Showing papers on "Inductive sensor published in 2005"

Inductively Powered Mobile Sensor System

Abstract: An inductively powered sensor system includes a primary conductive path 100 capable of being energised to provide an electromagnetic field in a defined space 1. An inductive power pick-up 120 is associated with a sensor 124 and is capable of receiving power from the field to supply the sensor 124. The system includes a first sensing means to sense the power available to the pick-up 120 and control means to increase or decrease the power available to the sensor dependant on the sensed power available. A method of inductively powering a sensor, an inductively powered sensor and an animal enclosure including one or more primary conductive path of an inductive power supply are also disclosed.

Inductive tilt sensor with magnets and magnetic fluid

Abstract: The paper presents a new type of tilt inductive sensor using four magnets and a magnetic fluid. The determination of the sensor sensibility is performed with theoretical predictions based on the potential magnetic energy function of the assembly constituted by two repulsion magnets. This energy function is experimentally determined. The sensor sensibility varies in conformity to a power law depending on the initial distance between two repulsion magnets. The sensor supplies a signal proportional with the tilt.

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.

Digital magnetic current sensor and logic

Abstract: A sensor for sensing magnetic field strength has a sensor element, and detection circuitry for detecting a level of resistance of the sensor element, the level of resistance varying with magnetic field under test and having hysteresis, so that upon electromagnetic excitation the resistance can switch between two or more stable levels as the magnetic field under test varies. The sensor outputs a digital signal according to the level of resistance. The sensor output may further be interpreted in terms of a change-of-state upon electromagnetic excitation. As the sensor no longer needs a different characteristic from magnetic memory cells, it can be much easier to construct and to integrate with magnetic memory cells than an analog sensor. An excitation signal varies a threshold for the magnetic field under test at which the resistance switches, to enable multiple measurements with different thresholds. Multiple sensor elements can have different thresholds, by having differing geometry or size. It has applications in current sensing, and programmable magnetic logic, when multiple input currents are sensed. Changing the threshold can change the logic operation between AND and OR.

Inductive sensor unit

Abstract: Sensor coils (L1-L5,L1'-L5') attach to a printed circuit board (3) in a planar manner. A conductive activating element (CAE) (7) i.e. a forked metal plate fits with a clearance (a) at either side above the sensor coils on a track. An electric evaluatory circuit detects inductance changes in the sensor coils corresponding to the CAE's track position.

On-line partial discharge detection of MV cables with defect localisation (PDOL) based on two time synchronised sensors

Abstract: A new and unique measuring system is presented for the online acquisition and analysis of partial discharges (PD-s) in medium-voltage power cables. The system is able to locate the origin(s) of PD-s by using two inductive sensors, each at one cable end. The measuring system is called PDOL, which stands for PD detection On-line with Localization. A patented solution is used for the time synchronization of the data intake at both cable ends and for the on-line calibration. One computer at a remote location collects data from various PDOL measuring systems for final presentation and interpretation. This paper discusses the basics of PDOL and some first measurement results.

Inductive sensor based on nano-scale SQUIDs

Abstract: Detectors with sufficient sensitivity to resolve the energy of single photons and particles combined with rapid response times are becoming increasingly important. We describe work in progress on a recently-proposed type of sensor, which we have named the Inductive Superconducting Transition Edge Detector (ISTED). We have theoretically estimated the energy sensitivity of such a sensor, in the case where the heat absorber is incorporated within the sensitive area of a nano-scale SQUID which acts as an inductive readout device. Recent results on the experimental characterization of prototype devices in the temperature range 5-8 K are presented, and ongoing work which is intended to achieve smaller device dimensions together with lower operating temperatures is described.

