Like the human eye, coastal surveillance tools are limited in their range by the curve of the horizon – without help, no one can see over the curve of the sea.

An academic at ADFA in Canberra is developing mini-helicopters to overcome this dilemma and other surveillance problems.

Lecturer from ADFA’s school of aerospace, civil and mechanical engineering, Matt Garratt, tinkers with his 1.5 m helicopter which sits neatly on his desk. The 7.5 kg uninhabited aerial vehicle (UAV) is a scaled-down prototype of a 100 kg helicopter platform which could be flown from coastal surveillance vessels used by the Australian Customs Service and the Royal Australian Navy.

The prototype has already demonstrated the preliminary generation of systems which would allow a UAV to maintain a stable position tethered above a ship which is being tossed about in high seas, and to land and launch from a heaving deck automatically.

When these aids to staying in position and landing safely have been fine-tuned, the full-size helicopter should be able to maintain position at more than 1,000 m above the ship.

An autonomously operating helicopter must be able to measure a vast range of variables, particularly for landing and during changes in the ship’s position. Its primary instruments, most of which have been built from scratch at ADFA, include gyroscopes, a differential global positioning system, magnetometers and accelerometers, which measure the motion of the helicopter. It also carries a front-mounted camera which can be used to determine distance from the deck and relative ship motion in the horizontal plane.

Once in production, the current sensor and control systems on the helicopter could be kept to a total weight of several hundred grams. This makes completely autonomous surveillance drones weighing as little as 1 kg a realistic prospect in the near future.

Garratt, a former Navy engineer, says that later untethered generations of the autonomous mini-helicopter could be used for short-range surveillance – to reconnoitre a bay which is concealed from the ship by a headland or to fly past or hover at a window in a terrorist situation or siege.

Another potential spin-off from this research may be the capacity to increase the safe range of operations for manned helicopters at sea. There is a high risk of accidents for manned flights and training for both aircrew and maintenance personnel is expensive and time-consuming. A highly automated platform requires minimum operator training and poses no risk to aircrew. Crew would only be required to launch and recover the proposed system, which could potentially be operated for days at a time.

Garratt’s work could also assist the pilot of a conventional helicopter operating in adverse weather conditions. About half of the launch and recovery problems of helicopters at sea are related to excess pilot workload rather than limitations of the aircraft. As weather conditions deteriorate, ship motions become harder for the pilot to monitor and sometimes the pilot is no longer able to respond quickly enough to keep the helicopter in a safe flight path in relation to the ship’s flight deck.

Automatic control systems can be designed with much faster response times than humans and could potentially take over some of the workload of controlling the helicopter close to the deck. Implementation of a partial authority flight control augmentation (PAFCA) system could enable the range of helicopter operations to be expanded in those areas where pilot workload is limiting. A PACFA system would also reduce pilot fatigue and help to reduce accidents.

Garratt is the lead investigator for a 2004 Australian Research Council linkage grant with an industry partner Avesta. They hope to use the research to open up new roles for the RMAX (100 kg) helicopter UAV, which Avesta markets in Australia and New Zealand. The RMAX is employed in various roles worldwide including crop-dusting, aerial photography and exploration.

Garratt is also funded by the Defence Science and Technology Organisation to investigate new computer-assisted flight controls for aiding pilots in full-size helicopters operating from ships. He will be working with Dr Himanshu Pota from ADFA’s school of information technology and electrical engineering on the ARC linkage project.