Machine Control: It's More than Just Lasers

Dec. 28, 2000
Machines and their owners continue to benefit from the use of developing technology. For example, hydraulics and electronics have improved the versatility of excavators and skid-steers, and lasers and sonic controls have increased the precision of graders, excavators, pavers and other equipment. This translates into improved productivity.

Increased productivity and profitability are just two areas that make the use of laser and sonic-controlled machinery appealing to contractors.

Machines and their owners continue to benefit from the use of developing technology. For example, hydraulics and electronics have improved the versatility of excavators and skid-steers, and lasers and sonic controls have increased the precision of graders, excavators, pavers and other equipment. This translates into improved productivity.

Increased productivity and profitability are just two areas that make the use of laser and sonic-controlled machinery appealing to contractors. Brian Juroff, marketing manager, Topcon Laser Systems Inc., Pleasanton, Calif., explains, "Everything about a contractor's job is getting tighter. There's more competition. Cost of material is higher, cost of labor is higher, cost of machines is higher and bids are becoming tighter and tighter. The inspection process and the tolerances that the contractor must work toward are much tighter. All these things affect the profitability of the contractor.

"The most expensive portion of the contractor's job is his equipment. He's got millions of dollars worth of iron sitting on the job site. If you can show him a system that is going to increase productivity on a piece of machinery from anywhere from 25% to 100%, depending on the machine and the operator, that is something the contractor is going to look at."

Mark Forrest, product manager, Spectra-Physics, Dayton, Ohio, adds, "Contractors are looking to increase the productivity of their machines. With our products installed on their machines we can increase the productivity by up to 50% in some applications. The operator can work on his own without stopping and waiting for grade checkers. It also gives him increased accuracy as well."

Rusty Schaefer, marketing manager, industrial wheel and skid steers, Case Corp., Racine, Wis., agrees, "Laser guidance eliminates the need for an extra person in the trench checking the depth and grade, and that in turn reduces costs and increases productivity."

"It is part of the trend toward quality. It allows contractors to build better roads and bridges because of the laser's exactness," states Chuck Schaidle, technical manager, corporate mining group, Caterpillar, Inc., Peoria, Ill.

Kevin Maehling, director of products for Ramsey, Minneapolis, Minn., a manufacturer of paver controls, says that controls help improve performance. "They make the control of the paving machine much simpler. With better control the crew can lay a better mat in less time. The paver will perform more consistently and there will not be as much opportunity for human error."

Operator shortage

Another area driving the increased use of laser control machinery is a shortage of experienced operators. "The availibility of skilled operators is decreasing," says Forrest.

Motor grader operators, for instance, are highly skilled in the use of their machines. But a shortage of skilled operators is forcing contractors to look at alternatives. "There's lots of interest in laser controls because contractors are looking for alternatives, because good motor graders are hard to find," states John Marshall, sales development manager, Champion, Goderich, Ontario.

"In a climate where we constantly hear from contractors that skilled operators are hard to find, laser guidance systems can be a real plus. They can make it possible for both highly skilled and less experienced operators to easily create a level grade with a crawler dozer, or a trench graded to precise specs with a loader/backhoe or excavator," states Schaefer.

However, a contractor needs to know that lasers are not a miracle cure for operator shortages. Forrest explains, "This won't make the kid off the street a machine operator but what it will do is give an inexperienced operator the skills of a more experienced operator."

He goes on to sum up the benefits, "The big cost savings is productivity enhancement, reduced use of material, reduced labor and reduced rework and engineering costs."

Sonic control systems

When it comes to laser-guided motor graders there seems to be a bit of confusion over its use. Roads are designed with varying degrees of banks, so a road is rarely level. Roads also do not go in a straight line for great distances. They have curves and turns. Lasers do not handle curves and banks.

Topcon's Juroff explains, "A beam of light can only work in a plane. Laser- guided graders are basically working off of planes. They work either on a level surface or on a single slope, or even a dual slope depending on the laser you're working off of. So this limits the applications where [laser-guided motor graders] can be utilized."

