87 results about "Piezoelectric accelerometer" patented technology

A finger-mounted implement including a kinesthetic sensor, at least one tactile sensor, and means for securing the kinesthetic sensor and the at least one tactile sensor to a fingertip. The tactile sensor may be a thin-film force transducer, a piezoelectric accelerometer, or a combination thereof. An artificial fingernail may be connected to the accelerometer. The kinesthetic sensor may include a magnetic transducer and may sense an X-Y-Z position and an angular orientation of a fingertip to which the kinesthetic sensor is secured. The securing means may include at least one means selected from the group consisting of adhesive tape, an elastically deformable cover, and detachable adhesive. The implement can be further connected to a computer processing system for, amongst other things, the virtual representation of sensed objects. The implement can also be used as part of a method of haptic sensing of objects.

The invention provides an engineering nonlinear vibration inspection method. The method adopts a wavelet nonlinear threshold value filtering wave to filter wide-frequency background noise of a three-direction acceleration signal and to remove DC bias so as to get the treated acceleration signals after frequency domain filtering and removal of trend term. Then speed signals and displacement signals are obtained after the acceleration signals is subject to a first time and second time integrals and removal of trend term. The characteristics and types of the nonlinear vibration are determined through a three-dimensional phase space diagram and other calculations of a reconstructed phase space tested by the three-dimensional phase space diagram. The invention adopts three-direction low resistance piezoelectricity acceleration meter to measure the vibration accelerations of three orthogonal directions. The invention has convenient installation, easy usage and reliable analysis, overcomes the problems of drifting, delay and aberration of the actual acceleration signals after passing through analog integration or digital integration. The invention plays an important role in the engineering nonlinear vibration inspection for mechanical mechanisms, bridges, dams and buildings, etc.

The invention discloses a method for diagnosing mechanical states of a distribution switch on the basis of empirical mode decomposition (EMD) sample entropy and fuzzy c-means clustering (FCM). The method comprises the following steps that a piezoelectric accelerometer is mounted near to a main shaft of a switch operating mechanism, and the vibration signals of the distribution switch of different mechanical states at the off and on moments are collected through a data acquisition card and a waveform display storage platform; EMD time frequency decomposition is carried out on the collected vibration signals to obtain the limited number of intrinsic mode components of different frequency and unequal bandwidths and residual error components; the sample entropies of intrinsic mode functions (IMFs) of all orders of the vibration signals of different mechanical states are calculated, and a sample entropy array is formed as the characteristic quantity of the mechanical states of the distribution switch; the sample entropy array is used as the input of the FCM, and the mechanical states of the distribution switch are diagnosed through a fuzzy clustering method.

A method of generating an enhanced receive signal from a piezoelectric ultrasound transducer is described. The method comprises providing a piezoelectric ultrasound transducer comprising a piezoelectric element operable in flexural mode, receiving a acoustic signal by the piezoelectric element, applying a DC bias to the piezoelectric element prior to receiving the acoustic signal and / or concurrently with receiving the acoustic signal, and generating an enhanced receive signal from the piezoelectric element as a result of receiving the acoustic signal by the piezoelectric element. pMUT-based imaging probes using the above method are also described.

The invention provides a three-axis intermediate-frequency vibration standard device comprising a three-axis intermediate-frequency standard vibration stand, a vibration control system and a three-axis laser vibration measuring system. The three-axis intermediate-frequency standard vibration stand consists of a pedestal platform, an X-axis vibration table, a Y-axis vibration table, a Z-axis vibration table, an integrated vibration generator, a working table and a trapezoidal support seat. The vibration control system includes a computer control system, a six-path vibration controlling instrument, a three-axis power amplifier, a three axial piezoelectric accelerometer, a charge amplifier and an automatic centering device. The three-axis laser vibration measuring system consists of a three-axis laser vibration measuring instrument, a target and a three-axis laser vibration measuring instrument mounting bracket. With the three-axis intermediate-frequency vibration standard device, one-time synchronous measuring or calibration of sensitivity of the three axial piezoelectric accelerometer can be realized; the measuring / calibrating state of the three axial piezoelectric accelerometer conforms to the working state of the three axial piezoelectric accelerometer; and accuracy and reliability of the sensitivity measuring value are improved.

