Showing papers on "Inductive sensor published in 2006"

The flexure-based microgap rheometer (FMR)

Abstract: We describe the design and construction of a new microrheometer designed to facilitate the viscometric study of complex fluids with very small sample volumes (1–10μl) and gaps of micrometer dimensions. The flexure-based microgap rheometer (FMR) is a shear-rate-controlled device capable of measuring the shear stress in a plane Couette configuration with directly controlled gaps between 1 and 200μm. White light interferometry and a three-point nanopositioning stage using piezo-stepping motors are used to control the parallelism of the upper and lower shearing surfaces, which are constructed from glass optical flats. A compound flexure system is used to hold the fluid sample testing unit between a drive spring connected to an “inchworm” motor and an independent sensor spring. Displacements in the sensing flexure are detected using an inductive proximity sensor. Ready optical access to the transparent shearing surfaces enables monitoring of the structural evolution in the gap with a long working-distance vide...

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.

Magnetic field sensor device

Abstract: A magnetic field sensor device includes at least two magneto-resistive sensor elements and one switch which is connected to the at least two magneto-resistive sensor elements, and makes at least one magneto-resistive sensor element of the at least two magneto-resistive sensor elements electrically connectable into a magnetic field detection arrangement.

Passively shielded inductive sensor system for personnel screening

Abstract: An inspection system includes an electromagnetic shield having electrically conductive sidewalls spaced from one another The shield also includes a conductive third wall which spans the distance between the sidewalls, and is electrically coupled to the sidewalls The inspection system also has an inductive sensor positioned within the electromagnetic shield The inductive sensor has two current branches, which exhibit anti-symmetric current flow Typically, the two current branches are positioned on opposing sides of the medial plane of the electromagnetic shield

Sensor arrangement for a motor-vehicle locking device and an associated method

Abstract: In a method for detecting the application of an operator’s body part to a operating point of a locking device of a motor vehicle, the proximity of the operator’s body part to the operating point is first detected using a proximity sensor and a change in the pressure exerted on the operating point by the operator’s body part is detected using a mechanical sensor which is arranged on the operating point. An output signal which indicates the application of the operator’s body part is generated by an evaluation circuit as a function of the sensor output signals (1, 2) from the proximity sensor and the mechanical sensor. According to the invention, when the evaluation circuit detects the beginning of the application (B) of the operator’s body part on the basis of the sensor output signal (2) from the mechanical sensor, a sensor output signal value (5) which is output at approximately the same time by the proximity sensor is detected and used to evaluate the subsequent changes in the sensor output signal (1) in order to be able to detect in a more reliable manner that the operator’s body part has been withdrawn (1a, 1b) from the operating point. The invention also relates to an associated sensor arrangement.

Closed loop applied to magnetic measurements in the range of 0.1-50 MHz

Abstract: After a brief historical review of inductive sensors used for measuring terrestrial magnetic field variations, this article explains the difficulty in extending the working range of the well known search coil toward high frequencies. The theory of the closed loop magnetometer is exposed and practical considerations leading to an optimized sensor are discussed. Two examples of prototypes are then shown, with the simulated and experimental curves of the transfer function and the noise spectral density. Finally, an experimental facility to measure the sensitivity of the sensor to the pure electric field is shown, and the results of one of the prototypes are presented.

Passenger screening system and method

Abstract: A screening system including a first modality comprising at least one inductive sensor, and a second modality including at least one metal detection coil configured to generate a magnetic field, said induction sensor configured to detect a change in the magnetic field generated by the metal detection coil.

Method and device for distance measurement by means of capacitive or inductive sensors

Abstract: The application relates to a method and a device for measuring the propagation time of capacitive or inductive fields.

Simultaneous Non-contact Measurement of Water Level and Conductivity

Abstract: Measurement of water level and conductivity is important in many applications, including geophysics, ocean engineering, and the oil industry, one example being gas/oil/water separation. Non-contact measurement is ideal for those applications. Capacitance, radar, ultrasonic and laser techniques have been used in measuring level, but simultaneous measurement of level and conductivity has not been reported. In this paper, we developed a novel inductive sensor, which uses two coils of different size to infer conductivity and level simultaneously based on a simplified model deduced from an analytical solution. The simplified model is verified with both simulation and experimental data. The experimental results have shown that measurement accuracy for both level and conductivity are within 3%.

