On the other hand laser vibrometer systems detect relative displacements as opposed to the absolute measures of accelerometers. Ngl portable vibrometer and grinding wheels balancer. Evaluation of a miniature accelerometer with a laser. Measuring mechanical vibrations using an arduino as a slave i. Ngl vibrometer and grinding wheels balancer portable vibrometer and grinding wheels balancer with 4,3 graphic display. Accelerometer accelerometer is used for measure the acceleration of the vibrating body.
Two stores of particular concern are the the mk84 and the gbu10 bombs when these munitions are attached to the wing with a. Optical fiber based multipoint laser vibrometer enabling. D single shaker laser vibrometer and accelerometers e diffuse acoustic. This manual is written for operators of process monitoringcontrol systems using vibrometers accelerometers for vibration measurement. Air force is interested in performing a ground vibration test or gvt on f16 wing stores. Some of the advantages of a piezoelectric accelerometer are. It is well known to all researchers who have experience in vibration measurements that values of acceleration amplitude can be very low at low frequencies and that a limitation to the use of accelerometer can be due to the threshold parameter of. In the next setup, the boundary conditions of the plate are changed.
Pdf comparative study between laser vibrometer and. Micro electro mechanical systems accelerometer that. Accelerometers should weigh significantly less than the structure you are monitoring. Shaker table with mounting fixtures and accelerometers the mounting system is shown schematically in fig. Comparison between accelerometer and laser vibrometer to measure traffic excited vibrations on bridges.
Pdf the use of accelerometer based measurement techniques for evaluating bridge forced vibrations or to perform bridge modal analysis is. The laser vibrometer that oki developed was able to measure vibrations of 80khz, the maximum frequency possible with the test equipment available in the laboratory. Laser doppler vibrometer type 8329 quality control laser doppler vibrometer type 8335 uses noncontact measurement of vibration velocity. The model we have used is mounted on a breakout board from sparkfun and use the adxl335 3axis accelerometer from analog devices 1. In order to have both sensors in the same point, it is necessary to locate the laser vibrometer with an angle of 30 with respect to the radial direction of the bearing. A comparative study between laser vibrometer and accelerometers for the detection of mechanical faults in a motor has been reported in 117.
A new, high sensitivity laser vibrometer sciencedirect. In some application, we need to vibrate a machine or structure to find its resonance characteristics. A screenshot of the video from the camera is shown in fig. Measuring mechanical vibrations using an arduino as a. Accelerometer is an instrument to measure the acceleration of a vibrating body. In addition, all respective analysis calculations are located in appendix b, and all references can be found in section 7. Attachment 9, data acquisition system installation and test. Citeseerx document details isaac councill, lee giles, pradeep teregowda. An accelerometer placed at any one point on the geared motor will measure a complex vibration waveform as shown in the time drawing on the left side. Test facility and method a bearing test rig, shown in figure 1, was employed in this experimental study. This information is useful for model development and stability. Accelerometer and vibrometer signals were recorded.
The laser beam from the ldv is directed at the surface of interest, and the vibration amplitude and frequency are extracted from the doppler shift of the reflected laser beam frequency due to the motion of the surface. Mar 25, 2002 the use of accelerometer based measurement techniques for evaluating bridge forced vibrations or to perform bridge modal analysis is well established. This paper presents a comparative study between accelerometer and laser vibrometer measurements aimed at quality measurements carried out on composite material shaft and beam. The monnit wireless vibration meter sensor uses an accelerometer to measure vibration speed and frequency and report on 3 axes. Polytec laser vibrometer and piezo accelerometer instrument description vibration damping and isolation are very important fields of study of the dynamic behaviour of a structure. Laser doppler vibrometer measurement head and chain. Automated modal testing using a fullfield vibrometer. Meggitt sensing systems designs and manufactures complete condition monitoring and vibration monitoring and measurement solutions. The lower deck of the bridge and the measurement point. Doppler vibrometer and the measurement results of actual vibrations generated in a. The accelerometer detector of the vm63a can be used without an attachment or with two kinds attachments s and l, to fit the respective measurement.
View and download castle ga2002 operating manual online. A set of no defective and defective motors were analyzed by means of the acceleration signal provided by the accelerometer, and the displacement and velocity. Gs can be replaced with metric ms2 or imperial units ins2. Using laser doppler vibrometer and accelerometer techniques by joseph dupuis may 2003 chair. Align laser vibrometer with actuator accelerometer pair 3. Figure 2a is the spectral waveform and 2b is the time waveform. Vibrometer, seismometer, accelerometer, shaker table. The polytec pdv100 portable digital laser vibrometer provides a noncontact vibration measurement of a structure and is very suitable to measure the. Mechanical and aerospace engineering ground vibration testing is the process of determining a structures dynamic response to a force input. Ono sokki has been providing various kinds of vibration related products to meet versatile requirements beginning with accelerometers which are trigger for detecting vibration, impulse force hammer used for natural frequency measurement, laser doppler vibrometer for highsensitivity vibration measurement and analyzers for the obtained vibration data etc. Piezoelectric accelerometer type ca 201 description the ca 201 accelerometer is equipped with a symmetrical shear mode polycrystalline measuring element, which has internal case insulation. In fact, the excitation signal and the vibration sensor output signal were connected to two of the input channels of the 16channel digitizer in the hp mainframe.
