A two-DOF drilling robot with a suction drill for planetary regolith exploration

Planetary exploration is critical for human beings to understand the mysteries of the universe, trace the origin and evolution of life, and promote the sustainable development of human society. This article presents a two-degree-of-freedom (two-DOF) drilling robot with a suction drill bit that may be useful for extraterrestrial drilling. The device consists of a propulsion unit and an excavation unit. The propulsion unit has a radial expansion function that can accommodate slight variations in borehole diameter and maintain the body position and orientation of the drilling robot. The excavation unit breaks up the regolith and transports the chips to the ground to make room for advancement. The cutting discharge unit transports the chips from the front end of the drill bit to the surface. This article provides the system design, performance analysis, and cutting mechanics model of the robot in detail. Among others, the cutting mechanical model was completed and validated for a tine and multi-row tines and performed well in predicting drilling loads (average error of 13.81 %). The drilling experiments were conducted mainly on the sand and lunar regolith simulant (LRS), and the robot demonstrated good performance by penetrating a depth of 520 mm in the sand within 420 s. For LRS with more complex mechanical properties, the robot reached 182 mm in 270 s, indicating that the robot can also adapt to extraterrestrial regolith drilling. With appropriate improvements in future work, this robot is considered to have possible applications in extraterrestrial exploration.