Investigation on actuation to sensing crosstalk in the space inertial sensors

Abstract Inertial sensor (IS) is one of the most critical units in space-based gravitational wave detection projects. Any actuation to sensing crosstalk in the IS might lead to operational anomalies in sensing electronics, thereby affecting the closed loop control of the test mass. The theoretical model for the crosstalk has been analyzed and verified. A secondary-tuning method is proposed to suppress the actuation to sensing crosstalk. Considering the influence of the circuit’s stray capacitance which acts as the equivalent primary resonance tuning capacitance, experimental results indicate that the secondary-tuning method could attenuate the crosstalk factor by 5, compared to the traditional primary-tuning method. The actuation to sensing crosstalk is reduced, and then the measurement accuracy of the displacement sensor is relatively improved. Based on the theoretical crosstalk model, the criteria for selecting the basis function waveform of the feedback voltage are provided. When the basis function of the feedback voltage is selected to be a 150 V sinusoidal signal, the primary-tuning method requires a frequency of less than 337 Hz, while the secondary-tuning method allows for a frequency of less than 528 Hz according to the experimental results. The requirement for the feedback voltage frequency in the secondary-tuning method has been relaxed nearly by a factor of 1.5, which allows for large frequency intervals and could suppress the coupling between the actuator’s degrees of freedom.