Abstract: A sensor element has drive vibrating arms drive-vibrating by energization, adjustment vibrating arms vibrating with the drive vibrations of the drive vibrating arms, detection electrodes outputting charge in response to physical quantities applied to the drive vibrating arms, first electrodes provided on the adjustment vibrating arms, electrically connected to the detection electrodes, and outputting charge with the vibrations of the adjustment vibrating arms, and a pair of second electrodes provided on the adjustment vibrating arms, electrically connected to a pair of detection electrodes, and outputting charge having an opposite polarity to that of the first electrodes with the vibrations of the adjustment vibrating arms.

Abstract: A surface acoustic wave device having electrodes disposed on a piezoelectric substrate, comprising a sealing member having a peripheral wall disposed on the piezoelectric substrate in surrounding relation to the electrodes, and a top plate covering the peripheral wall; and a sealing stiffener disposed on the piezoelectric substrate in facing relation to a liquid material imposed on the piezoelectric substrate and which extends parallel to a portion of the peripheral wall.

Abstract: An apparatus comprises a thin-film bulk acoustic resonator such as including an acoustic mirror, a piezoelectric region acoustically coupled to the acoustic mirror, and first and second conductors electrically coupled to the piezoelectric region. In an example, an integrated circuit substrate can include an interface circuit connected to the first and second conductors of the resonator, the integrated circuit substrate configured to mechanically support the resonator. An example can include an array of such resonators co-integrated with the interface circuit and configured to detect a mass change associated with one or more of a specified protein binding, a specified antibody-antigen coupling, a specified hybridization of a DNA oligomer, or an adsorption of specified gas molecules.

Abstract: A piezoelectric sensor comprising a piezoelectric film formed on a surface of an object to be monitored; a plurality of electrodes formed on a surface of the piezoelectric film; and wherein electrical polarization of the piezoelectric film is about coplanar with the surface of the piezoelectric film. A method of forming a piezoelectric sensor. The method comprises forming a piezoelectric film on a surface of an object to be monitored; forming electrodes on a surface of the piezoelectric film; and orientating electrical polarization in the piezoelectric film to be about coplanar with the surface of the piezoelectric film.

Abstract: To provide a piezoelectric sensor in which a first electrode for measurement and a second electrode for reference are provided apart from each other on one surface side of a piezoelectric piece and a common electrode is provided on an opposite surface side so as to face the first and second electrodes. A piezoelectric sensor includes: a first electrode for measurement and a second electrode for reference provided apart from each other on one surface side of a piezoelectric piece; a common electrode provided on an opposite surface side of the piezoelectric piece commonly for the first electrode and the second electrode to face the first electrode and the second electrode; and an adsorption layer formed on an area, of the common electrode, to which the first electrode is faced across the piezoelectric piece, to adsorb a substance to be sensed.

Abstract: MEMS in-plane resonators include a substrate wafer, at least one resonant mass supported by the substrate wafer and configured to resonate substantially in-plane, and at least one transducer coupled to the at least one resonant mass for at least one of driving and sensing in-plane movement of the at least one resonant mass, wherein at least part of one surface of the resonant mass is configured for exposure to an external environment and wherein the at least one transducer is isolated from the external environment. Such MEMS in-plane resonators may be fabricated using conventional surface micromachining techniques and high-volume wafer fabrication processes and may be configured for liquid applications (e.g., viscometry, densitometry, chemical/biological sensing), gas sensing (e.g., where a polymer film is added to the sensor surface, further degrading the damping performance), or other applications.

Abstract: Field devices for measuring a pressure or a fill level are connected, by way of a cable connection or a radio connection, to stationary evaluation- and display devices. To provide flexible parameterization or flexible measured-value inquiry, a connection box for the wireless transmission of signals between the field device and the control device is stated, which connection box comprises an interface connection and a radio interface. For the purpose of transmitting the signals, the interface connection and the radio interface are coupled to each other so as to be able to communicate.

Abstract: A piezoelectric sensor having a plurality of electrodes deposited on a single surface of the dielectric medium is generally provided. The plurality of electrodes can define a plurality of square-shaped electrodes forming a grid on the first surface of the dielectric medium while the second electrode defines a continuous electrode. An electrode border surrounding the plurality of electrodes can be deposited on the first surface of the dielectric medium. Alternatively, the plurality of electrodes can define column-shaped electrodes, while the second electrode defines a plurality of row-shaped electrodes separated by etchings. The direction of orientation of each column-shaped electrode and the direction of orientation of each row-shaped electrode can be substantially perpendicular. A method of making a piezoelectric sensor is also provided.