Analyze accelerometer output and compare with vibrometer data to. These converters are used with the piezoelectric pressure transducers and accelerometers. An accelerometer is a device that senses the different types of accelerations or vibrations. It describes the installation and general use of these systems. Comparative study between laser vibrometer and accelerometer. Manufacturing metrology team polytec laser vibrometer and. Accelerometer calibration system 4 channels accelerometer voltage inphase photodetector quadrature photodetector velocity reference laser interferometer. Vibrometer is designed with low natural frequency and accelerometer with high natural frequency. The vibrometer mounting hardware includes a positioning goniometer to allow for alignment of the position of the laser at multiple, repeatable, and unique.
Principles of seismic transducers vibration measuring devices such as vibrometers and accelerometers are called seismic transducers that employ a springmass system to measure motion. Comparison between accelerometer and laser vibrometer to. Ca 4 ce 4 transducer head ce 4 attached electronic conditioner. The ce4 is designed and built for longterm use in extreme environments characterised by high temperatures andor hazardous areas potentially explosive atmospheres. It is large in size because of its relative motion of the seismic mass must be of the same arrangement of the magnitude as that of the vibration to be measured. Apr 05, 2014 accelerometer is an instrument to measure the acceleration of a vibrating body. Accelerometer applications, types and working principle. For prediction measurements especially on antifriction bearings the accelerometer output in gs is used to determine the bearing health.
Fine structures of the detected cardiac traces are identified with their meanings assigned and corroborated using accelerometer and. A comparative study of misalignment detection using a. The accelerometer and vibrometer were connected with external usb sound card maudio fast track ultra. The voltage output of an accelerometer can be measured as gs 0 to peak or gs peak to peak. The maximum output for an iepe accelerometer is typically 48 volts.
Acceleration is the change in velocity caused by movements of a body. Pdf comparison between accelerometer and laser vibrometer. Important parameters relating to vibration pickups vibrometers are described below. Piezoelectric accelerometers and vibration preamplifiers, theory. So vibrometer is known as low frequency transducer and accelerometer as high frequency transducer. Improvements in accelerometer calibration using fringecounting. Laser doppler vibrometers provide a noncontacting, broadband alternative to accelerometers, but large dis placements and rigid body motion can contaminate. Spectrum analysis enables us to untangle this complex waveform and make a. An accelerometer is a device that measures the vibration, or acceleration of motion.
Vibrometers accelerometers for vibration measurement. Vibrations have been measured simultaneously by a typical accelerometer for civil structures and by a laser vibrometer equipped with a fringe counter board in terms of velocity and displacements. The behavior of seismic transducers can be analyzed using the results of an sdof system subjected to the base excitation discussed in the earlier classes. The output of an ldv is generally a continuous analog voltage that is directly proportional to the target velocity component along the direction. The accelerometer measures as the name hints the acceleration that it being is subjected to. Ground vibration testing of airplane pylonstore dynamics. In contrast, the mems accelerometer has a natural vibration that changes depending on its weight, and it has dif. Comparison between accelerometer and laser vibrometer to measure traf.
Mechanical fault detection of electric motors by laser. A typical vibrometer currently in use utilizes a mems micro electro mechanical systems accelerometer that detects acceleration from a change in capacitance between the movable and. The outcome is that the accelerometer mounted on top of the armature detects a different acceleration than what is measured by the laser vibrometer next to it. Vibrometer controller iq demodulator computer daq acceleration velocity. The reason for using mems sensorbased accelerometers is that they can sense the vibrations even on a microscale and can also provide the value on a microscale. The most frequent accelerometer used in aerospace is microelectromechanicalsensorsthe mems technology based. Thought out the calculation, the peak shock acceleration value of accelerometer is 5 ms 2 and the peak shock acceleration value of laser doppler vibrometer is 500 ms 2. If the instrument is designed to record the measured quantity, then the suffix meter is to be replaced by graph 10. Jul 15, 2020 this accelerometer can create a 3d vector of acceleration in the form of orthogonal components.
