THE MEAN-PROJECTION METHOD FOR THE TRANSVERSE CALIBRATION OF ACCELEROMETERS - I - THEORY

The cross-axis or transverse sensitivity of accelerometers is a common concern in vibration measurements. The mean-projection method is aime d at calibrating the accelerometer with shakers that are commonly avai lable in laboratories. Its principle is presented here with an analysi s of the sources for errors; another paper will be devoted to the expe rimental aspects and results. The basic feature of the method consists in shaking the accelerometer along one direction and averaging the me asurements taken at different angles when the accelerometer pivots aro und the main axis of the shaker; this yields its sensitivity along tha t direction. Ideally, three such series of measurements should suffice . Applying this method with a wide frequency-band excitation reveals s everal complications: the motion of the shaker has a rotation componen t, its translation has generally an elliptic polarisation, the motion is slightly sensitive to the position of the equipment which permits t he revolution of the accelerometer for a series of measurements. It is possible to correct for the effect of these complications by means of a fourth series of measurements in which the accelerometer is placed in the opposite direction, compared to one of the three initial series .