Open Cut » Overburden Removal
This report describes the CSIRO Dragline Swing Assist (DSA) technology and the performance of the proof-of-concept system installed on the BE1350 dragline at Boundary Hill. DSA is a radical new technology for dragline operation and can be seen as an addition to any other dragline technology (eg. Parallel rigging, or Universal dig & dump). The productivity trial provided the first extended test of its operation. Results indicate that the technology is reliable and that for some, but not all, digging situations can exceed the average operator performance.
The trial was conducted over 2 weeks in November 2002 and over 3,000 computer controlled cycles were performed. The number of cycles achieved was unfortunately well short of the targetted 10,000 and this does raise issues about the statistical significance of the results. The shortfall had many causes, all beyond the control of the research team, and included unprecedented levels of downtime, extremely difficult spoiling, and operational constraints.
The production trial has clearly demonstrated that it is possible for a computer to emulate all of the essential operator skills: disengaging from the bank, dumping and bucket recovery. The most significant points from the trial are that:
- The system is able to match or exceed operator performance in some, but not all, cycles.
- Return time was significantly better than swing time.
- Subjectively the system has a skill level equivalent to an operator with 6 months training. Particular skills such as bucket disengage, dumping and recovery are performed consistently well.
- The system is highly reliable, there were no hardware or software failures over the duration of the trial.
- The system's operator interface is intuitive and was readily accepted by the operators
At this stage of development the computer's skills are not perfect, but based on experience gained during the trial they can be improved with further research. Some of the performance difference is that, unlike a skilled operator, the computer control system cannot skim the bucket close to the spoil pile since terrain information is not available to it. The best path for the bucket to travel is a function not just of machine limits, but also of the terrain and the particular dig and dump point. At all times during the trial, for machine safety, we chose conservative bucket paths to avoid bucket/spoil collisions. The resultant overhoisting imposes a clear time penalty on the DSA system.
The report concludes with a recommendation outlining next steps in the enhancement of this technology.