Open Cut » Overburden Removal
The Caterpillar Semi-Autonomous Tractor System (SATS) enables autonomous bulk push mining operations for overburden removal. It can execute various bulk-movement methods including Push-To-Edge, Tip-Head, and Pivot-Push. The SATS system in its current commercial form autonomously and progressively completes bulk-production bulldozing through the use of missions created by an operator at a remote workstation. These missions act as "packages" of work for the bulldozer to complete, with one operator able to oversee multiple bulldozers, each executing their own missions.
This project has extended SATS through the introduction of the SATS Tactical Automated Mission Planner (STAMP). Specifically, the project has investigated the benefits of autonomously generating missions for a team of SATS-enabled bulldozers engaged in pivot-push mining. The mission creation process takes into consideration the shape of the work block being pushed and employs optimisation methods and models to determine the most efficient push plans for the bulldozer team.
STAMP takes on the responsibility of planning and organizing the work for each bulldozer, providing the operator with missions for approval. The operator can oversee multiple machines at once. STAMP's mission plans conform with the pit design and adhere to operating constraints such as maintaining even tip-head progression, maintaining a specified push grade, and ensuring acceptable inter-slot height variations between adjacent slots. To keep the bulldozers in continuous operation, STAMP also plans to prevent situations where two bulldozers finish their missions simultaneously and continually adjusts the mission sequence as the push progresses, adapting to any actual work variations, similar to how a turn-by-turn car navigation system operates.
The project conducted two trials which are fully described in the report:
- Compare SATS with manned operation and found that they had similar productivity levels (measured by LCMs moved to prime per unit of time), with SATS having a slight advantage;
- SATS operators were provided with missions generated by STAMP and given the option to accept or reject them.
The work is significant because it demonstrates the potential for substantial operational improvements in bulldozer mining through the use of automation technologies and in particular the benefit of providing satisficing decision support to operators in planning missions.