A bird’s eye view

Police helicopters fitted with a sophisticated surveillance camera system are commonly known as an ‘eye in the sky’. This term, at least outside Japan, has rarely been linked with the crane industry.

Cameras mounted on the end of crane booms are a widely used safety feature in Japan but are virtually unheard of elsewhere. Techno Fine aims to change all that by introducing its new system in the USA, where it has been demonstrated on sites in New York City and New Orleans.

Despite the rapid advance of electronics technology over the last few years, crane operations still rely on hand signals and radio communication. The crane camera system means that the load can always be in the operator’s line of sight because a real-time video image of the view down the hook line is displayed on a monitor in the cab. Safety is improved because the operator can react more quickly and accurately to emergency situations without having to interpret or wait for potentially unclear information to come from a banksman via radio or hand signals.

Japan’s high population density and constraints on space make the accurate operation of construction cranes all the more critical. The Japanese government is considering making fitment of crane camera systems mandatory, according to Namik Idil, general manager at Techno Fine USA. The government has suggested that they be fitted where cranes are working on road overpasses in cities and at elevated sections of railway because of the proximity to residential and office buildings. These ‘recommendations’ are almost always followed by contractors and have the force of law, Idil says. They are actually an edict to contractors, saying that it is better if they use the system. No action will be taken if a contractor chooses not to, but if another contractor uses the system and completes the job more quickly and with less property damage, then those who have fitted the system will be first in line for future contracts, it is suggested.

Most of the 1,600 crane camera systems in use in Japan are mounted on crawler cranes, and all were supplied by just two manufacturers, Fuji and Ikegami, according to Idil. Now Techno Fine has entered the market and already has orders for 200 systems which are to replace existing units, he says.

The Techno Fine system can be mounted on almost any type of crane, it is claimed. Camera angle, focus and zoom (up to 10x) can all be adjusted by the operator in the cab using remote control to give a better view. A stepping motor gives up to 15m of movement along the x–y axis.

Many advantages are claimed for the new digital system over the old designs. Weight is significant because it can be enough to change the crane’s load chart – the camera housing alone, of the hydraulically operated Fuji system, comes in at 200kg. An early version of the Ikegami system (of which about 20 units were installed) weighs about 60kg. Ikegami had a design for a lighter, 15kg, system until its developer retired from the company and formed Techno Fine, so Ikegami’s plans were shelved. Techno Fine’s housing weighs only 8kg which has significantly less impact on the chart.

Cranes act like huge aerials and attract electronic noise which adversely affects the old systems by reducing image quality and making controller commands unreliable, Techno Fine says. The earth’s magnetism, magnified by a crane’s structure, can also have similar effects. Techno Fine’s multiplex signal transmission allows data to be carried over long distances without losing image quality.

The cable connecting camera and monitor on the Fuji and Ikegami systems is specially made, difficult to handle and expensive, compared with Techno Fine’s coaxial cable, Idil claims. This standard cable is readily available and can be extended to suit longer booms using BNC connectors.

Advanced monitor design is a further feature of the new system. Conventional cathode ray tube screens use one electron gun to produce the image but Techno Fine’s flat screen design uses 16 and the enclosure can be a panel shape rather than a box. The incoming analogue signal is converted to a digital one and then fed to each of the guns to produce a high resolution full colour image which, unlike LCD screens for example, provides an undistorted view from any angle.

A flexible neck on the camera housing keeps it vertical at all times, whatever the boom angle and an auto-brake mechanism locks the housing when the power is switched off to prevent wind damage. This mechanism also stabilises the housing against the wind and engine vibration. The camera is housed in a stainless steel drum and can be used in all weathers. It operates from a 24V DC supply.

Installation time for the complete system is claimed to be less than two hours and can be done on site.

At $19,000, the camera system is an additional cost, but the benefits make it well worth considering.

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