Greg Harris, product trainer, John Deere, agrees, "Lasers can only go straight. A laser system cannot pick up the laser over a hill."

Ramsey's Maehling explains a laser configuration, "You set up a laser emitter and then have a laser receiver on the paver itself. It is used to control the elevation of the screed at a specified height. You ignore any undulations in the terrain between the emitter and the receiver."

Because of the varying elevations of the terrain covered in road work, laser-guided graders are better adapted for pad work. Maehling explains, "Laser control is used primarily on airport applications, because you can't use it on hilly terrain or on curves."

But there is a technology available to motor graders and pavers for use in road work, which is based on bouncing sound waves off of objects, such as is done with sonar. A sonic sensor device is mounted on the ends of the motor grader blade. These sensors also can be attached to a paver and used to direct paving operations.

A sound pulse is generated and a timer is started. The sound pulse will strike a reference point, like a string line or a curb. An echo is reflected, which returns to the sensor and the timer is stopped. The distance to the reference point is calculated by knowing the speed of the sound. This allows the operator to keep the blade, or screed on grade.

The only problem with sonics is that sound waves can be affected by temperature and moisture, upsetting the accuracy. However, this can be overcome by using additional sound beams, and system software to detect and compensate for changes in temperature and moisture.

Another system, which is not affected by changing elevations and the temperature, is a laser tracer device. Forrest explains Spectra-Physics' Laser Tracer, "It's a system that will follow a string line, curb gutter or previous pass. It incorporates a fan laser and a CCD camera. The CCD camera has a filter over it that is tuned to see the laser beam. When the string line breaks the laser beam, the camera shows exactly where it breaks it. Then it counts the pixel rows, like on your television screen, down to that position. We are then able to tell its position left and right as well as vertically."

He continues, "The laser tracer is mounted on the end of the grader blade in a similar position and style to the sonic tracer. The laser tracer is designed to follow the string line, giving the operator line indication."

A laser tracer device can improve accuracy. "Sound travels at different speeds in different temperatures and atmospheric conditions. Because we are using a visual type of technology here (laser tracer) we're not affected by the temperature and the wind," states Forrest.

The future

XYZ control is the future for laser- or sonic-guided machinery and this may involve the use of Global Positioning Systems (GPS). Juroff explains, "Everyone talks about GPS. What they're really looking for is three-dimensional control, XYZ control of a machine. GPS may be a portion of it and it may not be. It is not the end-all cure all. There are still questions about Z accuracy for GPS, whether it will ever be accurate enough for the type of machine control that we are talking about.

"GPS works great in mining applications and machine management. But when you are talking about controlling a motor grader that's trying to cut grade with millimeters of accuracy and they want to cut finish grade in third gear moving 20 mph, GPS accuracy isn't there yet. And it may never be there. But XYZ control is still a pie in the sky and that's what everyone is striving for."

Spectra-Physics also is pursuing XYZ control. Forrest elaborates, "The future will involve XYZ control and we started into this with a product on the agriculture side called GeoStar, which uses a combination of GPS and laser to control the equipment. With the machine they known where the elevation is on the site as well as the XY position, and they can correct the elevation of the machine by position."

Forrest discusses other plans for the future, "We are looking at real-time communication between the machine and the site office, so if plans do change, that information can be transferred out to the machine so it can automatically begin working on the new plans. The machine also will be able to give real time updates back to the office."

Maehling comments on paver controls, "They will continually move towards more automation. Controls will utilize more sophisticated technologies, yet they will be easier to use and more adaptable than their predecessors."

While new technologies are developed and explored it is a safe bet that the future of laser-controlled machinery will remain very bright. "Laser-guided machine control is just one portion of the technology base. There are other areas but for laser- and machine-control manufacturers this is the biggest growth market out there. The future is very exciting. We just hit the tip of the iceberg as far as increasing productivity and controlling machinery," says Juroff.