Sensor unit with staggered actuation faces

Abstract: An inductive sensor for detecting the position of a vehicle seat or for a gate shifting unit of an automatic transmission is described. The inductive sensor unit has a plurality of sensor coils that are disposed in planar fashion on a printed circuit board A conductive actuation element is guided, spaced apart, in a path over the sensor coils and an electrical evaluation circuit detects changes in inductance of the sensor coils in accordance with the path position of the actuation element and converts the changes into electrical signals corresponding to seat position signals on gear shifting signals. The actuation element is guided along the sensor coils with conductive bottom faces that are staggered in the direction of the path.

A combined Q and heterodyne sensor incorporating real-time DSP for reinforcement imaging, corrosion detection and material characterisation

Abstract: An inductive sensor is described that is used to image steel reinforcement bars in concrete and to visualise surface corrosion. When a conductive target is placed within the vicinity of the sensing coil, an EMF is induced that opposes the change producing it. This causes a reduction in the Q -factor of the coil and a fall in amplitude of the excitation signal. When a non-conducting ferrous target such as corrosion product is present, a local increase in magnetic flux density occurs that in turn causes the inductance of the sensing coil to increase, reducing the resonant frequency of the tuned-system. The changes in Q -factor and resonant frequency are measured to image both the parent steel and surface corrosion. The circuit is designed to respond to very small changes in the received signal amplitude via a sensitive gain system, and to small changes in frequency, through the application of heterodyning. The excitation frequency has been selected so that the skin effect restricts the flow of eddy currents to the surface of the target. In this manner, surface features such as cracks and corrosion may be identified. The measured parameters are ultimately expressed as voltages before being applied to a purpose-designed DSP system. This averages signals in real-time, allowing high speed scanning. Feedback stabilisation is also applied between the DSP system and sensor to minimise voltage drift. At present it is possible to detect a steel bar to a depth of 200 mm and to image steel and surface corrosion to a depth 60 mm. Additionally, it is possible to image a range of materials for which non-destructive testing is important, such as graphite rods used in the nuclear industry. Since eddy currents are disrupted by vertical cracks, these features are readily detected by the system.

Scrap Metal Sorting with Colour Vision and Inductive Sensor Array

Abstract: This paper presents a novel automatic scrap metal sorting system which employs a colour vision based optical sensing system and an inductive sensor array. The operation of the system is verified in a real metal recycling plant. The long period test results indicate that 80 % purity can be achieved when the feeding conveyor speed is limited below 1,5 m/s. The described system is not designed for any particular metal. However, the above separation result can only be achieved when reddish (brass, copper) and bright metals (stainless steel) are separated. The properties of aluminium, zinc, and magnesium are too similar for the current sensing principle. The results do not only depend on the sensing system, but also optimal work flow, lighting, dust and vibrations have to be considered in a practical sorting machine. The achieved purity and capacity is sufficient for industrial use. Efficient use of sensor fusion provides good performance despite the diversity of the scrap metals

Closed-loop magnetic sensor system

Abstract: A closed loop magnetic sensor system for measuring an input magnetic field from a magnetic field source has a compensation circuit, which can be for example a printed wire board, and a magnetic sensor, such as a Magnetoresistive (MR) sensor, for measuring an input magnetic field. Preferably, the magnetic sensor is magnetically coupled to the compensation circuit by arranging the magnetic sensor in an air gap provided in the compensation circuit. The compensation circuit has a compensating conductor, arranged on or in a dielectric medium, which can be configured as a plurality of nested coils. Electrical control circuitry, electrically, coupled to the magnetic sensor and compensating conductor, is adapted and arranged to drive a feedback current through the compensating conductor according to the output of the magnetic sensor such that the input magnetic field is substantially compensated at the magnetic sensor. The magnetic system can serve as current sensor for sensing current through a primary conductor.

