Bias reduction in force rebalanced accelerometers

摘要

A system is provided for the continuous reduction, in real time, of bias in a force rebalanced accelerometers having a proof mass coupled to an accelerometer housing by a flexure suspension. The system comprises a closed loop, force rebalance servo that provides control voltage to the proof mass to null an electrical pickoff signal that indicates the motion of the proof mass with respect to the accelerometer housing, wherein a time varying disturbance signal is injected into the force rebalance servo that results in the generation of a time varying voltage in the output of the force rebalance servo that corresponds to a magnitude of the net positive spring of the combined flexure suspension and electrostatic springs acting on the proofmass. The system also comprises a negative electrostatic spring servo that applies a negative electrostatic spring DC voltage to each of a pair of negative electrostatic forcer electrodes.

主权项

1. A system for reducing bias in an accelerometer having a proofmass coupled to an accelerometer housing by a flexure suspension and a pair of negative electrostatic forcer electrodes spaced apart from the proofmass on opposing sides, the system comprising:
a force rebalance servo that provides a control voltage to the proofmass in response to an electrical pickoff signal, the electrical pickoff signal indicating motion of the proofmass relative to the accelerometer housing, wherein a predetermined time varying disturbance signal is injected into the force rebalance servo that results in the generation of a time varying voltage in the control voltage, the time varying voltage corresponding to a magnitude of a net positive spring force of the combined flexure suspension and electrostatic spring associated with bias voltages acting on the proofmass as the proofmass moves in response to the time varying voltage in the control voltage; and a negative electrostatic spring servo that applies a negative electrostatic spring DC voltage to the pair of negative electrostatic forcer electrodes to cancel the net positive spring force of the combined flexure suspension and electrostatic spring associated with bias voltages acting on the proofmass in response to the nulling of the time varying voltage from the control voltage.