Abstract: A smart material actuator comprising a mechanical amplifier with a fixed supporting member, at least one mountable actuating arm, and mechanical web having at least one compliant member attached to the mountable arm and a movable supporting member. A piezoelectric stack is affixed between a first mounting surface on the fixed supporting member and a second mounting surface on the movable supporting member. With the fixed supporting member being substantially rigid, and the piezoelectric stack being affixed between the first mounting surface and the second mounting surface, which are substantially parallel, applying an appropriate electric potential to the piezoelectric stack will cause it to expand substantially without angular movement. The expansion urges the second mounting surface away from the first, thereby causing the compliant members of the mechanical web to flex, thereby moving the mountable actuating arm.

Abstract: A microresonator for use as a resonator in a detector is disclosed. In one aspect, the microresonator has a first predetermined resonance mode. The microresonator has an integrated electronic transducer for measuring deformation of the microresonator in the first predetermined resonance mode of the microresonator. The transducer is located at a local deformation of the predetermined resonance mode to measure the deformation of the microresonator at such location. The first predetermined resonance mode may be one of higher order resonance modes.

Abstract: An ultrasonic sensor, in particular for a vehicle, including a housing, includes the following: a transducer element which is attached to the bottom of the housing for generating ultrasonic oscillations; a first damping element situated in the housing for damping oscillations of the bottom; and a cover for sealing the housing, the cover being provided with a second damping element and having continuous tapering of the cover thickness in the region of the second damping element.

Abstract: A sensor includes a film, at least one piezoelectric strip disposed on the film, a first conductive line disposed on the film, the first conductive line electrically connected to a first portion of the at least one piezoelectric strip, a second conductive line disposed on the film, the second conductive line electrically connected to a second portion of the at least one piezoelectric strip, and a dampening member disposed on the at least one piezoelectric strip.

Abstract: A piezoelectric element includes a support body having a displacing part capable of undergoing displacement, a lower electrode layer having a lower main electrode body and a lower electrode wire part with the lower main electrode body being formed on the support body and provided within the displacing part in a plan view and the lower electrode wire part being connected to the lower main electrode body and provided across an interior and an exterior of the displacing part, a first piezoelectric layer provided on the lower main electrode body, an upper electrode layer provided across the interior and exterior of the displacing part with at least a part of the upper electrode layer being layered on the first piezoelectric layer and insulated from the lower electrode layer, and a second piezoelectric layer provided on the support body to cover at least a part of the lower electrode wire part.

Abstract: The disclosure may relate to example embodiments of an electronic tongue sensor that may include an array of piezoelectric quartz crystal sensors with at least one coating specific for sensing a specific taste-producing molecule. In an example embodiment, a coating may include molecularly imprinted polymers of a specific taste-producing molecule.

Abstract: A resonator element includes: a base part; plural vibrating arms extended from the base part, each having a first principal surface and a second principal surface opposed to each other and a first side surface and a second side surface connecting the first principal surface and the second principal surface and opposed to each other, the first side surface of at least one vibrating arm of the plural vibrating arms having a first step part provided from the first principal surface side and a second step part provided from the second principal surface side; a first electrode provided on the second side surface of the vibrating arm; a second electrode provided in a position opposed to the first electrode of the first step part; and a third electrode provided in a position opposed to the first electrode of the second step part.

Abstract: A piezoelectric cantilever sensor includes a piezoelectric layer and a non-piezoelectric layer, a portion of which is attached to the piezoelectric layer. In one embodiment, one end of the non-piezoelectric layer extends beyond the end of piezoelectric layer to provide an overhang. The overhang piezoelectric cantilever sensor enables increased sensitivity allowing application of the device in more viscous environments, such as liquid media, as well as application in liquid media at higher flow rates than conventional piezoelectric cantilevers. In another embodiment, the sensor includes first and second bases and at least one of the piezoelectric layer and the non-piezoelectric layer is affixed to each of the first and second bases to form the piezoelectric cantilever sensor. In this embodiment, the sensor is robust and exhibits excellent sensing characteristics in both gaseous and liquid media, even when subjected to relatively high flow rates.

