Showing papers on "Inductive sensor published in 2012"

A Multiple Inductive Loop Vehicle Detection System for Heterogeneous and Lane-Less Traffic

Abstract: This paper presents a novel inductive loop sensor that can detect vehicles under a heterogeneous and less-lane-disciplined traffic and thus can be used to support a traffic control management system in optimizing the best use of existing roads. The loop sensor proposed in this paper detects large (e.g., bus) as well as small (e.g., bicycle) vehicles occupying any available space in the roadway, which is the main requirement for sensing heterogeneous and lane-less traffic. To accomplish the sensing of large as well as small vehicles, a multiple loop system with a new inductive loop sensor structure is proposed. The proposed sensor structure not only senses and segregates the vehicle type as bicycle, motor cycle, scooter, car, and bus but also enables accurate counting of the number of vehicles even in a mixed traffic flow condition. A prototype of the multiple loop sensing system has been developed and tested. Field tests indicate that the prototype successfully detected all types of vehicles and counted, correctly, the number of each type of vehicles. Thus, the suitability of the proposed sensor system for any type of traffic has been established.

Combined force and proximity sensing

Abstract: Combined force and proximity sensing is disclosed. One or more sensors can concurrently sense a force applied by an object on a device surface and a proximity of the object to the surface. In an example, a single sensor can sense both force and proximity via a resistance change and a capacitance change, respectively, at the sensor. In another example, multiple sensors can be used, where one sensor can sense force via either a resistance change or a capacitance change and another sensor can sense proximity via a capacitance change.

System and method for detecting, characterizing, and tracking an inductive power receiver

Abstract: A system and method for detecting, characterizing, and tracking an inductive power receiver proximate to an inductive charging surface of an inductive charger. One or more resonators and one or more sensors provide information that can be utilized to detect, characterize, and track the inductive power receiver. The resonators can be configured to determine position of a remote device using magnitude or phase of sensors associated with resonators. In addition, by monitoring the inductive power transmitter and the resonators, the charger can differentiate between whether parasitic metal is present, a remote device is present, or both are present.

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.

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.

Boundary Sensor Assembly for a Robotic Lawn Mower, Robotic Lawn Mower and Robotic Lawn Mower System

Abstract: A robotic mower sensor assembly for detecting a boundary wire signal The sensor assembly includes a plurality of analog inductive sensors with a first inductive sensor oriented along a first axis and a second inductive sensor oriented along a second, different axis Each inductive sensor is configured to generate a signal indicative of the distance of the robotic mower from the boundary wire A control unit communicating with the sensor assembly is configured to operate the robotic mower in response to the signals from the sensor assembly which are indicative of the distance of the robotic mower from the boundary wire

Inductive Sensor for Temperature Measurement in Induction Heating Applications

Abstract: A new inductive sensor for temperature measurement in domestic induction hobs and results of its applications are presented. It consists of a coil and a resonant electronic circuit which measures the impedance variation of ferromagnetic pots when their temperature changes. This sensor has promising applicability in induction hobs because it has instantaneous response, it is cheap, and contactless. The performance of the sensor is tested in the cooking range from 20°C to 220° C with pots of different materials, revealing a measurement error lower than 6°C. This error is much lower than that obtained from measurements with current sensing systems installed in induction hobs, namely a thermistor measuring the temperature of the glass in the cooking zone. The proposed sensor will allow fire prevention in cooking processes with a cost comparable to that of conventional measurement systems.

Capacitive/Inductive Proximity Detection for Wi-Fi Protection

Abstract: A combination of capacitive, mutual capacitive, and inductive proximity and touch sensing is used to detect the presence and nature of nearby objects to a wireless device. When the proximity of metal or a user is sensed the output power of a Wi-Fi module in the device is reduced so as to prevent harm to the user and/or the Wi-Fi transmitter amplifier circuits. Inductive sensors located at the four corners of the wireless device are used to detect metal, and capacitive sensors are used to detect a capacitance change or shift due to the presence of a user's hand, body or metal. In addition, the capacitive sensors may be located at the four corners of the device and can measure changes in the mutual capacitance coupling between these capacitive sensors.

Material-discerning proximity sensing

Abstract: A material-discerning proximity sensor is arranged to include an antenna that is arranged to radiate a radio-frequency signal. A capacitive sensor is arranged to detect a change in capacitance of the capacitive sensor and to receive the radio-frequency signal. An electrical quantity sensor is arranged to detect a change of the received radio-frequency signal.

