Welcome to the second Automating your World column, a series of advice articles by Position Partners' technical experts. In this series of articles, we look at the various aspects of machine control solutions.

One of the questions I am asked most often is: “How does the 3D system know how much to cut?”

Many prospective 3D grade control buyers quickly grasp the concept that a GNSS (Global Navigation Satellite System) receiver mounted on the blade of a motor grader can give you the position of the cutting edge of the blade in real time.

However, how the computer in the cab knows where grade is and how it gets that information deserves an explanation.

Before we proceed, though, let’s review what the 3D grade control system actually does.

In short, an on-board computer in the cab has a digital copy of the site plans stored in its memory and a GNSS receiver combined with various on-board sensors tell the computer the position of the cutting edge of the blade.

The computer then makes a determination of how far the cutting edge is from grade and sends a signal to the hydraulics to drive the blade to grade. This comparison is done several times per second, creating a real-time 3D grade control system.

When we use a 3D grade control system we are essentially bypassing the traditional process of grade staking.
Instead of giving site plans to the surveyor, who uses these to set stakes and then having the machine operator visually read those stakes, we are now putting the site plans on a screen directly in front of the machine operator.

In order for the system to have useful information to work with, the site plans have to be prepared in a format that the on-machine computer can understand.

A site model, or DTM (Digital Terrain Model) needs to be created – either from paper plans or from the engineer’s CAD (Computer Aided Design) file.

When starting with 2D printed plans (Fig 1), information on the paper will have to be manually transferred to a computer in an office environment.

 

 

Co-ordinates, along with templates and alignments must then be turned into digitised linework (Fig 2). There are a number of software packages on the market that can do this, so check with your machine control system sales representative for what he recommends.

Once in the office computer, this linework can be further transformed into a DTM (Digital Terrain Model) through a process often referred to as “tinning”. TIN stands for Triangular Irregular Network and is the description of a mathematical method of creating surfaces from a set of point

 

Lines are drawn between three close points to create a surface between them. This process is then repeated using adjacent points until the whole site has been turned into a 3D surface, comprised in turn of tiny, triangular surfaces (Fig 3).
On some projects the engineer can make a CAD file of the site available. If this can be obtained, a DTM can sometimes be generated more easily.

However, it is important to remember that the engineer’s CAD file shouldn’t go directly in the machine; rather it needs to be “stripped down” to only the relevant grade information.

Manufacturers of 3D grade control solutions often use proprietary formats (types of DTMs) in their on-machine computers.
This is because DTMs created for purposes other than grade control often are large and difficult to use in a real-time application.

So, in order for the system to run well, the on-machine computer will often require a specific format and one that differs from those of other manufacturers.

This is normally not an issue, as most manufacturers supply conversion software with their 3D grade control system, which will convert an industry-standard DTM to the specific format required in their on-machine computer.

Additionally, these software packages also contain a data model viewer that is very helpful in controlling the quality of the data you put into your 3D system.

A viewer allows you to look at the completed model from all angles, spin it around and zoom in and out. If there is an error in the data, it is usually easy to spot as it will show up as a “wild” grade break.

While a machine operator can learn the basics of a 3D grade control system in about a day, learning how to prepare the data models can take a bit longer.

If you are doing it in-house, you’d want to give the task to someone with CAD experience. The trick in learning how to make a good data model is knowing which pieces of information the machine wants.

When considering the purchase of a 3D system, be sure to ask your supplier about the data preparation. Your supplier should be able to give you a good understanding of the data flow as it relates to that particular system and let you know which options are available for training on how to prepare the data models.

They should also tell you if the conversion software comes with the system or if it has to be purchased separately.

The data is a very important part of your 3D grade control system. It need not be difficult, but it helps to be educated about the process so you can better implement the technology in your company.

Grade well, grade quickly.

A new series of high-quality, affordable machine control sensors – the LS-B100 series – was recently announced by Topcon Positioning Systems (TPS).

 

The LS-B100 series, including the LS-B100, LS-B110 and LS-B110W (wireless), offers a modern new design and increased functionality.

Replacing the LS-B2 and B4 models, the new series provides the tightest accuracy and largest working range of machine control receivers in the market today, according to Neil Other, Topcon Positioning Systems Australia and New Zealand sales manager.

“The LS-B100 series is ideal for dozers, box blades, excavators and backhoes,” he said.

"Its unique features, such as on-grade matching and wireless capability, offer unmatched performance on any job site."

Features of the LS-B100 family include:

• Large working range
• Most accurate receiving resolution
• Wireless display capability
• On-grade matching function
• Plumb indication
• CAN compatible
• Four selectable dead bands
• Universal pole clamp.

The units use rechargeable or alkaline batteries.

The first LPS-900 3D local positioning machine control system is providing millimetre-accurate machine control for a Cat 12G grader engaged in small-scale paving applications around Brisbane.

The LPS-900 combines a robotic total station with precision machine control to provide what is said to be the world’s most advanced, high-accuracy local positioning 3D control system.

Topcon’s LPS-900 system features its X-TRAC® tracking technology and integrated radio communication for higher-speed operation under all conditions.

It is designed for users requiring millimetre-accurate final trim capability in applications where the multi-machine capabilities of Topcon’s Millimetre GPS™ are not required, or in built-up or heavily treed areas where satellite availability may be an issue.

It also offers a simple, cost-effective transfer path to GPS-based 3D machine control, including Millimetre GPS.
In addition, it can also be used as a survey total station.

On the LPS-900’s first Australian application, the 12G grader, owned by Universal Civil Contracting, has been achieving accuracies to within 5 mm on a small commercial development in North Lakes, to the north of Brisbane, according to operator Grant Thiele.

