Smart surveying

25 April 2008

Hilti's PR25 rotating laser features a water, dust and heat protection system alongside an inbuilt “

Hilti's PR25 rotating laser features a water, dust and heat protection system alongside an inbuilt “shock” warning device.

Arguably the most “basic” surveying tools available to contractors are optical, or laser levels. Common features found whatever the manufacturer, include ease-of-use, quick set-up and one-touch self-levelling; the user roughly levels the instrument using a three-screw levelling head and centres a bull's eye bubble. After the bubble is manually centred, an automatic compensator takes over, levels the line of sight, and keeps it level while measurements are being taken.

Pentax's new four model PLP-600 range of lasers – PLP-601R, PLP-602R, PLP-601 and PLP-602, for example, are automatically self levelling within a +/- 10% range and Pentax's compensator system ensures this is achieved quickly and accurately.

Aimed at the general construction market, the PLP-600 range is based on Pentax's PLP-50 and PLP-5H ranges. The PLP-601R and PLP-602R are supplied with rechargable battery packs and chargers.

The PLP-601R and PLP-601 provide 254 mm accuracy within a 200 m working range, while the PLP-602R and PLP-602 have an accuracy of 305 mm over a 120 m range. Other features include, IPX6 Water Protection (strong-jet hose proof), and a sturdy design. All models are also supplied complete with the LS-6 Receiver and LA-6 Bracket. Manual mode enables basic slope measurements to be made, while the auto beam shuts off if it is knocked out of alignment to prevent measurement errors.

Elsewhere, Topcon has extended its RT-5S series lasers with the addition of the RT-5SW long-range laser. It is designed primarily for controlling earthmoving equipment on large-scale construction projects.

As with previous models in the RT-5S series, the new laser has a five arc second accuracy, which equates to less than 2,5 mm per 100 m.

It is also equipped with a SmartLine automatic guide alignment and automatic grade matching features, which makes setting up faster and more accurate. A remote control function means the laser can be operated from distances of up to 350 m.

Trimble has also launched two new lasers, the LL4400 laser level and the HV401 horizontal vertical laser.

The LL400 is a fully automatic, one button self-levelling laser level for concrete and site preparation applications. It can withstand a 1 m drop onto concrete, and a variety of power sources are available. It can be customised to meet specific application needs with either the Spectra Precision Laser HR550 or CR600 Receiver.

The HR550 Receiver can be used either as a handheld or rod-mounted unit and is “especially suitable for basic elevation control applications”, according to the company. Featuring a durable, lightweight composite housing the HR550 uses easy-to-read LCD and LED displays. The CR600 Receiver is ideal for longer range levelling and basic machine control applications.

Rotating lasers

The HV401 features a one-button self-levelling operation, and a long-range remote control. Like the LL400 it can with stand a 1 m drop on to concrete and is IP66 dust and waterproof. Power comes via either batteries or direct power to reduce downtime.

It also features a bright beam, and a range of rotation speed and scanning functions for superior visibility.

According to a Trimble spokesman, the HV401 was developed specifically to operate in both horizontal and vertical modes in a wide variety of interior and general contractor applications. Interior applications include drop ceilings, sloped ceilings, layout of interior walls and framing, and interior fittings and fixtures.

Exterior applications include cut and fill measurements, layout of excavation lines, positioning of concrete forms and pinning footers, lay out of control lines, elevation control and slopes on grade.

Like the HV401, Hilti's PR25 is a rotating laser that allows a single operator to perform levelling and alignment accurately, quickly and easily. Its auto alignment and surveillance feature allow operators to work efficiently on-site, while its water, dust and heat protection system (-20 to +50°C) means it works “whatever the site conditions”, said a company spokesman. An inbuilt “shock” warning device alerts the operator if the device has been touched or moved.

Total stations

If the laser and laser level are arguably the most simple tool at the disposal of surveyors then perhaps one of the most advanced is the total station. It incorporates an electronic or digital theodolite, an electronic distance measuring (EDM) device and a microprocessor in the same unit. (A theodolite measures horizontal and vertical angles, horizontal distances, and determines elevations.)

Therefore total stations can measure horizontal and vertical angles as well as slope distances from a single set-up. From this data they can calculate horizontal and vertical distances, elevations and coordinates, and display the results on a small screen. This data can be stored on board and downloaded later, once the operator has returned to the office for example, or to a data logger in the field.

Topcon's GPT-7000i digital imaging total station features its new Digital Imaging Measurement (DIM) technology. Rather than seeing the target object through a lens the operator can view a real-time image on the on-board computer's display.

The image can be used to guide field data collection, and then saved for use at a later date. Topcon's new PI 3000 companion software enables continued analysis and measurement of the target image with a desktop computer. Combining images with a position-linked high-resolution digital camera can extend functionality.

The 7000 Series Windows-based computers feature a touch screen display and a user-friendly graphical interface. A dual-optical, pulse laser design provides focused beam accuracy on long distance measurements – up to 250 m reflectorless, and 3 km with a prism. Other features include a compact flash card slot that can be used for additional memory or a Bluetooth card for wireless communications.

Also new is Trimble's The SPS700 robotic construction total station, which incorporates new robotic technology for increased speed and longer battery life. It features direct reflex (DR) reflectorless distance measuring for one-person operation, without a prism to measure inaccessible points and minimise manpower.

According to the company the benefits of the system include construction layout specific application programs that perform all jobsite layout and measurement tasks, its ease-of-use system means a short learning curve, while data storage and built-in checks help eliminate mistakes.

Many total stations, such as Leica's SmartStation, for example, now include GPS receivers as standard.

“With SmartStation you don't need to worry about control points, traverses and resections. Just set up wherever it's convenient, touch the GPS key and let the SmartAntenna do the rest,” said Norbert Johler, Leica's marketing and communication manager.

“RTK (Real Time Kinematics) determines the position to centimetre accuracy within a few seconds at ranges up to 50 km from a reference station. With SmartStation you're ready to go in the shortest possible time; fix the position with GPS and then survey with the total station,” added Mr Johler.

All surveying and GPS operations can be controlled via a keyboard, with data stored on the same CompactFlash card. All measurement, status and other information are displayed on the screen. The SmartStation's plug-in battery also powers the GPS SmartAntenna and RTK communication device. Everything is integrated into one compact unit so there is no need for cables, external battery, or data logger.

SmartStation's modular design also means that once it is positioned the operator can take off the SmartAntenna, put it on a pole, and use it with the RX1210 controller and GTX1230 sensor as a fully-fledged RTK rover.

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