Abstract
The dual-reciprocating drill (DRD) is a low-mass alternative to traditional drilling techniques biologically inspired by the wood wasp ovipositor, which is used to drill into wood in order to lay its eggs. The DRD reciprocates two halves lined with backwards-facing teeth, enabling it to generate traction forces that reduce the required overhead penetration force. While previous research has focused on experimental testing of the drill’s operational and design parameters, numerical simulation techniques are being developed to allow the rapid testing of multiple designs, complementing and informing experimental testing campaigns. The latest DRD design iteration integrated a novel internal actuation mechanism and demonstrated the benefits of adding controlled lateral movements. This paper presents an exploration of how bit morphology affects drilling performance and a preliminary study of discrete element method (DEM) simulations for modelling DRD interactions in regolith. These have shown how regolith grain size and microscopic behaviour significantly affects the performance of different drill designs, and demonstrated how customisable drills can exploit the properties of various substrates. Two system prototypes are also being developed for the DRD’s third generation, each utilising novel actuation and sampling mechanisms. A final drill design will then be deployed from a planetary rover and perform the first DRD drilling and sampling operation.
Highlights
Drilling systems often play a critical role in planetary exploration missions
While rotary drills are commonly used in terrestrial applications, large masses are needed to provide the overhead force (OHF) necessary to push the drill into the substrate
This study examined the forces experienced by the Dual-Reciprocating Drill (DRD), which provided further insight into the relationship between penetration, traction and lateral forces as discussed in Section 1.1.2 [20]
Summary
Drilling systems often play a critical role in planetary exploration missions. By accessing the subsurface of extraterrestrial bodies, they are able to make in-situ measurements, confirm observations made by remote sensing instruments, search for biomarkers indicating the signs of life and the presence of water-ice, acquire samples to be taken back to Earth, and more. While rotary drills are commonly used in terrestrial applications, large masses are needed to provide the overhead force (OHF) necessary to push the drill into the substrate. This makes them unsuitable for planetary exploration, given the stringent mass constraints imposed upon a mission and low gravity on other bodies such as the. Complex systems, they have been used on several missions, including ExoMars [3] and Curiosity [4]. Another percussive technique is the mole, which is Biomimetics 2020, 5, 38; doi:10.3390/biomimetics5030038 www.mdpi.com/journal/biomimetics
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