This invention is for a hermetic piezoelectric accelerometer sensor that can operates at high temperatures without the degradation observed on the piezoelectric elements, due to Oxygen depletion of the piezoelectric materials, when they are exposed to high temperatures, in reducing atmospheres, or low partial Oxygen pressure, inside a sealed housing. When a piezoelectric element loses Oxygen, becomes more electrically conductive, and this severe loss in resistivity, exacerbated with the increase of the temperature, makes the sensor inoperable, unreliable, or with permanent damage. The accelerometer of this invention operates effectively over a wide range of temperatures, including high temperatures above 1600° F., depending of the piezoelectric element used on the construction. The housing of the accelerometer uses a small section of metal made with Silver (or Silver alloys) to allow Oxygen diffusion through the metal, when it is exposed to high temperature. This permits that the construction of the accelerometer housing, can be sealed hermetically; and the piezoelectric elements of the sensor have increased lifetime, with enough partial pressure of Oxygen inside the housing.

An automotive brake light system producing a graduated display according to the level of vehicle deceleration as sensed by an onboard piezoelectric accelerometer. Taillight assemblies are divided into segments which are illuminated in sequence to produce a graduated display. The vehicle anti-lock brake system may be connected into the system to provide a special lighting effect such as blinking the taillights during a panic stop condition.

The miniaturized piezoelectric accelerometer includes a support frame (102) having a cavity (104) and a seismic mass (108) supported by a plurality of suspension beams (110) extending from the support frame (102). Each of the suspension beams (110) has a piezoelectric thin film coated on a top surface thereof, with a pair of inter-digital electrodes (114) deposited on an upper surface of each piezoelectric thin film. The presence of acceleration excites bending and thus strain in the piezoelectric thin film, which in turn causes electrical signals to be generated over terminals of the electrodes (114). To collect constructively the output of the electrodes (114), one terminal of each of the electrodes (114) is routed to and electrically connected at a top surface (308) of the seismic mass (108).

The invention discloses a piezoelectric transduction type magnetostrictive sensor used for liquid level (displacement) measurement and a piezoelectric type torsional wave transducer thereof. The piezoelectric type torsional wave transducer comprises a waveguide wire, the output section of the waveguide wire is provided with an amplification rod, and the ends of the amplification rod are connectedwith piezoelectric elements. After a torsional wave signal is transmitted to the amplification rod through the waveguide wire and is amplified, the torsional wave signal is converted into an electricsignal and output. A normal line of each piezoelectric element is vertical to the waveguide wire and the amplification rod. The amplification rod converts circumferential torsional waves transmitted by the waveguide wire into distortion approximate to a linear direction on the normal line of each piezoelectric element so as to act on the piezoelectric elements to generate charges. Two ends of theamplification rod are respectively provided with the piezoelectric elements with same polar directions, and the piezoelectric elements can simultaneously generate differential piezoelectric signals. The piezoelectric type torsional wave transducer has the advantages that the commonly-used piezoelectric ceramic plates of a thickness oscillating mode are used as the piezoelectric elements, thus thecost is low; the transducer has simple structure and simplified process; and the piezoelectric elements can be used for directly converting mechanical signals into voltage signals, thus the advantages of fewer links and high sensitivity are achieved.

The sheared bottom-insulated piezoelectric accelerometer, capable of using at high temperature of 200 deg.C is characterized by that its piezoelectric sensing element is a modified lead metanibate high-temp. piezoelectric ceramics made up by using Ca (2+) or Ba (2+) and adding rare-earth oxide. At the same time it adopts a high specific weight elconite mass block, and uses glass body as insulating material of signal output device instead of fluoroplastics, and can uses polyimide material which can be used at 200-250 deg.C for a long period and possesses high impedance and good abrasive resistance to make insulator, and the internal cavity of insulator can be any one kind of inner hexagon, tetragonal or star form. It adopts screw and epoxy resin adhesive double connection process to fix said insulator to the base seat to the accelerometer.

