An LHD is a mid sized (up to 60 tonne) underground mining vehicle that loads, hauls and dumps (hence its name) metaliferous ore from an open stope (where there is broken rock) to a crusher or waiting truck to be transported to the surface. Since the roof of the tunnel in open stope areas is unstable, this type of operation presents a number of safety issues and provides a perfect opportunity for automation. Our aim in this project was to automate the haulage and dumping cycle for an LHD.
Our solution involved placing a number of sensors on the LHD, including high speed scanning lasers, and developing software to control the machine. Unlike competitive systems, our automation system is based upon the principals of reactive navigation and opportunistic localisation - meaning that there is no prescribed path for the vehicle to take, but rather the system continuously reacts to the environment and tunnels walls and decides how to respond. As it drives the loader builds a map of the underground structure and compares it to an abstract mine map, evaluating the information before proceeding. The advantage of this system is that it is able to tolerate errors in position and lack of traction. If the vehicle is slightly off the expected path, it can quickly regain its normal course.
- System for relative vehicle navigation United States 6694233 Issued June 3, 2002 A navigation system for navigating an autonomous vehicle along a path that is confined by walls that are within range of on-board sensors is described. The system determines the relative location and orientation of the walls with respect to the vehicle. The system controls the steering angle and the ground speed of the vehicle by employing: (a) range data to establish free space in front of vehicle; (b) active contours to generate a desired path; (c) driving hints to guide the active contours along arcs and open areas; (d) steering hints to confine the active contours to a specific domain of free space, at, for instance, intersections; and (e) a desired path to generate steering demand or velocity.