Published in Australian Longwall Magazine

Using the automated face alignment system, developed by the ACARP (Australian Coal Association Research Program) Landmark longwall automation project, the face was straightened over three passes without operators having to run a string line.

The primary objective of the trial was to observe and document the closed-loop control of the automated face alignment system, operating under full production and closely monitored conditions.

The trials utilised all the components of the automation system – the inertial navigation unit mounted on the DBT shearer, the Landmark process controller and the Landmark-enabled Joy Mining Machinery roof support system.

The trial was witnessed and monitored by Joy and CSIRO personnel, both underground and in a monitoring room on the surface.

The horizontal path of the shearer during each shear was measured by the inertial navigation unit. From this measurement the face correction information was computed and passed to the roof support system which proportionally advanced each roof support to achieve the desired face alignment.

Prior to the first automated correction being made, the face was noticeably non-straight with a maximum deviation of about one metre.

After correction the majority of the face was effectively straight with some residual deviation in the maingate region. Information from the longwall crew indicated difficult floor conditions were encountered in the maingate region during the shift which may have restricted the armoured face conveyor push.

“We didn't get as much shearing time as we would have liked, meaning we recorded only about three corrected passes but it was enough to show that the face profile was clearly straightening, evidenced by our plots and also by direct observation underground,” CSIRO senior principal research engineer David Hainsworth said.

“To my knowledge it is the first time anywhere that continuous measurement of actual shearer position has been used as the basis of face alignment correction. All other systems currently available rely on inference of face position from measurement of cumulative shield D/A (double acting) ram motion or by direct measurement of the motion of a sample of supports using lost cord transducers.

“As we know, both methods are very unreliable.”

These initial results show automated face alignment is a reality. Next the team will introduce automatic creep control into the face alignment process. This will eliminate manual wedge cuts as well as straightening cuts leading to further productivity improvement.