The invention relates to a friction vibration test device and a test method thereof. The test device comprises a base. A motor, a to-be-tested gear reducer and a hydraulic dynamometer are arranged on the central axis of the upper end face of the base in sequence. The output shaft of the motor is connected with the input shaft of the to-be-tested gear reducer through a coupling. The output shaft of the to-be-tested gear reducer is connected with the spindle of the hydraulic dynamometer through a coupling. A piezoelectric acceleration sensor is fixedly arranged on the to-be-tested gear reducer. The test method combines friction test, wear test and vibration test. After multiple sets of information are fused, a new integrated state index is obtained, which is used as the basis of next step of state identification.

The invention provides a 3D co-vibration spherical vector hydrophone with an asymmetrical structure which includes an upper half spherical shell, a lower half spherical shell, an output cable and a core vibrator; the core vibrator consists of three piezoelectric accelerometers which are asymmetrically arranged on a central mass block; the core vibrator is arranged in a supporting flange; the supporting flange is clamped between the upper half spherical shell and the lower half spherical shell by a bolt and a seal ring. The quantities of the internal piezoelectric accelerometers needed by the hydrophone of the invention are less, the integral average density is low and the physical dimension is small; besides, the internal piezoelectric accelerometers have better cosine directivity and phase characteristics. Therefore, the low-frequency vector hydrophone not only has the advantages of small size, light weight and good directivity, but also has the advantages of good channel sensitivity and phase characteristics; the hydrophone can solve the design problem of a sonar array. The 3D co-vibration spherical vector hydrophone with the asymmetrical structure can be broadly applied into each field of underwater sound like a sonobuoy system, a low noise measuring system, a double-base sonar system, a torpedoe navigation system, an underwater communication system, a responder, and the like, to accomplish a lower frequency measuring task.

The invention discloses an aeroengine vibration transducer double-wire checking and detecting method and an implementation system thereof. The implementation system comprises a main system which is formed by a computer, a controller, a power amplifier, a power supply, a vibration table, a vibration measuring instrument, a digital display No.1 and a piezoelectric accelerator No.1, and an auxiliary system which is formed by a piezoelectric accelerator No. 2, a charge amplifier and a digital display No.2 and is used for detecting the self errors of a vibration system. The checking and detecting method comprises that a computer is used to build a vibration test, the checking and detecting main system detects and displays the vibration signal which is detected by a detected vibration transducer, the auxiliary system detects the self errors of the vibration system, and the detected vibration transducer is checked and detected through eliminating the self errors of the detecting vibration system. By utilizing the method, the problems that a single-wire checking and detecting method of the prior art cannot reflect the vibration system error elimination, cannot correctly judge the detected vibration transducer and the like are solved, and the method has the characteristics of high checking accuracy, high working efficiency and the like.

The present invention provides a piezoelectric accelerometer. The sensitive components are arranged axisymmetrically; the piezoelectric accelerometer comprises four flexible arms, a quality block and a base; the flexible arms are folded and shaped like a ring or an arc; any two of the flexible arms are arranged opposite to the other two so as to form an orthogonal annular symmetric structure which connects the quality block and the base; and the flexible arms are made of piezoelectric material or the piezoelectric sheets are symmetrically pasted on the flexible arms. The accelerometer can perform the three-axis measurement, and because of the structural symmetry, when the axial acceleration is measured, the response of the transverse acceleration can be reduced; when the transverse acceleration is measured, the response of the axial acceleration can be reduced; therefore, the interference between the channels is inhibited to the lowest degree. The three-way accelerometer has the characteristics of high sensitivity, small transverse interference and simple manufacturing process, and can be used in the industrial production, the scientific research and the national defense field.

