Abstract
Recently dragcup type induction generators with direct current operated as accelerometers are widely used in direct measurement of shaft angular acceleration. In these cases, it is important to obtain accurate calibration data for the actual measurement of acceleration. Many methods for calibrating an accelerometer's performance have been put forward quite well, but they are not yet sufficient.
In this paper, we studied this problem for the case when a universal joint is adopted as the driving unit of a velocity variation. The outline of the discussion about the calibrating method is as follows; (1) An angular velocity variation based on a universal joint occurs two times during one revolution of a shaft (n=2), and its angular acceleration can be calculated by αm=(cosγsin2γ)ω02 on the restricted condition (γ<10°). (2) The calibration data for twice the velocity variation can be obtained easily from the above equation, and the results hold in all cases of n=2. (3) Even if a velocity variation is not equal to n=2, the calibration data can be calculated using Eqs. (19), as the gain constant K and the rotor time constant Lγ/Rγ of the sampled machine can be decided respectively utilizing the values of the above equations when n=2.