Wireless sensor antenna configuration

Abstract: Many sensors could be used in a passive wireless mode. These include RLC, acoustic wave and magneto-elastic sensors. These types of sensors are designed to exhibit a change in fundamental frequency when exposed to environmental factors such as temperature, pressure, or chemicals. An interrogation circuit can inductively couple to the sensor and measure the change in fundamental frequency. The change can be used to measure the environmental factor. Sensor sensitivity and inductive coupling efficiency can be competing design constraints. A driver, electrically connected to the sensor and inductively coupled to the interrogation circuit, can relax the constraints. The driver, however, can introduce noise into the sensor. The sensor can be shielded using physical and geometric techniques to reduce the noise.

Design and signal processing of a magnetic sensor array for train wheel detection

Abstract: This paper proposes a train wheel detection system based on the use of an inductive sensor array. It allows multiple detection points and uses coded signals in order to work with low signal to noise ratios. The sensor array consists of pairs of sensor coils placed at every detection point. In this work, unlike previous work about this matter, the coils are interconnected in series as a part of a Maxwell bridge that is used to excite the coils and to receive the unbalance signal when there is a perturbation caused by the train pass over the detection point. Furthermore, the signal used is encoded with complementary sequences, allowing a single process of many detection points. Finally, the gain of the process allows placing the signal-processing module far away of the detection point, which makes it possible to work with a detector system without electronics near the railways.

Device for measuring rotational and translatory movements

Abstract: The device has a rotatable sensing wheel (1) attached to a magnetic pole (2), which transmits a signal. A sensor (3) detects the signal transmitted by the pole (2) for detecting rotational angle and/or angular speed of the wheel, where the sensor is formed as hall sensor, difference hall sensor, magneto-resistance sensor, giant magneto-resistance sensor or inductive sensor. Another two magnetic poles (4, 5) detect a translatory movement, which is superimposed on a rotating movement of the wheel, where the poles (2, 4, 5) are arranged at an outer circumference of the wheel.

A built-in displacement sensor for an electrostatic film motor

Abstract: This paper proposes and evaluates a built-in position sensor for an electrostatic motor called a dual excitation multiphase electrostatic drive. The built-in sensor operates on a similar principle to typical capacitance-type linear encoders. The sensor system superimposes a high-frequency sensor signal onto a low-frequency driving signal so that it can share the same electrodes with driving operation of the motor. This paper analyses the sensor principle based on a capacitance network model of the motor that allows us to evaluate the linearity error of the proposed sensor system. The sensor was implemented on a prototype motor to evaluate its performance. The experimental results confirmed that the sensor can work successfully by sharing the same electrodes with the driving operation. The linearity error was found to be 24 ?m when no driving signal was applied. As the driving signal was applied, the linearity error was found to increase up to 48 ?m.

Capacitive proximity switch and household appliance equipped therewith

Abstract: The invention relates to a capacitive proximity switch (4) with an electrically conductive sensor surface (7), which is covered by an electrically non-conductive covering plate (2) and which serves as a part of a capacitor (17) with a capacitance that varies with proximity. The proximity switch (4) comprises a reference sensor surface (10) for generating a reference signal for determining an actuation state of the proximity switch (4). Signal portions of the reference signal are proportional to the capacitance of a reference capacitor formed with the reference sensor surface (10), and the capacitance of the reference capacitor is determined by surrounding conditions of the sensor surface (7).

