A Flexible Upgrade

Machine grading control systems have something in common with project delivery systems
By Don Talend, Contributing Editor | October 2009 Vol. 64 No. 10
A Haydon operator views a topographical layout of the AZ job site on a GX 60 monitor while digging with a Caterpillar 330 CL.

In the spirit of construction cost control, Haydon has also incorporated GNSS grade control technology into its day to day operations over the past several years and purchased two X63 systems from Topcon Positioning Systems in 2008. The company may purchase several more X63 systems in the future as the technology becomes an even bigger part of day to day operations, according to Jeff Fields, Haydon’s GPS manager.

GNSS impacts dirtmoving
A GNSS machine control system uses a rugged antenna mounted to a shock absorbing, vibration damping pole and a receiver box mounted in a secure location on the machine. Satellites send positioning data to another antenna/receiver combination at a stationary base station. Positioning data is also sent to the machine. The stationary base and machine work together to provide real time kinetic (RTK) position information, to reveal the machine’s three dimensional location on the site. Software compares the machine’s position to the design grade at a given location. The design grade information was built from site plans.

The data files are loaded into a machine mounted control box via a USB flash drive. The control box updates positioning data and sends signals to the hydraulic valves. The blade is automatically positioned for elevation and slope. Other sensors inform the control box of certain machine conditions; for example, dozers are equipped with a slope (tilt) sensor on the blade to measure the cross slope of the cutting edge. “Indicate systems” like Topcon’s 3 D systems provide visual guidance for machine operators, who manually control the machine to cut or fill to the desired grade.

During the past several years, these systems have evolved in terms of flexibility and reliability. An alternative to a base station – that Haydon uses – is subscribing to a network that provides positioning corrections using cellular technology. Where available – such as through Branco Machinery of Gilbert, which also sold and services Haydon’s Topcon Positioning System’s GNSS equipment – this option provides flexibility. The contractor does not have to set up a separate base station on each job site.

“With a base station, you’re setting on a known point on that job. On that known point, that base station transmits to the machine or rover corrections of where it is,” said Todd Hermsen, Haydon’s Topcon sales representative. “When you move to a cellular communication with a network, the machine is actually dialing up to that network via cellular communication and receiving its corrections.”