Precise in situ characterization of the mechanical properties of lunar regolith is critical for future lunar base construction and resource exploitation. However, existing detection methods predominantly rely on indirect inversion from rover wheel-soil interactions, which exhibit limitations in accuracy, real-time capability, and detection depth. Furthermore, specialized automated equipment capable of adapting to the complex lunar surface environment remains lacking. To address these challenges, this study presents the design and development of a novel autonomous in situ penetration-shear apparatus. The device automatically executes penetration and shear operations while recording real-time data, with a maximum penetration force of 25 N, shear torque of 2.5 N·m, penetration depth of 300 mm, and rotation angle of 360°. Given the maximum normal load constraint of 16 N imposed by the lunar rover platform, 24 probe configurations—varying in conicity, projected area, and vane number—were systematically evaluated using lunar soil simulants with three particle size distributions and two density levels. Multi-objective optimization was conducted to maximize detection efficiency, specifically penetration depth and shear torque, subject to a lightweight payload constraint (16 N). The multi-objective optimization reveals a fundamental trade-off: smaller conicity angles and projected areas favor deeper penetration, while larger projected areas enhance shear torque response. Under the 16 N constraint, the Pareto analysis identifies that a combination of moderate projected area, small conicity, and fewer vanes achieves the most balanced performance across all soil conditions. Results further demonstrate that increasing particle size and density substantially suppress both penetration capability and shear torque response, with compaction being the dominant factor limiting probe advancement under constrained normal loading. Results indicate that the optimal probe configuration comprises a 15° conicity, 324 mm2 projected area, and two vanes, achieving an average penetration depth of 51.61 mm and average shear torque of 0.06 N·m across all test conditions. This study validates a complete automated system for characterizing lunar soil mechanical properties and provides an efficient, reliable hardware solution for future unmanned lunar exploration missions through optimized probe design. These findings establish a solid technical foundation for deep, high-precision in situ investigation of lunar soil structure and mechanical parameters, with significant implications for lunar base site selection and In Situ Resource Utilization (ISRU).
Liu et al. (Thu,) studied this question.