Inductive sensor

About: Inductive sensor is a research topic. Over the lifetime, 2282 publications have been published within this topic receiving 21984 citations.

Design of planar capacitive type sensor for “water content” monitoring in a production line

Abstract: Capacitive type sensors for the measurement of water content of various materials exhibit the serious handicap of the sensitivity dependence on the spacing between sensor and material. The results of theoretical investigation show that is possible under certain conditions, related to the relative scaling of the sensor structure, to minimize the aforementioned problem and thus to construct an inexpensive robust and reliable sensor for industrial use. An optimized system was constructed consisting of two modules the sensing head and an electronics unit connected through coaxial cables. The sensor head contains driving and sensing plates. The electronics unit accompanying the sensor outputs two voltage signals bearing information about the product's relative permitivity and resistivity coefficient. Many factors affecting the sensor head design are discussed. The response of the sensor is investigated in two cases: with and without presence of a ground plane and for various materials with different dielectric constants. Experimental results are also presented that confirm to a great extent the simulation results. Slight discrepancies observed are explained.

Development of a Respiratory Inductive Plethysmography Module Supporting Multiple Sensors for Wearable Systems

Abstract: In this paper, we present an RIP module with the features of supporting multiple inductive sensors, no variable frequency LC oscillator, low power consumption, and automatic gain adjustment for each channel. Based on the method of inductance measurement without using a variable frequency LC oscillator, we further integrate pulse amplitude modulation and time division multiplexing scheme into a module to support multiple RIP sensors. All inductive sensors are excited by a high-frequency electric current periodically and momentarily, and the inductance of each sensor is measured during the time when the electric current is fed to it. To improve the amplitude response of the RIP sensors, we optimize the sensing unit with a matching capacitor parallel with each RIP sensor forming a frequency selection filter. Performance tests on the linearity of the output with cross-sectional area and the accuracy of respiratory volume estimation demonstrate good linearity and accurate lung volume estimation. Power consumption of this new RIP module with two sensors is very low. The performance of respiration measurement during movement is also evaluated. This RIP module is especially desirable for wearable systems with multiple RIP sensors for long-term respiration monitoring.

Sensor arrangement and method for operating a sensor arrangement

Abstract: The invention relates to a sensor arrangement (800) and a method for operating a sensor arrangement. The sensor arrangement contains a plurality of sensor devices (600) embodied on and/or in a substrate. Each of the sensor devices comprises an electric signal converter (601) and a sensor element (602) coupled to the signal converter in order to characteristically influence the electrical conductivity of the signal converter as a result of a sensor event on the sensor element. Each sensor device comprises a device (603) for keeping an electric voltage, which is applied to the signal converter, constant and a device (603) for detecting the value of the electric current flowing through the signal converter in the form of a sensor signal.

Electro-acoustic detection, identification and location of partial discharge sources in oil-paper insulation systems

Abstract: The detection of Partial Discharges (PD) is a reliable technique to analyze the status of electrical insulation in power transformers. Phase resolved partial discharge patterns are being complemented with high frequency pulse waveform analysis, in order to identify discharge sources. In addition to this, acoustic techniques are being implemented trying to locate PD sites in large power transformers. In this work, an inductive loop sensor will be used to identify two different PD sources by means of the energy distribution of the detected waveforms. Additionally, these PD sources will be located by means of acoustic measurements with an electrical reference, through the analysis of the acoustic activity detected for each sensor individually.

A multi-frequency impedance analysing instrument for eddy current testing

Abstract: This paper presents the design of a high-performance multi-frequency impedance analysing instrument (MFIA) for eddy current testing which has been developed primarily for monitoring a steel production process using an inductive sensor. The system consists of a flexible multi-frequency waveform generator and a voltage/current measurement unit. The impedance of the sensor is obtained by cross-spectral analysis of the current and voltage signals. The system contains high-speed digital-to-analogue, analogue-to-digital converters and dual DSPs with one for control and interface and one dedicated to frequency-spectra analysis using fast Fourier transformation (FFT). The frequency span of the signal that can be analysed ranges from 1 kHz to 8 MHz. The system also employs a high-speed serial port interface (USB) to communicate with a personal computer (PC) and to allow for fast transmission of data and control commands. Overall, the system is capable of delivering over 250 impedance spectra per second. Although the instrument has been developed mainly for use with an inductive sensor, the system is not restricted to inductive measurement. The flexibility of the design architecture is demonstrated with capacitive and resistive measurements by using appropriate input circuitry. Issues relating to optimizing the phase of the spectra components in the excitation waveform are also discussed.