The invention discloses a small active vibration control system based on piezoelectric ceramic and a piezoelectric accelerometer, and relates to the technical field of precision machineries and modern control. The system comprises a micro-vibration source (00), a sensor (10), an acceleration module (20), a displacement module (30), a speed module (40), a first summator (50), an amplifying and filtering module (60), a second summator (70), a driving module (80) and the piezoelectric ceramic. The small active vibration control system has the advantages of simple structure, small size and easiness in integration, and can obtain a wider control band width, wherein the control frequency can achieve 200 Hz or even higher; the electric damping is adopted to replace mechanical damping, so that the realization is simpler; and a displacement signal is adopted as low-frequency drift compensation instead of adopting a method of direct current feedback to execute direct current stability, so that enough low-frequency gain and phase margin are guaranteed, and the control band width and the suppression ratio are effectively improved.

The invention discloses a system and method for online measurement of vibration of a solid rocket engine, and relates to the field of machining manufacture and optical measurement. The system performs measurement by employing a measuring module formed by a camera obscura and a blocking piece, the inner part of the camera obscura includes a light emitting diode array, a lamp box, and a linear array CCD sensor, different light-emitting brightnesses can be obtained through adjustment of the current of the light emitting diodes, the front surface of the lamp box is provided with a vertical slit, light emitted by the light emitting diode array can be changed to linearly polarized light through the vertical slit, the linear array CCD sensor is used for receiving the light emitted by the lamp box, and the goal of online measurement is finally achieved by optical signals received by the linear array CCD sensor. According to the system and method, inevitable defects of many conventional piezoelectric accelerometers are overcome, the measuring precision is radically improved, and the measuring efficiency is improved.

The invention discloses a three-axis piezoelectric accelerometer, and relates to accelerometers. According to the three-axis piezoelectric accelerometer, the sensitivity of the accelerometer can be improved, and the frequency bandwidth of the accelerometer is increased. The three-axis piezoelectric accelerometer is provided with a weight block which is an octolateral cylinder. A left beam, a right beam, a front beam and a rear beam are arranged on two symmetrical edges of the weight block, and all the beams are in a cuboid shape. Four piezoelectric patches are symmetrically distributed on the upper surface of the left beam, four piezoelectric patches are symmetrically distributed on the upper surface of the right beam, four piezoelectric patches are symmetrically distributed on the upper surface of the front beam, four piezoelectric patches are symmetrically distributed on the upper surface of the rear beam, and metal electrodes are arranged above and below each piezoelectric patch. The weight block, the left beam, the right beam, the front beam and the rear beam are of an integrated structure.

Provided is a method for converting a PR9270 type vibration exciter into a piezoelectric accelerometer calibrator. Through the method that two supporting bearings of the PR9270 type vibration exciter are reversely arranged, an adjusting vibrating spring is further arranged, and a set of vibrating table board (or a cantilever beam) is arranged at the top end of a shaft rod, and peripheral detection equipment, the vibration exciter is remanufactured into the piezoelectric accelerometer calibrator. Through the method, measurement precession can reach 4%, and convenience, practicality and economic performance are achieved. Meanwhile, the calibrator can be restored to the vibration exciter.

The invention provides a remote transmission IEPE type charge amplifier which comprises the charge amplifier and an IEPE interface circuit. The remote transmission IEPE type charge amplifier is characterized in that the charge amplifier is composed of a charge feedback condenser C1 and an operational amplifier A, the charge feedback condenser C1 is connected to the two ends of the operational amplifier A in parallel, a capacitor C2 and a field-effect transistor are connected with each other in series and then are connected with a capacitor C3 in parallel to form the IEPE interface switching circuit of a piezoelectric accelerometer, the sum of the distributed capacitance Cd of an input cable of the IEPE type charge amplifier and the capacitance Ca which inputs to the piezoelectric accelerometer is equal to Ct, transmission gain is adjusted by means of the feedback effect of the C1, the output negative feedback voltage VO is equal to Q / C1, and Q represents the output charge of the piezoelectric accelerometer. By means of the remote transmission IEPE type charge amplifier, charge and voltage conversion, impedance conversion, gain amplification are conducted on the charge signals output by the piezoelectric accelerometer, the IEPE interface is supplied, and the transmission distance is larger than or equal to 100km.