Integrated inductive sensors for the detection of magnetic microparticles

Abstract: In this paper, we deal with novel inductive microsensors, realized by using standard CMOS microelectronic technologies, for the detection of small amounts of magnetic beads that are placed in selected regions over the surface of the microsensor. The sensor proposed here represents a step toward the development of integrated inductive biosensors for application in the area of magnetic immunoassay where magnetic markers, carrying specific antibodies that selectively bind to the cells or molecules to be detected, are used; the measurement of the analyte concentration is therefore accomplished by determining the concentration of magnetic particles tied to it. A planar differential transformer structure is proposed here as part of the measurement strategy. The analysis, simulation, and design of the proposed device are reported, and its sensitivity to the quantity of micromagnetic beads deposited over its surface has been also demonstrated through experiments.

Inductive sensor for vehicle electronic throttle control

Abstract: An apparatus for allowing electronic engine speed control comprises a transmitter coil, a receiver coil providing a receiver signal when the transmitter coil is excited due to an inductive coupling to the transmitter coil, and a coupler element mechanically associated with a pedal arm so that the coupler position is correlated with the pedal position. The coupler element modifies the inductive coupling between the transmitter coil and the receiver coil so that the receiver signal is correlated with the pedal arm position.

Passive hybrid lc/saw/baw wireless sensor

Abstract: An acoustic wave device can be used in a passive sensor when an interrogation signal is inductively coupled into the sensor. The advantage of inductive coupling is that the interrogation signal can power the sensor. The acoustic wave device can be sensitive to environmental factors, such as pressure, temperature, or chemicals. An environmental factor can cause a change in the acoustic wave device resulting in changing the sensor's fundamental frequency. An interrogation circuit containing a grid dip oscillator can produce the interrogation signal, detect the sensor's fundamental frequency, and thereby produce a measurement of the environmental factor.

Integrated fluxgate-induction sensor

Abstract: An integrated fluxgate-induction sensor is formed of a combined fluxgate sensor and induction sensor using a common core. The sensor may be in serial operation where it switches between a fluxgate mode for measuring static magnetic fields and an induction mode for measuring alternating magnetic fields. Additionally, the sensor may be used in an interleaved operation where the sensor operates from the fluxgate mode during the transition period where its core is changing from a high permeability state to a low permeability state or vice versa, while the sensor operates in the induction mode when the core is in its high permeability state. The resulting sensor provides for a compact magnetic sensor system capable of sensing magnetic fields which oscillate from zero frequency to 10 kHz and higher.

Segmented field sensors

Abstract: Inductive sensors measure the near surface properties of conducting and magnetic material. A sensor may have primary windings with parallel extended winding segments to impose a spatially periodic magnetic field in a test material. Those extended portions may be formed by adjacent portions of individual drive coils. Sensing elements provided every other half wavelength may be connected together in series while the sensing elements in adjacent half wavelengths are spatially offset. Certain sensors include circular segments which create a circularly symmetric magnetic field that is periodic in the radial direction. Such sensors are particularly adapted to surround fasteners to detect cracks and can be mounted beneath a fastener head. In another sensor, sensing windings are offset along the length of parallel winding segments to provide material measurements over different locations when the circuit is scanned over the test material. The distance from the sensing elements to the ends of the primary winding may be kept constant as the offset space in between sensing elements is varied. An image of the material properties can be provided as the sensor is scanned across the material.

Sensor device, method and device for monitoring a sensor device, and system having a sensor device

Abstract: A sensor device is disposed in a wheel. It contains an acceleration sensor, the measurement signal of which is representative of the acceleration of the sensor device. Detachment of the sensor device from its mounting position is detected according to the measurement signal of the acceleration sensor. The sensor device can also contain a position sensor, the measurement signal of which is representative of a relative position of the sensor device based on its mounting position. The sensor device can also contain a deformation measuring element disposed in such a way that a measurement signal of the deformation measuring element exhibits a characteristic oscillation if the sensor device has become detached from its mounting position.

