- If they are accessible and safe, the voids are entered by workers. Manual measurements and hand scanners are used to take surveys of the mines.
- If they are accessible, but unsafe to enter by workers, remotely operated robotic systems can be used to build up geometric maps of the voids.
- If they are inaccessible from the surface, boreholes are sunk into the workings and from them a picture of the void can be developed.
1.1. Problem Definition
1.2. Challenges of Borehole Inspection
1.2.1. Size Constraints
1.2.2. Vertical Deployment
- A system may not be able to land or navigate on the floor if it is unable to float.
- The presence of water may add significant disturbances to sensors.
1.2.4. Hazardous Obstacles
1.2.5. GPS Denied/Complex Workings
1.3. Paper Summary
2. Literature Review
2.1. Confined Inspection UAS
2.2. Actively Reconfigurable UAS
3. System Overview
- ‘Ground Station’ (GS) (Figure 4, Green) provides the input and output of data from the rest of the system to the user (‘Human Machine Interface’ (HMI)). It is physically above ground and provides power and user input to the rest of the system.
- ‘Deployment Mechanism’ (DM) (Figure 4, Red) is responsible for deploying and extracting the robot from the surface and into the void through the borehole. It consists of a dock to allow the robot to detach and reattach to it at the start and end of the mission, respectively.
- Robot (Figure 4, Blue) completes the survey. It is an autonomous inspection UAS that explores the mine workings and captures the required data product.
3.1. Deployment Mechanism
3.1.1. Protective Casing
3.1.2. Off-Board Folding
- Direct geared drive from off-board motor.
- Individual actuation for each arm.
3.1.5. Active Wall-Pressing
3.1.6. Vertical Alignment
3.2.1. Reconfigurable Compact Design
- Aplanar arms-up.
- Aplanar arms-down.
3.2.2. 3D Sensing and Mapping
3.2.3. Autonomous Flight
3.2.4. Mission Planning
4. Preliminary Confined Flight Testing
4.1. Experimental Setup
4.1.1. Confined Flight
- Test of flight controller in a confined environment.
- Test of the injection of a positions from the main on-board PC through ROS.
- Autonomous path tracking of the combined system in a confined environment.
4.1.2. Autonomous Planning
4.1.3. Autonomous Exploration and Planning Flight
4.2. Results and Discussion
4.2.1. Confined Flight
4.2.2. Autonomous Mission
4.2.3. Autonomous Exploration and Planning Flight
- The robot was able to safely follow the pre-planned path in the confined environment, Video 1 shows small disturbances as the UAS was effected by ground effect but improved tuning of the flight controller should be able to reduce that effect.
- As shown by successfully completing a safe flight, the position feedback from the VICON system was able to be injected into the flight controller through the ROS framework. Demonstrating that this works when in a region without external position feedback, the position reference will be generated from the on-board SLAM system which is still in development.
- As shown in Video 1, the robot was able to safely and autonomously track the path. Future work would be the development of the path tracking to enable smoother transmissions between way points.
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