Satellite guided plant, claimed to be on the verge of revolutionising time consuming muckshifting and tunnel driving operations, was revealed for the first time at last weeks Bauma plant show.
Machine guidance systems, which enable site plant to be guided by computer, promise massive productivity improvements and significantly reduced project duration.
Ami Bergstrom, electronics engineer with US satellite guidance company Trimble Navigation claims that ' opencast mines using the system have seen a 30% improvement in productivity and increased operator satisfaction.' Trimble Navigation has teamed up with US plant giant Caterpillar to launch their jointly developed Computer Aided Earth moving System.
The guidance systems, which allow plant operators to watch a real time display on a cab mounted screen of excavation work achieved, are characterised by a continuous two way flow of information between an on board computer and the engineer's office.
The information flow is generated in the engineer's office where an initial computer file is created containing 3D survey information of the existing site. A computer aided design file of the required earthworks is then overlaid onto the survey file and transmitted by radio signal to the onboard computer.
The operator now has a simple display showing the existing earthworks profile overlaid by the finished shape. This gives a quick indication of the work to be done.
Continuous global positioning systems (GPS) or total station signals allow the on board computer to plot exact plant movements on screen.
This onboard computer records and transmits terrain details to the site office computer five times every second. This office computer, which is able to monitor several machines at the same time, combines all the details and produces a single up to the second model of the site. This is then transmitted back to the machine.
The plant operator can watch a multicoloured site plan where each colour signifies the work done on a particular piece of ground. For example, the colours might represent the number of passes of a compactor across an area of highway sub base material. If the required number of passes across that area is shown as red then the redder the display the closer it is to the optimum number.
The updated terrain model can also be fed into planning software so allowing the engineers to create new plans for the following day or week. Exhibitors claimed that this more accurate information allowed the operator to work more efficiently and removed the need for time consuming surveys.
Is this the first step towards operator free plant? Possibly; but not for some time yet.
Mark Nichols, general manager of mining and construction for Trimble Navigation, explains that we are at the first phase in the technology path towards autonomous machines. He says the next phase would see 'operator assistance technology' with guidance computers controlling the machine instruments in the same way as laser systems can today.
The difference is that these new systems can work in 3D whereas todays laser systems are one dimensional.
Operator free machines are used today in the US and Japan for handling hazardous waste. But these are closed environments where site safety is easy to manage. Nichols stresses that 'it will be a long time before we see fully autonomous machines on the building site because we need to be able to guarantee site safety.'