Inchworm Drilling System for Planetary Subsurface Exploration

The physical properties, sequence structure, and heat flow of planetary regolith are important information to enhance the scientific understanding of lunar evolution and the origin of life, as well as for future planetary activities and resource utilization. An inchworm drilling system for planetary subsurface exploration missions is proposed in this article. The inchworm drilling system consists of an inchworm drill and a chip removal device, and this article provides a detailed description of the system design. Reasonable drilling parameters in the regular drilling condition are recommended based on drilling load analysis, and a manipulation strategy is given for troubleshooting in the faulty drilling condition. Robotic drilling experiments were carried out on a lunar regolith simulant, and the drilling depth of the inchworm drill reached 850 mm in 106 min. In addition, parameter identification tests of the simulant mechanical parameters were carried out during drilling, and the shear strength parameters of the simulant cohesion and internal friction angle at five locations along the depth direction were measured. The experimental results show that the proposed inchworm drilling system can well achieve the mission target of drilling and exploration and is a feasible choice for future planetary exploration missions.