The mac values between the same modes from measurement and simulation are displayed in fig. The influence of different vibration exciter systems on high. The experiments have been carried for different number of layers and fiber orientation of composite material beam. Pcevdr 10ica is a singleaxis accelerometer or vibration meter with. A concise conclusion of each analysis section of the three transducers can be found in section 5. Noncontact cardiac activity monitoring using pulsed laser. The vibrometer mounting hardware includes a positioning goniometer to allow for alignment of the position of the laser at multiple, repeatable, and. Aug 01, 2006 in every measurement, both the accelerometer and the vibrometer signals were acquired simultaneously. Vibration is a dynamic phenomenon observed as a toandfro motion about. It is based on a aluminum cube with through holes for direct mounting of qflex type servo accelerometers or different adapters for inline mounting of accelerometers, flat mirrors. Nachiketa tiwari,department of mechanical engineering,iit kanpur. Accelerometer, laser vibrometer, and stereophotogrammetry measurement systems all have advantages and drawbacks, so each must be implemented where they will be most effectively employed, many times in conjunction with another technique.
A laser doppler vibrometer ldv is a scientific instrument that is used to make noncontact vibration measurements of a surface. Vibrometer, seismometer, accelerometer, shaker table youtube. Setup an actuator with an accelerometer attached to actuating tip 2. Comparison of image based, laser, and accelerometer measurements. Input 20 m peaktopeak signal into actuator at specified frequency 4. This is the summation of all the vibration present at that location. Spectrum analysis enables us to untangle this complex waveform and make a representation. Piezoelectric accelerometers ca xxx ce xxx macacee this document contains important information about products that are intended for use in ex potentially explosive atmospheres. Signals monitored by both sensor types were recorded by pc software audacity 1.
Ce4 piezoelectric accelerometer vibrometer by meggitt. Comparison of image based, laser, and accelerometer. The vibrometer is mounted directly above the accelerometer on a suspended mount on an isolation platform. The plate is fixed from two sides using two needles, and excited by the shaker at the same time.
A piezoelectric accelerometer has two types which are high impedance. Castle ga2002 operating manual pdf download manualslib. The modal analysis from the conventional accelerometer test was restricted to the first two modes, at 592 hz and 933 hz. The piezoelectric accelerometers are used at the industrial level. Such a contacttype vibrometer is attached to the measurement target either permanently with screws or detachably with magnets. It can be seen in the spectral waveform, the laser vibrometer detects only pure 10khz vibration, and the time waveform also shows a noisefree.
Ca xxx or ce xxx range of piezoelectric accelerometers. Our comprehensive, highquality range of transducers, sensors, cabling, electronics, software and associated hardware gives you total solutions for monitoring and protecting your critical machines and processes. Evaluation of a miniature accelerometer with a laser doppler vibrometer to study vibrations at the neck of a violin in realistic playing scenarios matthias fl uckiger. The ce4 piezoelectric accelerometer is a highquality, highreliability vibration sensor with a ceramic piezoelectric sensing element and attached electronics that provides a current output. Aug 01, 1990 the 50 db upper velocity limit of the vibrometer is determined by the bandwidth of the input bandpass filters at op and 2c. The transducer is designed for heavyduty industrial monitoring and measurement of vibration. The solution for this is to remove the motion of the vehicle by attaching accelerometers to the transmit apertures and subtracting the lineofsight accelerometer measurements from the laser vibrometer measurements. A vibrometer or a seismometer is a device to measure the. Improvements in accelerometer calibration using fringe. The noise floor of the camera for this nine second measurement is 40 nanometers, while the laser vibrometer has a noise floor of 0. Fundamentals of vibration measurement and analysis explained. Pdf comparison between accelerometer and laser vibrometer to.
An accelerometer absorbs the vibrations created by the body and uses it to know the orientation of the body. As vibration isolation and reduction techniques have become an integral part of machine design, the need for accurate measurement and analysis of mechanical vibration has grown. Two stores of particular concern are the the mk84 and the gbu10 bombs when these munitions are attached to the wing with a pylon integrated. Exelon corporation nuclear dryer vibration instrumentation. A 2 mw hene laser was used, producing an incident intensity target beam of 1 mw. Operation manual vibration meter vibrometer baltech vp. Accelerometers with integral electronics have a maximum output voltage determined by the circuit design and the input voltage. Primary calibration of accelerometers using laser interferometry. Resulting conclusions were drawn indicating how these techniques aid in understanding the pyroshock phenomenon. It consists of a 3phase electrical induction motor to provide a prime power source and a dc generator to apply load to the. Correlation between three facial vibration measurement.
Use this type when you need to determine the type of vibration, such as lateral, transverse, or rotational. Collect vibrometer data and accelerometer data for 20 seconds 5. Evaluation of a miniature accelerometer with a laser doppler. Piezoelectric accelerometer ce 311 accessories cg 310 connector gsi 122 gsi galvanic separation unit jb 105 jb 116 junction box k 209 k 2 transmission cable mechanical drawing marking marking minimum bending radius. If the instrument is designed to record the measured quantity, then the suffix. The use of accelerometer based measurement techniques for evaluating bridge forced vibrations or to perform bridge modal analysis is well established. Accelerometers are by far the most traditional and widelyused sensors employed in modal testing. Nov 19, 2010 motion of the laser vibrometer head cannot be distinguished from the motion of the target.
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