A LTCC low-loss inductive proximity sensor for harsh environments

Abstract: Proximity and position measurements with eddy current sensors are limited by the quality factor of the sensing coils. By enlarging the conductor path cross section, the quality factor can be increased. On ceramic multilayer substrates such cross sections, which are considerably larger in comparison to screen printed thick films, can be manufactured with an embossing and filling procedure, which is integrated into the conventional fabrication process. The conductor path layout is molded into the unfired ceramic substrate prior to filling the trenches completely with the conducting paste, thus generating a large cross section. This technique is applied for the sensing coil of an eddy current sensor. The higher quality factor leads to a doubled sensitivity in comparison to conventionally screen printed sensors. Due to the thermal and chemical durability of the ceramic substrate, the coils can be directly applied in a variety of harsh environment conditions, such as in situ engine monitoring.

Instrumentation circuitry for an inductive wear debris sensor

Abstract: The design of instrumentation circuitry for an inductive sensor to detect small metal particles is presented. The sensor, designed for counting and characterizing wear debris particles in lubrication oil, detects changes in the inductance of a small coil as metal particles pass through it. A change in inductance produces a differential voltage at the output of a Maxwell-Wien bridge, which is then amplified and rectified to produce a DC voltage pulse detectable using standard data acquisition components. For iron particles approximately 75µm and 150µm in diameter, the circuit produces output voltage pulses of 381mV and 693mV, respectively.

Analysis of signals from inductive sensors by means of the DasyLab software

Abstract: The paper deals with the acquisition of measuring signals from inductive sensors and their treatment in the programming environment National Instruments DasyLab. Its potential is presented with respect to analyzing and processing the data and the methods of constructing algorithms for performing complex tasks are discussed. Signals coming from inductive sensors are typically sinusoidal or deformed, of irregular shapes. They carry various types of information: on the thickness of the outer coating, on the flaws in the coating, or on the linear or angular displacement. In order to obtain such information from the measuring sensor it is necessary to examine the amplitude, frequency, or shape of the measuring signal analysed. Such signals can be examined as individual impulses of various shapes or as sets of periods extending over longer time spans. The paper also describes the examples of the systems in the DasyLab software package to be used in measurements and other forms of applied research.

Resonant Coupling of a Passive Inductance-Capacitance-Resistor Loop in Coil-Based Sensing Systems

Abstract: An inductance-capacitance-resistor (LCR) loop is composed, by connecting an inductive coil with a capacitance element end by end. Without any electric connection with other circuits, higher quality factor can be easily obtained. The loop is inserted into the electromagnetic coupling path of coil-based sensing system, such as the case of eddy-current sensor. When the system is working at the natural resonant frequency of the loop, the coupling efficiency and, therefore, the sensing performance could be improved significantly. Protocol systems, simulating the operation cases of wireless passive sensor and eddy current proximity sensor, are constructed and tested experimentally. The results indicate that, in case of coil-coupled wireless passive sensing system, the received signal's amplitude is enlarged remarkably with a coaxially inserted LCR loop. Moreover, when the loop is coaxially placed on top of the sensing coil of eddy current sensor, not only higher sensitivity and resolution, but also larger monotonic detection range could be achieved.

Differential proximity sensing and side detection for an electronic device

Abstract: An electronic device includes a housing enclosing a motion sensor and a first capacitive proximity sensor on a first planar side of the electronic device. A second capacitive proximity sensor on a second planar side of the electronic device within the housing is monitored for determining the differential amount of signal change of the first capacitive proximity sensor relative to the second capacitive proximity sensor.

Non-intrusive electric power sensors for smart grid

Abstract: An electric power sensor that measures near-field voltage and current waveforms through the insulation layer on a power cord is presented. To measure the line current, we examined Hall, giant magneto-resistive (GMR) and inductive sensors and found that for sensing 60 Hz current through its magnetic field, the inductive probe resulted in the best performance. To measure the voltage waveform, we developed a near-field electric dipole antenna that consisted of two strips of copper approximately 3 mm long. The voltage and current sensors were then calibrated and uncertainties due to the placement of the sensors over power cords were determined. A method was developed to enable the power sensor to perform auto calibration to estimate miss-alignments between the sensors and the wires in the cord. Power measurement accuracy of better than 5% was achieved.

An efficient wireless power link for implanted biomedical devices via resonant inductive coupling

Abstract: This study presents a high efficiency inductive power link aiming for the implanted biomedical devices. Improving the efficiency of the inductive link is critical, since the overall efficiency of a remote powering system is dominated by the inductive link. Therefore, the proposed system utilizes the resonance phenomenon which enables maximum energy transfer between objects which are at resonance. In this study, the resonance is created between 4 spiral coils which are implemented on the internal and external units; each formed by two concentric coils. The system operates with 72% power efficiency at 10–12 MHz band at 10 mm distance which is a reasonable distance for powering implanted devices. Moreover, the characterization of the resonant inductive link with respect to distance and frequency is performed.