As of late March, Thiele had been using the LPS-900 system on the project for about two months, from final trim of the earthworks, to putting down the basecourses prior to asphalting.

“We’re easily getting to within 5 mm accuracies with this system; it works really well, and is much easier for putting the gravels in,” he said.

“It’s particularly critical to get that sort of accuracy for the top-course before you put the asphalt on; when you’re putting on 35 mm of asphalt, you don’t want to put any more down than you have to.

“We went for the LPS-900 system rather than standard GPS-based machine control because we really needed the accuracy here. We found it much easier with the Topcon LPS System because it got to within the mill we wanted, while the GPS only got you between 20 and 10 mm,” said Thiele.

Topcon’s mmGPS system would also have met or exceeded the high-accuracy spec, but given the relatively small job size, Universal Civil opted for the added engineering versatility of the LPS system.

“It takes me about 30 minutes to set it up each morning, or about half that if there’s someone here to help me – and after that, it’s right for the day,” he said.

Although this was his first application with machine control, Thiele said he had no trouble picking up the system.

“I’m finding it very good, much easier on me. It means I’ve got more hands to work the other levers.

“This Topcon system is perfect for this application; it’s easy to operate and gives us the precision accuracy we need,” he said.

Welcome to the first Automating your World column, a series of advice articles by Position Partners' technical experts. In this series of articles, we will be exploring the various aspects of machine control solutions – from a simple stick-on laser receiver on a backhoe to full blown 3D machine control systems using satellite positioning technology to automatically control motor graders, dozers, excavators, pavers and profilers.

 

Sometimes referred to as grade control systems, machine control systems are now an everyday sight on construction sites around the world. If you do not already use such systems, chances are that you soon will.

Just a few years ago, contractors bought machine control systems to get a ‘leg up’ on their competition. The increase in productivity achieved with these systems allowed them to greatly reduce their bids and still maintain a healthy profit.

The ability to maintain tight tolerances lead to great material savings, thus reducing the cost of earthmoving operations and adding to the contractor’s bottom line.

Today, however, this technology is quickly becoming standard and contractors are realising that they need to implement this technology simply to stay competitive. Bidding a job now without factoring in the productivity gains from machine control is becoming increasingly difficult.

Everyone working in the construction industry nowadays has at least heard about machine control and hardly a month goes by without a magazine having a special feature article detailing the use of these systems on some high-profile project.

What is not always clear, however, is what differentiates the various types of systems. Exactly how do they work? How does the site plans get into the machine? Which system is most suitable for a special application? How can I get started with this technology and how should it be maintained?

In these columns, we will examine these questions and try to provide you an answer that is simple and easy to understand.

We hope this information will serve to educate the reader and assist those who are contemplating investing in machine control in making an informed decision.

For those who are already using this technology, we will explore ways to maximise the utilisation and productivity of existing systems. We plan to look at some unique machines and specialty applications as well.

While machine control systems have been around for a long time, they were previously limited to grading in a plane or following a physical reference such as a stringline or curb and gutter.

Today, the biggest excitement in the industry comes from the use of 3D machine control systems.

These systems are capable of grading complex surfaces such as super-elevated curves without the use of any pegs or stringlines. This 3D technology was introduced commercially less than 10 years ago, but it has already become a necessity on large earthmoving projects.

Head contractors and project managers are increasingly specifying that subcontractors use this technology as well. That the requirement to use machine control is trickling down to the subcontractor is no surprise.

The project owner wants to ensure that the job stays on schedule and that all work is done to specification. For this to happen, every stage in the construction process must stay on schedule, rework must be kept to a minimum and change orders must be executed ‘yesterday’.

Machine control systems can assist with all of the above and help keep cost down as well.

While the project owner gets his road built well, on time and to specification, other parties in the construction process also benefits from this technology.

Reducing rework (which often comes out of the contractor’s own pocket) is in itself a great thing, but this technology also helps the contactor to better utilise his fleet.

Reducing the number of passes to get to grade reduces both fuel and labour cost and reduces the wear on the machine. Increasing the productivity of each machine allows the contractors to use fewer machines on the job and keeping the grade as close to tolerance as possible generates great material savings.

The machine operator in turn also benefits by having a system that makes it easy for him to maintain grade, regardless of the conditions. Automated machine control manages the blade elevation for the operators and also gives steering indication.

This lets the operator focus on managing the material instead of the blade elevation, leading to less operator fatigue.

Lately, another issue has helped accelerate the implementation of machine control: The construction industry skill-shortage (something which even the current industry downturn is likely to only affect in the short term).

As most of you are painfully aware of; a whole generation of master operators have either retired or are close to retirement and it has been difficult both to recruit and retain new machine operators.

Contractors world-wide have discovered that implementing machine control on their sites not only lets their good operators do more, it also allows fine grading to be done with lesser-skilled operators.

With an automated machine, the time it takes for an operator to become proficient is greatly reduced — and a shorter learning curve means less training cost.

Interestingly, Australia and New Zealand have been pioneers in developing machine control solutions.

In fact, all the major manufacturers of these systems have research and development operations right here in Australasia.

The mining industry here has helped develop much of the underlying technology and the systems we use in construction today have a lot of things in common with the ones used in the mining sector. No doubt, our region will continue to play a very important role in the field of construction automation for a long time to come.

We hope you will enjoy this column and that you will find it helpful in making decisions about construction automation. Next time we will take a closer look at the inner workings of a 3D machine control system.

Grade well, grade quickly.