Actuation stiffness calibration of space inertial sensors using a two-stage torsion pendulum

Abstract Electrostatic stiffness is a key parameter governing space inertial sensors, and its precise characterization via applied actuation voltages is critical for determining the residual acceleration of the test mass along the sensitive axis. In this paper, we investigate the dependence of this stiffness on the maximum actuation range within a dedicated model. A closed-loop calibration experiment utilizing a custom-designed two-stage torsion pendulum equipped with capacitive sensors and an AC feedback control system was performed. For electrostatic stiffness near 10 -4 N/m, measurements agree with theoretical predictions within a 1.6% deviation. The stiffness exhibits direct proportionality to both the maximum actuation force and torque. These results validate the constant stiffness model and provide guidelines for optimizing in-orbit electrostatic control parameters.