An extra dimension
Article written by Bernhard Marx at Moba.
Although 2D technology offers several advantages for efficient road construction, a new range of 3 D systems will help even the most complex construction plans to be undertaken in record time – while ensuring optimal quality.
For projects as diverse as building highways in Germany or racetracks in India, 3D-controlled machines are being used more and more frequently in today’s roadbuilding industry. For earthwork in particular, not only can time, money and material be saved, but personnel can also be reduced with the use of 3D- supported levelling systems. However, there are limits to what 3D technology can do. In other words, 2D machine control still offers some clear advantages over 3D systems, such as in asphalt construction, for example.
As an experienced system specialist in mobile automation, Moba Mobile Automation AG offers the full spectrum of 2D and 3D control systems for machines involved in road construction from excavators to dozers, pavers, and rollers. Moba’s reliable control systems, tried and tested in application, give both building contractor and vehicle operator a clear advantage: with a higher work speed and simultaneous enhancement of precision and performance, they can improve the efficiency of machine use and successfully complete projects faster. At the same time, the use of these technologies makes work easier for the vehicle operator. The machine works more precisely, the work process is continuously checked and errors are prevented.
3D control for graders
With Moba 3D, the company offers a levelling system that is optimally suited to the 3D processing of construction sites for application in graders as well as dozers.
If Moba 3D is used when creating a foundation, the layers van be represented exactly in 3D. A very exact plane can be created with the use of 3D-controlled machines, so that almost no corrections are needed for later asphalt work.
Depending in the project and phase of the project, there is a choice between Mona 3D GS, equipped with a GNSS receiver, and Moba 3D TS, which works with a tacheometer. The satellite-controlled Moba 3D GS model lends itself well to levelling substrate. Using a satellite, the system is able to permanently determine the position of the machine.
The GNSS antenna is compatible with other GNSS reference stations.
Surveying with guide wires at the construction site becomes unnecessary, saving building contractors time and money and reducing the number of personnel required.
When creating planes, 3D control in association with a tacheometer is highly advantageous. In particular, the benefits of GOS is that no additional surveying stations need to be assembled, while tacheometers are optimally suited for fine levelling, as highly exact elevation accuracy can be achieved.
Even when there is no satellite reception, for example in tunnels, alleys or between tall buildings, precise work with tacheometers is still possible. But when conditions are good, a working range of up to 200 metres can be obtained. The main advantage of working with tacheometers is that levelling is carried out in an extremely precise manner, with an accuracy of ±5mm.
Moba 3D for exact planarity
With Moba 3D, even the most difficult construction plans can be implemented quickly and efficiently. The terrain type can be captured three-dimensionally early on in the surveying stage so that the data can be used as a foundation. The project data is transmitted via USB interface to the construction machine and depicted on the display.
All project data, such as cut and fill values as well as 3D project models, are displayed for the driver on the 10.2in touchscreen. Information can be easily read in all situations on the clear function displays. The clear presentation on the panel and easy menu navigation facilitates training and system handling. The touchscreen panel is protected against vibration, dust, dampness, heat and cold.
During work on the project, the 1.6GHz controller records the incoming actual values of the longitudinal slope and cross-slope sensor as well as the rotation compensator. These are adjusted with the target design and compensated for accordingly on the blade.
Both Moba 3D GS and Moba 3D TS with the GS-506 hydraulic control which precisely maintains the blade height and slope. If a machine is already equipped with the Moba GS-506 2D system, a problem-free upgrade of the 2D system to Moba 3D is possible due to the modular building block structure of the systems.
If a large amount of earth has to be moved, such as when building a large street in hilly terrain, the use of an excavator is advisable. So even in the excavation control sector, Moba has the right system for 3D project processing: the Vision 3D.
Optimal asphalt construction
Whenever the advantages of 3D technology for levelling substrate and planes are needed, the use of Moba Big Sonic-Ski in asphalt construction lends itself perfectly to the application. If the foundation is created exactly in 3D, the remaining uneven areas can be evened out easily with the Big Sonic-Ski’s ultrasound measurement system.
GPS systems are not suitable for superstructures, because their elevation accuracy is not sufficient. But even when compared with 3D systems that work with tacheaometers, the Big Sonic-Ski, which works with ultrasonic sensors, has clear advantages: while additional personnel may be required to install and operate tacheometers for the use of three-dimensional technologies, this is unnecessary with the Big Sonic-Ski.
When tacheometers are used for asphalting, they have to be constantly adjusted so that the paver does not move outside the signal range. If, for example, a distance of six metres – which the paver would cover in one minute – is anticipated, the tacheometer would have to be repositioned after 15 minutes to fulfil quality requirements.
In Comparison, handling the Big Sonic-Ski is much easier, as it works without requiring additional personnel or external reference stations. Check measurements can be made by on-site personnel. An additional advantage is that, even in terms of consistent layer thickness and planarity, the Big Sonic-Ski achieves results that are noticeably more exact than those of 3D systems.
The Big Sonic-Ski consists of three ultrasonic sensors for contact-free height scanning; artificial references are not needed. This means an area of 13 metres can be scanned. Every second, each sensor performs five different ultrasonic measurements 11 times. From all these measurements, a mean value is calculated and a virtual reference level is derived – this is how uneven reference levels are detected and balanced out.
With fivefold scanning, the Sonic-Ski works much more precisely than a simple ultrasonic sensor and achieves 1mm accuracy during ground sensing. Flexible sensor positioning improves the manoeuvrability of the paver so that even curvy routes can be processed.
Certifiably greater evenness is achieved through the use of the Big Sonic-Ski. Its simple assembly and system construction facilitates use. When combined with the Moba-matic operation unit, this offers the user diverse adjustment possibilities, but with just four buttons remains very easy to use.
The final compaction of the material plays a decisive role in achieving optimal results in road construction. Easy to initialise and operate, Moba’s Material Compaction Assistant (MCA) is the right systems for optimal material compaction. The MCA allows the roller operator to keep track of compaction on the entire route of the project by monitoring the overruns.
The system therefore assists the operator by constantly detecting the current position of the roller via GNSS signal. The antenna receives both GPS and GLONASS signals. Using this position determination, the number of overruns during the entire project are recorded, and target and actual overruns are adjusted. This means the operator always knows which areas have already been sufficiently compacted and where overruns are still necessary. Vehicle stops are also saved with more exact position information. With the help of this data, the operator is able to restart work exactly where he/she left off. Optionally, the MCA can also display the temperature of the material.
A flexible combination
The factor that makes all Moba systems stand out is the modular building block system. It allows all components to be flexibly combined and subsequent expansions to be implemented easily due to open system structure. If the machine requirements should change, the Moba systems can be adjusted problem-free.
One final big advantage is that all electronic components are protected against damage from heat, cold, dampness dust and vibration by a special potting compound and are therefore optimally suited for use in construction sites. iVT
Bernhard Marx is product manager for levelling systems and compaction at Moba, where he has worked for six years, after more than a decade working for Leica and Bomag