Three-axis monolithic microelectromechanical system (MEMS) accelerometers and methods for fabricating integrated capacitive and piezo accelerometers are provided. In an embodiment, a three-axis MEMS accelerometer includes a first sensing structure for sensing acceleration in a first direction. Further, the three-axis MEMS accelerometer includes a second sensing structure for sensing acceleration in a second direction perpendicular to the first direction. Also, the three-axis MEMS accelerometer includes a third sensing structure for sensing acceleration in a third direction perpendicular to the first direction and perpendicular to the second direction. At least one sensing structure is a capacitive structure and at least one sensing structure is a piezo structure.

A piezoelectric device is provided with a piezoelectric element including a piezoelectric layer exhibiting a polarizability γ smaller than 1×10−9 (C / (V·m)) in the case where an electric field is applied until polarization is saturated and a circuit having a means to set a minimum value of a drive electric field to become larger than a positive coercive electric field of the above-described piezoelectric layer and a means to set a maximum value of the above-described drive electric field to become smaller than (Pm′ (maximum value of polarization)−Pr′ (quasi-remanent polarization)) / (1×10−9) and, therefore, an object is to drive the piezoelectric element in an electric field range in which maximum piezoelectric characteristics are obtained, improve the characteristics of the piezoelectric device, and enhance the reliability.

To provide an acoustic generator for which peaks and dips in frequency characteristics of sound pressure are minimized, as well as an acoustic generation device using the same. This invention is an acoustic generator, and an acoustic generation device using the same, wherein the acoustic generator has at least a diaphragm, and a plurality of piezoelectric elements which are attached to the diaphragm so as to be mutually spaced apart and which vibrate the diaphragm. The plurality of piezoelectric elements comprise at least two types of piezoelectric elements (1, 2) of different thickness. In each of two mutually intersecting directions upon the main surface of the diaphragm, piezoelectric elements (1, 2) of different thickness are disposed. Accordingly, it is possible to achieve an acoustic generator, as well as an acoustic generation device, for which peaks and dips in frequency characteristics of sound pressure are minimized.

A piezoelectric accelerometer comprising a housing with two complementary parts (2005, 2006) in which a metal mass (2002) and an abutting piezoelectric element (2003) movably mounted in place are sandwiched between two conductive contact elements (2001, 2004), wherein the metal mass (2002) is in intimate contact with the piezoelectric element (2003) and the two conductive contact elements (2001, 2004) act as the electric terminals for connecting the accelerometer to any external electronic circuit for further processing.

The invention discloses a high-impact piezoelectric accelerometer. The high-impact piezoelectric accelerometer comprises a hollow installing seat, a core is arranged in the hollow installing seat through a compressing ring in a press fit mode and is connected with a cable through a plug, one shock insulation cushion and one insulating cushion are arranged between one end of the core and the compressing ring, and another shock insulation cushion and another insulating cushion are arranged between the other end of the core and the installing seat. Because the shock insulation cushions large in damping are installed at the two ends of the core of the piezoelectric accelerometer, high-frequency large-amplitude acceleration generated by strong-impact waves on a structure can be filtered out, and transverse acceleration transmitted to an acceleration sensor can be reduced so as to achieve the purpose of reducing zero drift. Due to the adoption of a base strain isolation type structure, strain of sensitive elements can be effectively reduced; because the insulating cushions are arranged at the two ends of the core and serve as isolators, the accelerometer can be isolated from an installing face mechanically so that effective strain transmitted to the accelerometer can be reduced and the purpose of reducing zero drift can be achieved.

An acoustically driven ferromagnetic resonance (ADFMR) device includes a piezoelectric element, a pair of transducers arranged to activate the piezoelectric element to generate an acoustic wave, a magnetostrictive element arranged to receive the acoustic wave, and a readout circuit to detect one of either a change in the magnetostrictive element or a change in the acoustic wave.