The electric null of the position sensor of a drag-free satellite is expected to change its location with respect to the geometrical center of the sensor due to aging. This offset creates an increasing nonlinearity in the sensor's response, causing distortion of the output signal. A technique has been developed to identify the amount of null offset from samples of the output signal only when the disturbances on the satellite are relatively constant. A linearized least squares fit is used. Difficulties are caused by parameter equivalence of first order and data noise near the center; however, accurate estimation can be obtained for large null offset.

Marcelo Crespo da Silva

Papers

Attitude-translation coupling in drag-free satellites