Inductive proximity sensor

Abstract: Present techniques provide an inductive proximity sensor having a multi-receiver coil assembly and an evaluator circuit configured to receive a differential signal from the multi-receiver coil assembly to determine the presence of a target. The multi-receiver coil assembly includes two receiver coils in a differential coil arrangement and a transmitter coil configured to emit an electromagnetic field and induce a voltage on each of the receiver coils. The voltage difference between the two receiver coils is transmitted as a differential signal to the evaluator circuit. Targets which approach the inductive proximity sensor disrupt the electromagnetic field and change the induced voltages on each of the receiver coils, thereby changing the differential signal. The evaluator circuit processes the differential signal to determine whether the changes indicate that a target is present.

Non-invasive sensing of the electrical energy harvested by medical implants powered by an ultrasonic transcutaneous energy transfer link

Abstract: Ultrasonic transcutaneous energy transfer is an effective tool for powering medical implanted devices non-invasively. The power harvested by the implanted receiver is sensitive to the distance between the transmitting and receiving transducers, and to the orientation of one with respect to the other. This work describes an inductive link as a means for the contactless measurement of the voltage generated by the ultrasonically powered implanted transducer. A closed form analytic expression of the proposed sensor is presented. The sensor was successfully simulated for an implantation depth of up to 50 mm, achieving a voltage measurement accuracy of +/− 5%. The simulation is performed by exciting an external coil attached on the skin (50 mm diameter) by an AC current source (0.01 A). The excitation frequency is swept in the range of 2–6 MHz, the peak voltage across the current-source is then measured, and the resonance frequency is correlated to the equivalent inductive link impedance.

Wire bow monitoring system for a wire saw

Abstract: A wire bow monitoring system (10) for a semiconductor wire saw device (100) is described. The wire bow monitoring system (10) includes a sensor arrangement (20) configured to be positioned adjacent to a wire (30) of the wire saw device (100), wherein the sensor arrangement (20) is adapted to detect a bow of the wire (30), wherein the sensor arrangement (20) includes at least one of an inductive sensor (22), a capacitive sensor (22) and a contact sensor (22).

Proximity sensing structure and electronic device having proximity sensing capability

Abstract: The present invention relates to a proximity sensing structure, which is disposed in an article for detecting whether an object approaches the article. The article can be an electronic device. The proximity sensing structure comprises a first sensing electrode, a wire, a second sensing electrode, and a proximity sensor. Both ends of the wire are coupled electrically to the first and second sensing electrodes, respectively. The proximity sensor is coupled electrically to the wire, the first sensing electrode, and the second sensing electrode, and detects whether the object approaches the article according to an electrical status of the wire, the first sensing electrode, and the second sensing electrode. Thereby, the proximity sensing structure according to the present invention uses the wire to increase the sensing area. In addition, the wire design makes the disposal of the proximity sensing structure more flexible.

Real-time high-precision reading algorithm for the ironless inductive position sensor

Abstract: This paper presents a novel reading algorithm for an ironless inductive position sensor which exhibits immunity to single-frequency interference (both for high and low frequency signals). This algorithm is based on the three-parameter sine fitting, whose performances have been enhanced with proper windowing function design. The proposed algorithm exhibits high precision and suitability for real-time implementation. The performances of the new algorithm are tested on simulated and measured signals and the results are discussed in detail. The algorithm has been finally tested and validated on a real-time target.

Non-ferrite structures for inductive power transfer

Abstract: An inductive power transfer apparatus suitable for producing a magnetic field for inductive power transfer is disclosed. The apparatus has three or more coils arranged such that when energised with a power source, magnetic fields produced by each coil augment each other on a first surface and substantially weaken each other on a second surface. The first and second surfaces have an obverse relationship to each other. Also disclosed is a roadway inductive power transfer module suitable for producing a magnetic field for inductive power transfer to a vehicle using the roadway, and an Inductive power transfer apparatus suitable for receiving a magnetic field for inductive power transfer.

Multi - axial induction borehole imager

Abstract: Various systems and methods are disclosed for implementing and using a multi-axial induction borehole imaging tool that includes emitters that induce, at azimuthally-spaced positions on a borehole wall, a plurality of fields having components in three non-coplanar directions within a formation The tool also includes directionally sensitive inductive sensors that sense the components caused by each of the one or more inductive emitters, and a downhole controller that processes signals received from the directionally sensitive inductive sensors to provide a set of measurements representative of an impedance tensor at each position

A magnetically coupled inductive loop sensing system for less-lane disciplined traffic

Abstract: A new multiple inductive loop detector system that uses the mutual inductances between an outer loop and multiple inner loops is presented in this paper. Automated detection, classification and speed measurement of vehicles are a challenging task in a no-lane and heterogeneous traffic. A recently reported multiple loop scheme is a solution but it is complex and less reliable due to large number of electrical connections required to realize the system. This paper proposes a loop sensor wherein small inner loops are placed within a large outer loop. In the new system the outer loop alone is connected to the measurement unit and all the inner loops are simply coupled inductively to the outer loop. This scheme is simple and can be easily employed to convert an existing single loop system to a multiple loop system by incorporating the inner loops. A suitable measurement scheme based on a synchronous detection is employed that guarantees accurate measurement. A special excitation that ensures parallel resonance of the whole inductive system is employed to keep the power consumption minimum. A prototype of the proposed system has been built and the practicality has been tested. The new system correctly sensed the vehicles, categorized and counted them in an undisciplined traffic.

