Feature 5 | UNMANNED VEHICLES
trajectory until the vehicle is positioned by Sirehna is designed to: The system demonstrator is composed
to ensure that its deck-lock engages the
•
accurately and continuously measure of an airborne unit and a shipborne
centre of the landing grid. Tracking is the position of the UAV relative to the unit, both incorporating an Inertial
accurate to 300mm, significantly better centre of the landing platform, before Measurement Unit, a GPS receiver, and
than that achieved by GPS-only systems. and after touchdown. This is achieved a realtime computer that performs data
DCNS says that SADA takes less than through real time correlation of inertial acquisition and INS/GPS correlation for
two minutes to recover a VTOL UAV and GPS measurements performed providing navigation references to the
on a moving flight deck up to sea state onboard the UAV and onboard UAV and the ship. The computation of air
5. It adds that the system is based on the vessel; and ship navigation references to obtain
open architecture principles, allowing
•
define the optimum time and position relative position, ship motion prediction
it to be readily and unobtrusively of recovery by means of a ship motion/ (using measured ship motions), approach
integrated with any VTOL UAV and any wave prediction method that exploits and decking trajectory optimisation and
suitable ship. ship motion inertial references; closed-loop command of the UAV are also
•
determine the optimum approach hosted by the shipborne computer.
System demonstrator trajectory and velocity profile Development of the system has
Sirehna, a specialist engineering and according to the target point, ship progressed through computer-based
technology group acquired by DCNS in route and environmental conditions. simulations, sub-scale testing and full-scale
early 2008, also has a capability in ship The trajectory is regularly updated demonstrations using a deck motion
motion prediction and shipboard UAV (10Hz) during the approach taking simulator also developed by Sirehna. The
recovery. Under contract to the DGA, into account actual measured latter tests, using a Yamaha R-MAX type
the company has undertaken the design, platform motions and UAV UAV, were representative of a frigate flight
development, manufacture and test position measurements; deck experiencing motions consistent with
of an automatic deck recovery system
•
transmit commands in real time to the Sea State 5 and various wave incidences.
demonstrator for a VTOL UAV. UAV flight control system to manage its First tests on board a naval platform are
The recovery system solution developed recovery trajectory. planned for early 2009. WT
SADA uses an infrared sensor to accurately track a UAV while generating flight commands to adjust the trajectory, until the vehicle is
correctly positioned.
30 Warship Technology March 2009
WT_Mar09_p29+30+31+32.indd 2 3/4/09 9:40:25 PM
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