Method for calibration of dynamic motion sensors

#The invention relates generally to methods and systems for accurate calibration of dynamic motion sensors. A dynamic motion sensor (“motion sensor” or “sensor”) is defined as any transducer measuring time varying displacement and/or acceleration including but not limited to accelerometers, velocimeters and displacement probes.

#In one aspect, dynamic motion sensors are transducers used for measuring acceleration. Single axis or uni-axial dynamic motion sensors are generally sensitive along a single axis. For example, acceleration magnitude may be measured by means of an external instrument or measuring system sensing the electrical output of the accelerometer. The accelerometer output may be a voltage waveform proportional to the magnitude of the applied acceleration. Similarly, dynamic motion sensing devices such as velocimeters and dynamically responding displacement transducers may output a voltage waveform or generate current proportional to velocity.

#A dynamic motion sensor to be tested is referred to herein as a Sensor Under Test or “SUT” and a high accuracy reference sensor is referred to as “REF.” ISO16063-21 is an ISO standard entitled Vibration Calibration by Comparison to a Reference Transducer.

#The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which:

#FIG. 1 is an idealized front view of a prior art dynamic motion sensor calibration system;

#FIG. 2 is a front view of the exciter component of the dynamic motion sensor calibration system of the present invention;

#At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical structural elements of the invention. It also should be appreciated that figure proportions and angles are not always to scale in order to clearly portray the attributes of the present invention.

#While the present invention is described with respect to what is presently considered to be the preferred embodiments, it is understood that the invention is not limited to the disclosed embodiments. The present invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

#The invention provides a solution that can very accurately calibrate a dynamic motion sensor at low frequencies. Low frequencies are defined as 10 Hz and lower. The dynamic motion sensor under test is placed on an electrical or electromechanical exciter with the axis of sensitivity oriented parallel to the stroke axis of the shaker. One form of such an exciter is a long stroke shaker. The output signal is connected to a computer system through appropriate signal conditioning and digitized by an analog to digital converter card for digital signal analysis.