Abstract: An acoustic wave resonator device comprising a resonant layer that comprises a series of side-by-side areas of first and second dielectric materials. In one embodiment the first dielectric material is a piezoelectric, in particular the first dielectric material can be a piezoelectric and the second dielectric material can be non-piezoelectric. In another embodiment, the first dielectric material is a piezoelectric of first polarity and the second dielectric material is a piezoelectric of opposite polarity or different polarity. Where needed, the resonant layer is supported on a reflector composed of series of layers of high acoustic impedance material(s) alternating with layers of low acoustic impedance material(s). For example, the reflector comprises AlN, Al2O3, Ta2O5, HfO2 or W as high impedance material and SiO2 as low impedance material.

Abstract: In an arrangement of at least one piezoacoustic resonator on a substrate surface, the resonator has an piezoelectric layer, an electrode and a further electrode arranged such that activation of the electrodes leads to a resonance oscillation, the substrate surface is formed by an acoustic mirror integrated in the substrate for acoustically insulating substrate and resonator, and with a resonance frequency evaluation device being connected to the electrodes by tracks being routed through a mirror opening. The acoustic mirror has a Bragg reflector having ?/4-thick layers of different acoustic impedance. The topmost layer is made of silicon dioxide acting as an insulation layer in the mirror opening for electrically insulating the conductor track and the electrically conductive Bragg reflector layers. The arrangement is used as a physical transducer of a device for detecting a substance of a fluid, in particular of a fluid in the form of a liquid (biosensor).

Abstract: Disclosed is a piezoelectric/electrostrictive membrane sensor wherein the main component of terminal electrodes is contained in the vicinity of the surface of a piezoelectric/electrostrictive body. The membrane sensor is hardly electrostatically charged and thus prevented from electrostatic discharge damage and/or the attraction of dust, dirt or the like.

Abstract: A piezoelectric/electrostrictive membrane type sensor is provided with a ceramic base body and a piezoelectric/electrostrictive element. The ceramic base body includes a thin diaphragm portion, a thick portion and a cavity formed by the portions. The piezoelectric/electrostrictive element is arranged on the ceramic base body and also includes a piezoelectric/electrostrictive body, and an upper electrode and a lower electrode sandwiching the piezoelectric/electrostrictive body. Further, the piezoelectric/electrostrictive body contains an alkaline metal or an alkaline earth metal, with the upper electrode and the lower electrode containing gold or platinum. When there is a change in the atmosphere at a place where the sensor is used, the sensor copes with such change and at least prevents the continuation of a low-quality measurement.

Abstract: Provided is a transducer having first and second surfaces including first electrode lines positioned along the first surface in a first direction and configured for grounding and second electrode lines positioned along the second surface in a direction orthogonal to the first direction. The second electrode lines are configured switching between receiving and transmitting in an interlaced manner.

Abstract: A surface acoustic wave device having electrodes disposed on a piezoelectric substrate, comprising a sealing member having a peripheral wall disposed on the piezoelectric substrate in surrounding relation to the electrodes, and a top plate covering the peripheral wall; and a sealing stiffener disposed on the piezoelectric substrate in facing relation to a liquid material imposed on the piezoelectric substrate and which extends parallel to a portion of the peripheral wall.

Abstract: A pressure detection unit includes: a first piezoelectric resonator element having a vibrating portion and a pair of base portions connected to both ends of the vibrating portion; a second piezoelectric resonator element having a resonating arm and a base portion integrated with one end of the resonating arm; a diaphragm having a pair of supporting portions to which the base portions of the first piezoelectric resonator element are bonded; and a base disposed to be opposed to the diaphragm. In the pressure detection unit, the base portion of the second piezoelectric resonator element is joined to one of the base portions of the first piezoelectric resonator element in an identical plane.

Abstract: An integrated MEMS and IC system (MEMSIC), as well as related methods, are described herein. According to some embodiments, a mechanical resonating structure is coupled to an electrical circuit (e.g., field-effect transistor). For example, the mechanical resonating structure may be coupled to a gate of a transistor. In some cases, the mechanical resonating structure and electrical circuit may be fabricated on the same substrate (e.g., Silicon (Si) and/or Silicon-on-Insulator (SOW and may be proximate to one another.

Abstract: A resolver stator portion is attached to a resolver stator portion side attaching portion formed at a position facing to a resolver rotor portion via an elastic ring. Thus, it is possible to absorb a dimensional error of the resolver stator portion side attaching portion on the basis of an elastic deformation of the elastic ring even in the case that the dimensional error is generated in the resolver stator portion side attaching portion.