Magnetic Sensor System

Abstract: A magnetic sensor system (1) is provided that contains sensor elements (5, 6) that are sensitive to magnetic fields, the electrical properties of said sensor elements being modifiable according to a magnetic field that can be influenced by a mobile, passive transmitter element (8). The magnetic sensor system (1) includes two sensor elements (5, 6) in a gradiometer system, each of which is assigned to one of two permanent magnets (2, 3) having a predetermined separation. In terms of their dimensions, separation and position relative to the sensor elements (5, 6), the permanent magnets (2, 3) are located such that the offset of the output signal of the sensor elements (5, 6) is minimized in the gradiometer system.

Theoretical progress and recent realizations of miniaturized inductive sensors for automation

Abstract: Non-contacting inductive proximity sensors (IPS) are widely preferred for position detection in industrial applications. Advances in the last 10 years in integration and assembly techniques have made possible continued sensor size reduction towards very small, miniaturized versions. The paper refers to the progress in the last years, presenting the recently gained knowledge in sensing principle, evaluation electronics and manufacturing. The fundamentals shown in the paper were essential for the design and development of a worldwide innovation: the smallest single-component IPS family having the longest switching distance. Mounted in a stainless steel tube with only 3mm diameter and a length of 33mm, the smallest sensor in the family is able to detect metal targets up to 3mm and to provide an output switching signal with high current capacity

Sensor element, e.g. for detecting rain on vehicle or aircraft, has additional temperature-dependent area which compensates for change in capacitive or inductive value

Abstract: The sensor has a dielectric substrate (101) to which a conductive structure (130) is applied comprising an inductive and/or capacitive component that is influenced by the substrate. The substrate has a first temperature-dependent area (120) which is formed such that a varying temperature changes the value of the inductive and/or capacitive component. A second temperature-dependent area (110) is formed such that a varying temperature changes the value of the inductive and/or capacitive component so as to compensate for the change n the first area. Independent claims are included for a temperature-corrected measuring system and a method of manufacturing a sensor element.

Inductive apparatus and method for measuring compressor blade tip clearance in a gas turbine engine

Abstract: An apparatus and a method for measuring the clearance between the blade tips of the compressor blades of a rotatable compressor assembly and the housing in which the compressor assembly is mounted in a gas turbine engine are disclosed. The apparatus includes an inductive proximity sensor disposed in the housing and positioned in close proximity to but not touching the blade tips of the compressor blades of the compressor assembly. The inductive proximity sensor is adapted to generate a magnetic field and to sense changes in the magnetic field as the compressor assembly is rotated and the blade tips are sequentially brought into close proximity to the inductive proximity sensor. The inductive proximity sensor is mounted in one or more alignment ports defined in the housing of the gas turbine engine. A device displays the clearance between the inductive proximity sensor and the blade tips of the compressor blades of the rotatable compressor assembly.

Segmented core for an inductive proximity sensor

Abstract: An inductive proximity sensor for sensing the presence of target based on a change of inductance in the sensor. The sensor includes a coil and a core formed of a permeable material so as to form an electromagnetic field when the coil is electrically driven. The core has a base, a central post, an outer wall, and at least one slot. The central post extends distally from the base and through the coil and defines a distal end. The outer wall extends distally from the base and around the coil and also defines a distal end. The slot or slots are for enhancing the performance of the sensor by reducing eddy current losses in the core. Each slot extends at least partially along a path defined from the distal end of the outer wall to the base and from the base to the distal end of the central post.

Moisture protection for an electromagnetic coil

Abstract: A coil for an inductive sensor, such as a coil which is used in a sensor that operates according to the principle of electromagnetic force compensation for converting an amount of force generated by a load applied to a force-measuring cell into an electrical signal, is provided with protection against the penetration of moisture. The protection includes a protective covering with a surface-smoothing undercoating applied to the coil, on which a second level of coverage is applied as a protective coating against the penetration of moisture.

Modular rotation sensor unit head has exchangeable shaft flange module and capacitive or inductive sensor emitting signal from flange signal source with alignment pin to ensure same reference

Abstract: A modular rotation sensor unit (10) head (12) has an exchangeable shaft flange module (14) and capacitive or inductive sensor (20) emitting a signal from a flange signal source (50) with open side (18) housing (16) interface using an alignment pin (28) and detachable circuit board (22) to ensure that all flange modules have the same reference. Independent claims are included for the shaft flange module.

