Open Cut » Maintenance & Equipment
Bucket fillability in open cut mining operations has a major influence on the productivity of electric rope shovels. The characteristics of bucket filling can be described in terms of the amount and distribution of material in the bucket and the ease of the digging operation. The enhanced sensing of machine and operator performance is crucial in advancing the automation of rope shovel operations and in improving safety of loading operation.
This project was undertaken to:
- Develop a prototype system capable of imaging the surface of the material in the bucket during normal machine operation; and
- Integrate the imaging system with the CRC Mining Shovel Data Acquisition and Feedback System.
To achieve the specified objectives, a prototype High Speed Radar System was developed at the University of Sydney, Australian Centre for Field Robotics, and tested on an off-line P&H 2100BLE Shovel at Bracalba Quarry. The radar system was shown to have the ability to generate digital images of the material surface in the bucket during normal shovel operation and to integrate with the CRCMining Data Acquisition and Feedback System.
The results of the field trials show high-quality bucket surface scans obtained from the radar scanner. Radar system accuracy was verified against images obtained via video system during testing demonstrating highly acceptable correlation in terms of the material distribution in the bucket.
In addition to material surface imaging and its distribution within bucket boundaries, the outcomes of the field trials also indicate that the High Speed Radar System has the ability to:
- Differentiate between individual bucket teeth;
- Perform face scanning and determine shovel distance to the face;
- Identify other objects (vehicles) within shovel vicinity.
Information acquired by the bucket imaging system, when coupled with other monitoring equipment, such as, face profiling and payload monitoring, would provide means to evaluate and improve bucket fillability, bucket payload, bucket trajectory during the digging process and, ultimately, bucket design for specific mining conditions.
The development of the high speed radar scanning mechanism faced many challenges related to the internal radar operation and scanner field performance. Those issues were addressed as follows:
- Increased scanning speed of radar scanner to perform imaging in real-time.
- The original signal processor of the AcuMine radar was modified to accommodate a scanning rate of more than 4000 samples per second from the original sampling rate of 5 samples per second.
- Vibration due to high mirror rotating speed. The rotating mirror produced a rotating moment at the mirror hub, which induced significant vibration. This problem was overcome by dynamically balancing the mirror using a stainless steel counterbalance.
- Vibration and shock loading due to operation of the machin e. The radar scanner must remain on the shovel for extended periods of time and it is subject to severe vibration and shock loading due to the nature of shovel operation. A specifically design mounting assembly was manufactured to provide shock protection functions and limit the vibrations of the scanner.
- Limited field of view due to shovel bail obstruction. For bailess buckets, the radar assembly can be attached directly to the boom of the shovel, providing a clear view of the bucket. However, the radar's field of view is limited if the shovel bucket has a bail. In this case, an extended mounting assembly was designed and manufactured to allow proper scanning range of the material in the bucket.