Abstract: The invention relates to piezoelectric sensor arrangements, especially sensor arrangements that can be operated in a measuring fluid, in order to be able to detect, for example, elastic properties of the measuring fluid itself or the presence and/or concentration of analyte molecules in the fluid. According to the invention, the sensor arrangement comprises an acoustic resonator which has a sensitive region and is arranged such that a resonance frequency of the sensor arrangement varies according to properties of the measuring fluid. The acoustic resonator is formed by a piezoelectric thin layer resonator and the sensitive region is produced by means of epitaxy, such that transversally polarised vibration modes can be induced.

Abstract: A sensor is provided for the detection of a marker in a sample in which the sensor includes a high frequency 500 kHz-1 GHz piezoelectric ceramic resonator, with the system measuring resonant frequency change. In one embodiment, the piezoelectric sensor operates in the thickness extensional (TE) mode, with the high frequency and TE mode permitting fabrication of an exceptionally small size sensor capable of being arrayed in a handheld unit.

Abstract: Device for converting mechanical energy from the impact of objects into electrical energy, comprising a frame, a membrane suspended on said frame by at least a first and second longitudinal end, said membrane being intended to be impacted by said objects in a direction substantially transverse to a mid-plane of the membrane, said membrane comprising a core made from material for transducing mechanical energy into electrical energy, extending from the first longitudinal end to the second longitudinal end, and at least one electrode on a first face of the core and at least one electrode on a second face of the core, said electrodes extending from the first to the second longitudinal end.

Abstract: A coating providing high abrasion and chemical resistance composed of a barrier layer from vanadium, molybdenum, niobium, tantalum and the like, and an outer layer of diamond-like carbon. The coating is especially applicable for acoustic wave device (AWD) based sensors, and for passivating an electrode such as an electrode deposited on the AWD sensing area. The coating provides excellent mechanical and acoustical characteristics for coating acoustic wave devices allowing the sensor to operate in harsh environments.

Abstract: A piezoelectric bimorph cantilever is used for determining physical parameters in a gaseous or liquid environment. The sensor works as a driven and damped oscillator. Contrary to common cantilever sensor systems, the piezoelectric film of the bimorph cantilever acts as both a sensor and an actuator. Using at least two resonance mode of the bimorph cantilever, at least two physical parameters can be measured simultaneously in a gas or a liquid. An optimized piezoelectric cantilever and a method to produce the cantilever are also described.

Abstract: The present invention discloses a physical/biochemical sensor using a multisized piezoelectric microcantilever resonator array which enables to quantitatively and simultaneously analyze a mass loading effect and a surface stress change effect and a manufacturing method thereof. In the physical/biochemical sensor using the multisized piezoelectric microcantilever resonator array, a plurality of piezoelectric micro-cantilever resonators having different sizes is arrayed so as to quantitatively and discriminately analyze a surface stress change as well as a sensor surface mass change induced by an adsorbed sensing-target material occurring in a sensing process. Thus, the mass loading effect and the surface stress change effect can be quantitatively and simultaneously analyzed.

Abstract: A sensing instrument includes: a reference sensor including a reference piezoelectric resonator not adsorbing a substance to be sensed; a reference oscillator circuit oscillating the reference piezoelectric resonator; a measuring unit receiving an oscillation output of a sensing oscillator circuit and an oscillation output of the reference oscillator circuit in a time-series manner to measure frequencies of the oscillation outputs of the oscillator circuits; and a data creator creating time-series data of a difference between a frequency in a sensing sensor and a frequency in the reference sensor, based on the frequencies of the oscillation outputs of the oscillator circuits obtained by the measuring unit. Therefore, a frequency changed due to a factor other than the adsorption of the substance to be sensed is cancelled.

Abstract: An electromechanical motor, comprising a stator, including a drive unit and a frame portion, the frame portion holding the drive unit. The motor includes a shuttle adapted to be moved relative to the stator in a displacement direction, the shuttle movement being controlled by the drive unit and where the drive unit comprises at least one electromechanical drive element, extending along said displacement direction, and a drive body adapted to transfer a movement of the drive element onto the shuttle. The motor includes a sensor connected to the drive element and adapted to sense an electric or magnetic signal generated by the drive element in response to mechanical stress being applied to the drive element and to output a sensor signal.

Abstract: Embodiments of an electronic tongue sensor, as well as test results, are discussed.

