Kevin Worrall

Volume-constrained robotic missions seeking to obtain samples from beneath a planetary subsurface may wish to use a rigid drill string consisting of multiple, individual drill bit sections connected together, as opposed to a single, lengthy drill bit. To ensure that drill strings can be assembled and disassembled reliably, it is essential that a robust connection system be used. The authors propose a geometry that seeks to address the requirements of such a mating interface. The proposed solution is based on the bayonet interface, using L- and T-shaped so-called female grooves and male studs connected and disconnected together through a series of clockwise and counterclockwise rotations and single-point clamping events. This routine allows the transfer of both percussion through the drill string and torque in both directions of rotation, while permitting the accurate disconnection of individual drills bits at the required location. Sustained laboratory and field drilling operations suggest that bayonet-style connections offer a reliable solution to the problem of autonomous assembly and disassembly of drill strings in a planetary exploration setting. This paper discusses the development of such a connection system, based on the bayonet connection, which has been implemented in the overall architecture of the Ultrasonic Planetary Core Drill (UPCD). The design trade-off study, which sought to evaluate the use of the bayonet system in comparison with the more conventional screw thread interface, will be discussed, alongside experimental results from percussion transmission testing and drill string assembly testing.

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An ultrasonic auger was designed, manufactured, and tested in glass microspheres to investigate force and torque reducing effects upon application of high-powered ultrasonic vibration. It was found that whilst vibration had no effect on overhead force during rotary augering, the torque was reduced by up to 30%, depending on amplitude of vibration.

This work presents the methods used and initial findings of the control of the model for an autonomous trenchless drilling device, with bioinspired worm-like locomotion. The model is validated using Inverse Simulation. The initial control is detailed with data from the simulation and experimental device.

Failure Detection, Isolation and Recovery (FDIR) of autonomous systems working in hazardous conditions is essential. Methods of detection and recovery without intervention are required. This work describes the failure modes currently identified with an autonomous biologically inspired trenchless drilling robotic system. Inverse Simulation is used for detecting failures and is demonstrated on a simulation model of the robotic system. Results from the experiments, show that Inverse Simulation can be used to detect and identify system failures.