Concept and Approach
Leveraging existing mature trenchless excavation and environment mapping technology and introducing technical approaches and innovations inspired by robotic space technology, we envision BADGER as an underground robotic system that autonomously navigates in the subsurface by pulverizing, removing and pushing through the subsurface soil while at the same time using advanced sensing modalities, perception techniques and cognition to localise itself, map and understand the working environment and make decisions on how to better pursue its goals.
The robotic system will enable the tunnelling of small-bore networks, support and stabilization of high curvature bores, the automatic detection and annotation of utilities and buried objects as well as the mapping and visualization of the 3D underground space. At all times, BADGER will allow for complete monitoring and control of the underground operations by human workers and supports them with critical information about the process.
The robotic concept is depicted in the Figure below and comprises two main physical subsystems. The first is the underground robot that autonomously tunnels, navigates and executes tasks in the subsurface space. The second is the control console located on the surface, operated by a human. The control console will communicate with the underground robot either through umbilical (wired) connection or wirelessly using repeaters installed along the tunnel.
Schematic presenting the underground robot concept. (a) The robotic system comprises robot modules and joint modules. Joints are 3-DOF: 1 prismatic that extends along the joint axis, 2 rotational (pitch, yaw). (b) Lateral view.
Subsystem 1 physical components
Drilling head: The drilling mechanism will be based on a combination of both rotary and impact drilling technologies , which will ensure maximum efficiency and compact design. The rotary technology will be based on existing trenchless technology of partner TT into which, a novel (developed during the project) ultrasonic drill-tool will be integrated to foster pulverization of the rock. Drill heads will be modular allowing replacement depending on the application and the type of the soil.
Propulsion mechanism: Novel biomimetic propulsion will be developed that is equipped with clamping mechanisms and generates peristaltic crawling motion among the modules resulting in a net forwards (or backwards) displacement of the robot center of mass (CM).
Steering mechanism: The underground robot shall be able to steer during drilling at a desired direction (pitch, yaw angles) by means of a novel mechatronic steering mechanism that employs actuated joints to direct the drill head at pitch, yaw angles and z direction. The steering mechanism design shall target maximization of robot manoeuvrability, i.e. maximization of the curvature of the curved path the robot can describe.
Transportation of cuttings mechanism: The cuttings pushed back by the bore-head will be moved to the surface by means of a pump. The pump will be a commercially available one.
Tunnel wall support: BADGER aims to have a follower robot equipped with a printer head and a cylindrical manipulator, tasked to 3D print the walls of the bore with additive material (resin or other) and construct pipe wall support.
On-board Ground Penetrating Radar (GPR): The robot chassis will be equipped with novel GPR technology to act as active exteroceptive sensor and sense the surrounding environment. The technology will be developed during the project. The robotic chassis will be quipped also with IMU and other sensors for facilitating localisation.
All physical components of subsystem 1 will be integrated into a flexible, modular, multi-segment robot design that can articulate its segments during the drilling process to fit the curved bore.
The overall robot design is a chain-type structure, biologically inspired by an inchworm. It can be classified as heterogeneous and modular, because it consists of three fundamentally different modules: drive modules, joint modules and tool modules. Drive modules integrate the propulsion and steering mechanism, are responsible for the propulsion and they carry motion-controlled mechanisms. The drive modules are equipped with two connecting interfaces for connecting the joint modules at opposite ends. The joint modules are equipped with active joints to generate relative motion between two modules. The tool module integrates the bore-head component. The bore-head will be interchangeable depending the application. Both drive and tool modules carry power units, powerful embedded processing units, communication units and a set of embedded heterogeneous sensors such as ground penetrating radar antenna arrays, electronic navigation sensors and laser sensors that generate data for robot perception, localization and mapping. These sensors are interchangeable and their selection depends on the specific application for which BADGER is deployed.
Subsystem 2 physical components
Control station hosts the central computer that runs the supervision, planning and monitoring software. This includes the digital representation of the detected objects and utilities, a wireless communication unit and the user-interface through which the user is able to monitor the process evolution, visualize the data perceived and transmitted by the robot, and if needed tele-operate the underground robot. The control station also hosts the data management system that stores, processes and shares all the data generated by the BADGER system and the data retrieved by the BADGER remote data server and are related to legacy digital maps and utility maps.
Surface radar: A commercially available surface radar (a rover or a rollator) will be employed to facilitate the initial subsurface mapping process, either in an automatic way or manually.