Abstract: An ultrasonic motor that is capable of stable driving by preventing uneven rotation of a driven body and maintaining the drive efficiency is provided. The ultrasonic motor includes a plurality of ultrasonic transducers including alternately stacked first piezoelectric elements and second piezoelectric elements, and a control unit for applying the same two-phase driving AC voltages to the plurality of ultrasonic transducers. The ultrasonic motor simultaneously generates longitudinal vibration and flexural vibration at the ultrasonic transducers to generate substantially elliptic vibration at output ends of the ultrasonic transducers and relatively moves the ultrasonic transducers and a driven body in contact with the ultrasonic transducers.

Abstract: The invention provides an ultrasonic motor including internal electrodes provided in an ultrasonic vibrator and disposed in regions where electrical charges of the same sign are generated in one vibration mode and where electrical charges of opposite sign and substantially the same amount are generated in another vibration mode; and a control unit configured to detect a phase difference between a vibration detection signal detected on the basis of electrical signals from the internal electrodes and any one of driving AC voltages, and to set a driving frequency such that the phase difference becomes a reference phase difference. Each driving AC voltage with the driving frequency set by the control unit is applied to the ultrasonic vibrator.

Abstract: The present invention prevents instability of frequency measurement caused by spatial connection between quartz sensors adjacent to each other when a plurality of quartz sensors, including a quartz resonator which varies a national frequency due to adsorption of an object, are to be detected. A common measuring unit measures a variation in frequency of each oscillation circuit corresponding to each quartz sensor by switching and connection in turn, and the oscillation circuits, excepting an oscillation circuit connected to the measuring unit by switches, are connected to a load on the output side of the oscillation circuit channels connected to the measuring unit and the load value is such that the respective oscillating frequencies are forcibly separated from each other.

Abstract: An air pressure sensor capable of measuring air pressure highly accurately with a simple configuration is provided. The sensor includes: a sealed case with a sealed space formed therein; a first thin plate member which constitutes at least a part of the wall of the sealed case and deforms to allow the capacity of the sealed space to vary corresponding to changes in the outside air pressure; a first PZT which contacts the first thin plate member to thereby detect the natural frequency thereof; and a second thin plate member which has the same vibration characteristics as those of the first thin plate member and is provided outside the sealed case while contacting it; and a second PZT which has the same temperature characteristics as those of the first PZT and contacts the second thin plate member to thereby detect the natural frequency thereof.

Abstract: An object of the present invention is to perform measuring work easily when detecting the presence or absence of an object to be measured or the concentration thereof using a plurality of quartz sensors equipped with a Langevin type quartz resonator. As a concrete means for solving the problem, a quartz sensor 3 equipped with a quartz resonator 30 forming an adsorbing layer to adsorb a target component to be measured on one surface side and coming into contact with an airtight space on the other surface side is installed in a printed circuit board 4 via a base 5. A plurality of quartz sensors 3 is detachably installed respectively in a plurality of connecting terminal units provided in a horizontal arrangement on a side surface 21 of the measuring device main unit 2 via a connecting terminal unit 41 formed on an end of the printed circuit board 4 in a state that the above-described adsorbing layer faces upward.

Abstract: A surface acoustic wave sensor which incorporates: a) a first layered SAW device consisting of a piezoelectric crystal such as lithium niobate or lithium tantalate with interdigital electrodes on its surface, and second piezoelectric layer such as zinc oxide over said interdigital electrodes b) a second layered SAW device consisting of a piezoelectric crystal with interdigital electrodes on its surface, a second piezoelectric layer over said interdigital electrodes and an analyte sensitive surface such as gold on said second piezoelectric layer c) both saw devices are fabricated on the same substrate d) reflectors are located adjacent the interdigital electrodes in each saw device to reduce the bandwidth of the device e) the resonator circuits of each saw sensor incorporate amplifiers which are dependent.

Abstract: A longitudinally driven slotted transducer has a tubular member with an axial slot extending from one end to the other end. A drive assembly is disposed across the inner wall of the tubular member and supported by journal bearing surfaces extending from opposing sides of the inner wall to locate the drive assembly in a position offset from the longitudinal central axis of the tubular member. The interface between the drive assembly and tubular member comprises a layer of solid lubricant material mounted on the journal bearing type surfaces.

Abstract: An ultrasonic wave generating device includes a substrate, a heat insulation layer on the substrate, a membrane heating portion on the heat insulation layer, and a membrane oscillator on the heating portion. The heating portion is electrically driven with a predetermined period, and produces heat for thermally displacing a surface of the oscillator. The oscillator receives a temperature variation with the predetermined period from the heating portion, and oscillates so as to generate ultrasonic waves.

