Research on Calibration Technology for Lunar Soil Mechanical Parameter Measurement Module

In lunar in-situ exploration missions, the resin potting used in mechanical modules to withstand high-impact penetration environments induces nonlinear sensor responses, compromising the accuracy of acceleration signal measurements. To address this issue, this paper proposes a ‘co-planar excitation’ dynamic calibration method based on velocity parameters. The calibrated module and a standard accelerometer are symmetrically mounted on the movable platform of a shock amplifier. When the excitation pulse width exceeds 0.5 ms, both devices experience identical acceleration and velocity, constituting co-planar excitation. Based on the principle of velocity invariance, the sensitivity of the calibrated module is determined via least squares fitting. Subsequently, a dynamic correction model is established using the Subspace Identification-State Space Method（SI -SSM）. Without relying on the mechanical parameters of the potting material, this model adaptively captures the nonlinear characteristics of the sensor response through discrete state equations, thereby correcting the acceleration output. The expanded uncertainty of the corrected measurements from the mechanical module is 4.16%, meeting the technical requirements for lunar in-situ exploration.