in [15]...

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  • ...5 mJ (225 × 10−3 × 100 × 10−3) required for the scheme in [15]....

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  • ...In a contactless resistive–capacitive displacement transducer [15], the problematic part of a potentiometrictype displacement transducer, namely, the spring loaded...

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Proceedings ArticleDOI
01 Oct 2009
TL;DR: The absence of complex digital signal treatment makes this technique a natural method for measuring the magnetic field direction and therefore for designing an angular position sensor using Hall probes.
Abstract: We present a technique for contactless angular position sensing that allows low power consumption while keeping dynamic properties comparable to existing sensors. The technique essentially consists in combining a recently developed sensing element, the so-called Circular Vertical Hall Device, with a simple and robust signal treatment based on phase detection. Because of its low startup time, this circuit is specially suited for pulsed mode operation, which enables to further decrease the power consumption. More generally, the absence of complex digital signal treatment makes this technique a natural method for measuring the magnetic field direction and therefore for designing an angular position sensor using Hall probes.

47 citations


"Digital Converter for a Contactless..." refers methods in this paper

  • ...To overcome this problem, contactless displacement transducers have been developed and are preferred for applications such as automobiles, robotics, and manufacturing plants [4]–[6]....

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  • ...Several types of contactless displacement transducers based on: 1) Hall effect sensor element [4]; 2) inductive sensing element [5]; and 3) capacitive sensor element [6] have been developed....

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