A preliminary study on a torque sensor for tool condition monitoring in milling

Abstract: The measure of cutting forces is one of the most usual methods in Tool Condition Monitoring (TCM). In this paper a cutting torque sensor for tool condition monitoring in milling is proposed. The device is based on inductive sensors that measure the relative rotation, due to the cutting torque, of two slotted disks fitted on the toolholder; a modification of the toolholder has been required to enhance the sensitivity of the device. During a preliminary stage, the measuring system has been designed and the optimization of the toolholder dimensions has been carried out by using both simplified and FEM-based approaches. To check the feasibility of the proposed device, a mechanical simulator installed on a lathe has been realized and its performance has been tested under different cutting conditions. The results show the validity of the method and encourage the use of the modified toolholder as instrument for tool condition monitoring.

Position sensor for a fluid cylinder

Abstract: The system has magnetic or inductive sensor (2) arranged in guide groove (20) on exterior of working cylinder (16). A positioning device is operably coupled to the sensor, for adjusting the sensing positions of sensor.

A New Position Sensor Using a Triangularly Shaped Piezoelectric PVDF Film

Abstract: This paper describes a novel tip position sensor for a cantilever beam made of a triangularly shaped distributed piezoelectric PVDF (polyvinylidene fluoride) film. Due to the boundary condition of the cantilever beam and the spatial sensitivity function of the distributed PVDF sensor, the charge output of the PVDF sensor can be shown to be proportional to the tip position of the beam. Experimental result using the triangular PVDF sensor were compared with those using two commercially available position sensors: an inductive sensor and an accelerometer (after double integration). The resonance frequencies of the test beam, measured using the PVDF sensor, matched well with those measured with the two commercial sensors and the PVDF sensor also showed good coherence over wide frequency range, whereas the inductive sensor became poor above 300Hz. However, the measured response of the PVDF sensor showed a bit larger magnitude compared with the two commercial sensors at higher frequencies. The triangular PVDF sensor have a number of advantages over conventional position sensors and could be used as tip position sensors.

Pulling of SAW resonators for wireless sensor application

Abstract: SAW resonators are particularly suitable for passive wireless sensing because of the high Q factor (storage of rf energy) and the possibility to change their resonance be- haviour influenced by an external measurand (frequency pulling). The sensor is build not only by a physical af- fecting of the acoustic wave but also by an electrical interaction outside the resonator (e.g. capacitive or inductive). The sensor signal is determined by the ex- ternal circuit elements and manifests in a fre- quency and amplitude shift. The pulling frequency and the optimum pulling span, also the transmitted power are estimated by the external reactive circuit ele- ments, as well as by the SAW-Resonator characteristic. To obtain the maximum power transmis- sion, a matching between the sensor element and the antenna for wireless interrogation is necessary; simultaneously, one element of the matching network is the sensing element that pulls the frequency. For well-designed sensors, the parameters of equivalent circuitry of the resonator have to be estimated with a high accuracy, in order to simulate the resonator pulling in combination with different matching networks. Thus, from all the L-, Pi- and T-sections, the eligible con- figuration were selected and tested in order to ensure the maximum power transmission in a wide pulling range. This paper presents simulation and ex- perimental results for designing proper sensor systems.

Method for operating a sensor

Abstract: The invention relates to a method for operating a sensor (1), particularly a yaw rate sensor, which is housed inside a housing (10). In order to detect the dangerous influence of mechanical vibrations upon the output measured value of the sensor (1), the vibrations are sensed at the location of the sensor (1), and the sensor (1) or an electronic device (3) interacting with the sensor (1) is switched off so long as the vibrations exceed an established intensity. The method can be used, in particularly, in a driving dynamics control (FDR) of a road vehicle.