Design of an Inductive Long Displacement Measurement Instrument

Abstract: To enlarge the measuring range of inductive displacement sensor, the proposed displacement measurement instrument consists of four elements: the first is a movable coil with short length supplied with DC voltage. The second is a fixed iron rod acting as a core, its shape is designed carefully and the cross-section is varying along the axis. The third is an iron cover. It works as the external path of magnetic flux. When the coil moves on the rod, the current induced in the coil is proportional to the axis-direction displacement of the iron rod. The last one is a measurement circuit used to transform the current signal to the voltage signal and then processed by a microprocessor. This sensor offers excellent features of smart structure, low cost, large sensing length (1400mm), high accuracy (0.5%) and good linearity. An application of this instrument has been put on use in the underwater displacement measurement of a water station lift-gate control system.

Electronic nose sensor array, sensor system including the same, method of manufacturing the same, and analysis method using the sensor system

Abstract: Provided are an electronic nose sensor array which can easily measure and process a sample using a personal information terminal and can be mass-produced, a sensor system including the same, a method of manufacturing the electronic nose sensor array, and a analysis method using the electronic nose sensor system. The sensor array comprises a plurality of sensing films which are formed on a side of a polymer substrate and react to chemical species to be analyzed, thereby changing their electric resistances, and a plurality of sensing electrodes, each of which contacts both ends of each of the sensing films and senses a change of one of the electric resistances.

Sensor device for a heating device

Abstract: The invention relates to a sensor (11) on a sensor device on a cooking hob, provided with contacts (14) on a support (13), an electronic circuit (16) for signal processing and a resistance track (18) for temperature measurement. Said sensor is arranged in a tubular housing (22) above a radiant heater (26). The metallic housing (22) is operated as an electromagnetic pan recognition sensor. The functions of temperature measurement and pan recognition can thus be advantageously combined in a sensor device as a module. A good transmission of sensor signals can be achieved as a result of the physical proximity of the sensor signal processor (16) to the sensor (11).

Angular position inductive sensor

Abstract: The invention concerns an angular position inductive sensor, comprising a partly metallized disc mobile in rotation about its axis of revolution and a stator including a primary coil and a plurality of secondary coils, said secondary coils being arranged in pairs substantially symmetrical relative to said axis of revolution, so as to form one or more pair(s) of secondary coils, said secondary coils of each pair being connected to one another in series and in phase-opposition relative to one another and to the terminals of measuring means adapted to generate an output signal based on the voltage at the terminals of said pair.

Electronic proximity switch

Abstract: An electronic proximity switch employs two oscillators coupled through two electrical paths, one associated with an antenna serving as a proximity switch sensor. Absorption by an object near the antenna changes the coupling between the oscillators producing a dramatic phase shift that may be detected and used for switching purposes.

New Non-contacting Linear Displacement Inductive Sensors for Industrial Automation

Abstract: Non-contacting inductive sensors are applicable on a large scale for position detection or travel measurement in industrial applications due to their wear-free sensing of the target (any metal object), reliability, robustness, resistance to fouling, water tightness and compact size. Mostly these sensors are realized as inductive proximity sensors (IPS), which convert the distance between the target and sensor active face into an electrical analog or binary signal. Because of physically given factors, the resulting measuring ranges are relatively limited. There are basically two approaches to convert an analog IPS into a displacement sensor with a large measuring range: either mechanical means or modification of the sensor primary transducer. The first approach is implemented in a popular mechanical method, which converts the linear travel into a distance change with a metal incline. Unfortunately, the linearity, accuracy and repeatability of the IPS are downgraded by the incline's conversion ratio. In order to render the mechanical conversion unnecessary while preserving the qualities of the IPS, we developed a new non-contacting linear displacement inductive sensor (LDIS) family. Due to its flexibility and compact construction, it is ideal for numerous industrial applications and even opens up areas for new implementations.

Proximity sensor interface

Abstract: A first measured value is determined which is associated with the proximity of a target to an inductive sensor. A first voltage signal having a first amplitude is generated. The first voltage signal is provided as a driving signal to the inductive sensor. A sensor current signal is received as a return signal output from the inductive sensor. The sensor current signal has an amplitude proportional to a proximity of the target to the inductive sensor. The sensor current signal is converted to a corresponding second voltage signal having a second amplitude. A differential measuring technique is used to determine the first measured value in accordance with relative amplitudes of said first voltage signal and said second voltage signal.