Magnetic field sensor having multiple sensing elements for misalignment detection and correction in current sensing and other applications

Abstract: A sensor with multiple magnetic field sensing elements for use in current sensing and other applications is presented. The sensor includes an arrangement of two or more magnetic field sensing elements to sense magnetic field associated with a target. The sensor further includes circuitry to generate a sensor output signal based on sensing of at least one of the magnetic field sensing elements of the arrangement. Also included is a programmable misalignment adjustment block to control the circuitry to generate the output signal with compensation for misalignment between the sensor and the target. The programmable misalignment adjustment block can be programmed to select measurement of one of the two or more magnetic field sensing elements, or alternatively, a mathematical combination of measurements of the two or more magnetic field sensing elements, for generating the sensor output signal when a test of the sensor indicates a misalignment.

Implementation of vertical-integrated dual mode inductive-capacitive proximity sensor

Abstract: This study extends the authors' previous concept to employ nanoporous anodic aluminum oxide (np-AAO) as insulation and dielectric layer [1] to form the vertical-integrated inductive-capacitive proximity sensor. The advantages of this vertical-integrated inductive-capacitive proximity sensor are as follows, (1) enlarge the range of sensing distance: capacitive-sensing remains sensitive for short-distance object and long-distance object remains detectable by inductive-sensing, (2) conductive and non-conductive objects can be detected, (3) chip size is reduced by the vertical-integrated design, (4) fringe-effect is enhanced by the spiral-coil, and (5) np-AAO has good electrical properties: dielectric constant 7.4 (oxide:3.9), electrical resistivity: over hundred MΩ,-cm (similar to oxide). Preliminary fabrication results demonstrate the vertically integrated inductive-capacitive proximity sensor, and the tests show its sensing-range can reach 0.5∼5mm

Rotor study of inductive angle sensor

Abstract: Inductive angle sensor consists of the excitation coil, two receiving coils, the rotor. The sensor is based on electromagnetic induction. The structure of the sensor affects the performance of the sensor, the rotor is chosen to do the research, the rotor includes coil-rotor, hollow-rotor and solid-rotor. After performances of the sensors with different rotors using simulation are compared, the current density in coil-rotor is the lowest because of the biggest impedance among the rotors, the current density in the solid-rotor from electromagnetic induction is similar to the current density of hollow-rotor. The induced voltage of the receiving coil with hollow rotor is the biggest among different rotors, but the Adjusted R-squared of the induced voltage with solid rotor is 0.997.

Novel vehicle and motorcycle classification using single element piezoelectric sensor

Abstract: Accurate data reporting ensures suitable roadway design for safety and capacity. Currently, vehicle classifier devices employ inductive loops, piezoelectric sensors, or some combination of both to identify 13 different FHWA vehicle classifications. Systems using inductive loops have failed to accurately classify motorcycles and record relative pertinent data. Previous investigations have focused on classification techniques utilizing inductive loop signal output, magnetic sensor output with neural networks, or the fusion of several sensor outputs. This paper presents a novel vehicle classification setup that uses a single piezoelectric sensor placed diagonally across the traffic lane to accurately identify motorcycles from among other vehicles by detecting the number of vehicle tires. A vehicle classification algorithm based on number of tires detected and axle/tire spacing was formulated and deployed in an embedded system for field testing.

Device for contactless energy transmission to battery of e.g. electrically drivable vehicle, has detection device attached to primary and/or secondary coil arrangements and for monitoring intermediate space between coil arrangements

Abstract: The device has a detection device (3) attached to a primary coil arrangement (1) and/or a secondary coil arrangement (2) and for directly or indirectly monitoring an intermediate space (4) between the primary coil arrangement and secondary coil arrangement. The secondary coil arrangement is inductively coupled with the primary coil arrangement that is attached to an energy source i.e. public and/or closed electricity mains. The detection device has a sensor (5) for monitoring the intermediate space. The sensor is designed as an ultrasonic sensor, a radar sensor, an infrared (IR) sensor, an optical sensor, an inductive sensor or a capacitive sensor. An independent claim is also included for a method for operating a device for contactless energy transmission.