Machine Control: It's More than Just Lasers

Laser beams and sonic beams are being placed on more and more equipment leading to increased accuracy, improved productivity and cost saving

Article December 28, 2000
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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.

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