Device for activating inductive loop sensor of a traffic light control system

Abstract: A system and method for activating vehicle sensors which are based on inductive loops. A voltage controlled oscillator is scanned throughout the required frequency range while a balanced mixer, low-pass filter, and detector are arranged to show the presence of a signal from an inductive loop by the amplitude of the resultant signal at a difference frequency. The voltage controlled oscillator is then made to dwell at or near the frequency of the sensor loop by adjusting so as to keep the amplitude of that low-frequency difference as high as possible.

Inductive sensor for detecting presence of contact less metallic article, has coils and capacitance that are connected to LC-circuit, where coils are arranged in window wall, and capacitance and coils are adjacent to each other

Abstract: The sensor has a housing, which consists of a circumferential wall and a window wall, where a rear wall lies opposite to the window wall. Coils (48, 50) and a capacitance are connected to a LC-circuit. The coils are arranged in the window wall, and the capacitance and the coils are adjacent to each other. One of the coils is designed as a conductive strip of a printed circuit. Inner surface of the housing are connected with grooves.

Study of Rotor Position Detection Method for Linear Synchronous Motor

Abstract: It is necessary to detect rotor position accurately for field oriented control system of synchronous motor.A new method is forwarded to detect the rotor position for linear synchronous motor in high speed maglev train based on inductive sensor and DSP.The hardware of the inductive sensor,the teeth-slot signals detection principle of long stator,and signals processed with DSP are elucidated.Measurement accuracy and tolerances are analyzed,and several improvements are also presented.In the speed and positioning experiment system of high speed maglev train,the measurement accuracy is less than 3° of the winding pitch of the long stator and can meet the requirement of the operating control system of high-speed maglev train.

Proximity sensor and proximity detection method

Abstract: A proximity sensor such as a proximity switch, a displacement sensor, a distance sensor, a material sensor, a coin sensor, a metal sphere sensor for detecting the proximity of metal, with which to measure the phase shift and the amplitude change of a vibration wave caused by metal proximity accurately by a simple circuit structure. A proximity sensor (1) for detecting the proximity of metal, which is provided with a resonating circuit (2) consisting of a capacitor C connected wit a detection coil L, which outputs a drive signal to the resonating circuit (2), and which measures a phase shift and an amplitude change caused by metal proximity based on a free vibration wave output in a dampening manner from the resonating circuit (2) after the signal output of the drive signal stops.

Capacitive proximity switch, and domestic appliance equipped with the same

Abstract: A capacitive proximity switch has an electrically conductive sensor surface, which is covered by an electrically non-conductive covering plate and which serves as a part of a capacitor with a capacitance that varies with proximity. A household appliance is equipped with a proximity switch of this type. The sensor surface has an active shielding, which is formed by a shielding surface to which a clock signal is applied at the same time as it is applied to the sensor surface.

Eddy-current Type Proximity Sensor with Closed Magnetic Circuit Geometry

Abstract: The eddy-current type proximity sensor is a noncontact type sensing device to detect the approach of a conductor by increase of coil resistance due to eddy-current loss. This paper proposes to add the cap-shaped magnetic flux shield at the top of the ferrite core for the actual sensor. In conventional proximity sensors, main magnetic flux path passes through the air between the target conductor and ferrite core. The proposed sensor, in contrast, has closed magnetic circuit geometry. This means that main magnetic flux path is almost completed by the core and the shield. Therefore, it is predicted that flux does not reach the target conductor and it causes debasement of sensing property. However, it is shown that the calculated results by finite element method and measured results of the sensing property of the proposed sensor is enhanced compared with the actual sensor. This paper quantitatively accounts the electromagnetisms of the proposed sensor from sensing property, flux distributions, and eddy-current loss in each part of the sensor body

Mechanical support device and a measuring device with a mechanical support device

Abstract: A mechanical support device (10) for a sensor plate (18) of a device for transmitting and/or receiving electromagnetic high-frequency signals, is designed as a winding core (24, 26) of at least one coil (32, 32′, 32″; 34, 34′, 34″; 36, 36′, 36″) in an inductive sensor.