Abstract: An object of the present invention is to perform measuring work easily when detecting the presence or absence of an object to be measured or the concentration thereof using a plurality of quartz sensors equipped with a Langevin type quartz resonator. As a concrete means for solving the problem, a quartz sensor 3 equipped with a quartz resonator 30 forming an adsorbing layer to adsorb a target component to be measured on one surface side and coming into contact with an airtight space on the other surface side is installed in a printed circuit board 4 via a base 5. A plurality of quartz sensors 3 is detachably installed respectively in a plurality of connecting terminal units provided in a horizontal arrangement on a side surface 21 of the measuring device main unit 2 via a connecting terminal unit 41 formed on an end of the printed circuit board 4 in a state that the above-described adsorbing layer faces upward.

Abstract: A sensor unit for picking up mechanical vibrations, sound and ultrasound has at least one piezoelectric foil strip (piezo strip) as a sensor element. The piezo strip has signal wires attached thereto for transporting out electrical signals representing vibration, sound or ultrasound that have been picked up. The piezo strip is, at two opposite ends, attached to flat support parts, and at least one engagement strip of for instance plastic material is attached in the same support parts to extend in curved-out fashion along the piezo strip, thereby to provide at least one space between the strips. Several sensor units can be mounted together in a frame to constitute a sheet with a sensor matrix.

Abstract: An air pressure sensor capable of measuring air pressure highly accurately with a simple configuration is provided. The sensor includes: a sealed case with a sealed space formed therein; a first thin plate member which constitutes at least a part of the wall of the sealed case and deforms to allow the capacity of the sealed space to vary corresponding to changes in the outside air pressure; a first PZT which contacts the first thin plate member to thereby detect the natural frequency thereof; and a second thin plate member which has the same vibration characteristics as those of the first thin plate member and is provided outside the sealed case while contacting it; and a second PZT which has the same temperature characteristics as those of the first PZT and contacts the second thin plate member to thereby detect the natural frequency thereof.

Abstract: A micro device may comprise a substrate, a first micro structure coupled to the substrate, a second micro structure coupled to the substrate, and port configured to receive an input. The first micro structure is configured to move into engagement with the second micro structure in response to the input.

Abstract: A micro drive assembly may comprise a substrate, a micro shall oriented in-plane with the substrate and at least one micro bearing to support rotation of the micro shaft. The micro shaft and micro bearing may be in or less than the micrometer domain.

Abstract: The invention concerns an ultrasonic transducer, which is assembled from several parts. These parts are a protecting plate, a piezoelectric disc and a housing. Joining of the parts for transducers are normally done by means of TIG welding or laser welding, but these are relatively costly processes, which also has an impact on the transducer, especially the piezoelectric disc, due to the heat. In order to reduce the heat load and simultaneously simplify manufacturing an ultrasonic transducer is suggested, in which the protecting plate and the housing consists of electrically conducting materials of different kinds and where joining of housing and plate is done by using a mechanical force influence and an electrical current which flows through plate and housing. Also, a method for joining the parts of an ultrasonic transducer is described.

Abstract: An analytical apparatus, such as a quartz crystal microbalance, comprises a piezoelectric sensor and an oscillator circuit, coupled to the sensor, to oscillate at a frequency substantially determined by a resonant frequency of the sensor, and to provide an output signal at the oscillator frequency at an output. The oscillator circuit maintains a substantially constant drive signal to the piezoelectric sensor by an AGC (33) within a feedback loop of the oscillator. The gain control signal is used as an indication of the Q of the piezoelectric sensor. The drive signal to the sensor is made substantially sinusoidal by ensuring that all the elements in the feedback loop providing signal gain and attenuation are configured to operate in a substantially linear mode.

Abstract: The present invention provides a method and system for stabilizing a rotor about its geometric center in a magnetic bearing system at a constant rotor speed. In the method, the controller for controlling the magnetic bearing uses an adaptive control algorithm which simultaneously identifies and compensates for synchronous sensor runout and rotor mass unbalance while determining a control action that drives the rotor rotating at a constant speed to its geometric center. The identification of sensor runout and mass unbalance is by varying the magnetic stiffness which is achieved by perturbation of the bias currents in opposing electromagnet coils in a manner that does not alter the equilibrium of the rotor while it is rotating at a constant speed.