The heart of solving the longwall automation challenge is knowing the three dimensional position and orientation of a longwall shearer. Steering the shearer, horizon control and face alignment are all linked to knowing where the shearer is in space, as is chock advance.

 

Even today, with several discrete pieces of longwall equipment already highly automated, string-lines are fly-cuts regularly used to straighten coal faces and overcome gateroad 'creepage', resulting in a loss of production. Also, existing horizon control methods alone do not provide the required level of performance for full automation.

 

A technology originally developed for use in highwall mining has now been adapted for trial in a longwall mine. The CSIRO's Mining and Exploration division in Brisbane, with Australian Coal Association Research Program (ACARP) project funding, is about to begin trials of a military grade inertial navigation system (INS) attached to a shearer.

 

The system autonomously logs the three-dimensional position and orientation of the shearer over many shear cycles. CSIRO researchers believe that this will provide an accurate three dimensional description of the path of the shearer throughout each shear cycle and a build model of the coal seam as it is extracted.

 

Project leader David Reid, who played a major role in the development of the HORTA highwall mining system, said in a highwall situation the inertial system achieved good results underground over distances of up to 500m, where GPS will not work.

 

"We are getting accuracies of 100mm cross-track error," Reid said. "When we realised this technology could be transferred underground we patented the application of INS to longwall guidance.

 

"This project will demonstrate that inertial navigation can be applied to these problems by accurately recording the three dimensional path and orientation of the shearer and thereby generating the signals needed to control the chock advance system. Furthermore, the inertial navigation system can provide accurate information about the three dimensional profile of the coal seam. This information can be combined with existing shearer sensor information to achieve greatly improved horizon control.

 

"We will demonstrate that we have the information to be able to control the chocks. There is no reason why each shear and each chock advance can't be initiated and controlled so that face alignment is maintained."

 

The project, which kicked off in February this year, was awarded $214,000 in ACARP funding in last year's round. The CSIRO is contributing a further $170,000 to the project, as well as the substantial experience gained in the highwall research.

 

Work to date has focused on the mounting of the experimental equipment on the shearer and providing a communications channel off the shearer for the inertial navigation unit (INU). This channel will be a point to point link between the INU and the gate-end PLC via radio modem.

 

A Long-Airdox shearer has been fitted with the INU and should be operational at the South Bulga colliery in New South Wales by mid-August. Reid said South Bulga was identified as an ideal site for the project because it had good communications infrastructure and because the mine has long been committed to the concept of longwall automation.