  Non-sensitive axis feedback control is crucial for cross-coupling noise
suppression in the application of full-maglev vertical superconducting gravity
instruments. This paper introduces the non-sensitive axis feedback control of
the test mass in a home-made full-maglev vertical superconducting
accelerometer. In the feedback system, special superconducting circuits are
designed to decouple and detect the multi-degrees-of-freedom motions of the
test mass. Then the decoupled motion signals are dealt with by the PID
controller and fed back to the side-wall coils to control the test mass. In our
test, the test mass is controlled successfully and the displacement is reduced
by about one order of magnitude in the laboratory. Accordingly, the noise level
of the vertical superconducting accelerometer in the sensitive axis is also
reduced.
