Wyniki 1-1 spośród 1 dla zapytania: authorDesc:"Łukasz KĘDZIERSKI"

High speed imaging method for rotational speed calibration DOI:10.15199/48.2019.05.43

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Rotational speed calibration poses a general problem to users working with motors as there is no direct measurement standard (in a sense of a true embodiment of the unit [1]) one can rely upon like in the case of weight, length, time and so many other measurements. In such a case an indirect standard is needed. It is natural to use time as a measurement standard for rotational speed sensor calibration as the SI unit for rotational speed is radian per second [2]. However, it is common to use revolution per minute (rpm) as the unit for rotational speed (the calibration method proposed in this paper uses rpm as the preferred unit). It is an industry standard to use strobe light for the purpose of calibrating the sensors measuring rotational speed. This method is based upon the fact that when periodically moving object (such as a rotating shaft of the motor) is illuminated by a strobe light of frequency equal to the frequency of the object rotation, then the object appears to be stationary [3]. If the frequency of the strobe light can be accurately measured then the speed of rotation can be calibrated with the equal accuracy. The strobe light method suffers from two major drawbacks though. First is the aliasing - object appears to be stationary at a given frequency but it will look exactly the same when the frequency of the strobe light is doubled, tripled and so on. Second drawback is the accuracy of stroboscopes - even the top quality products when operating in rpm mode will introduce an inaccuracy of 0.02% ±1 rpm when measuring speeds above 1000 rpm [4]. High speed imaging method proposed in this paper doesn’t suffer from the aliasing and is more accurate thanks to the very precise internal clock. Test stand The test stand consists of VFD (Variable Frequency Drive) controlled asynchronous electric motor driving a shaft through a gearbox. The shaft of which the speed is measured can rotate within 500÷12000 rpm ran[...]

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