Assistance system facilitates formation flight of manned and unmanned aircraft
Such a formation always consists of at least two aircraft forming a team. For this to be possible at all, the participating aircraft, both manned and unmanned, must in principle be able to fly in formation. As part of its research work, DLR investigated three types of formation flight: waypoint mode, relative navigation and corridor mode.
Before the real flight tests could take place with an unmanned helicopter of the DLR-ARTIS family (Autonomous Rotorcraft Testbed for Intelligent Systems) and the DLR research helicopter, a modified Eurocopter EC135, the system had to be tested in a simulator. DLR pilots tested and evaluated the assistance system and the three different modes in the helicopter simulator of the AVES simulator centre (Air Vehicle Simulator).
The pairing mode is the beginning of every joint team flight. In this mode, the initial state for the formation flight is created: The aircraft approach each other and form a stable formation. Once this is done, the pilot can switch to waypoint mode, for example. In this mode, the UAS (Unmanned Aircraft System) flies an exact path using predefined waypoints. The manned helicopter follows it manually, controlled by the pilot, analogous to a formation flight of two manned helicopters.
Another possibility is relative navigation. Here the unmanned helicopter is positioned relative to the manned helicopter. The UAS automatically flies ahead, but adapts its flight behaviour to that of the manned helicopter and must hold the position independently. The purpose of relative navigation is to make it possible to fly in close formation. If one flies such a close formation without an assistance system, this means a high workload for the pilots, since the position within the formation must always be maintained manually and visually controlled. The assistance system developed by the scientists performs these tasks by the UAS holding the position by itself using an algorithm and the UAS position is additionally represented by an anti-collision display.
The third scenario is the so-called corridor mode. The UAS flies a previously calculated flight path within a corridor and the manned helicopter follows it at a safe distance. The path is not as strictly defined as in waypoint mode. If manned and unmanned helicopters come too close in this scenario, the unmanned aircraft is allowed to evade freely within the specified corridor. Thus the flight movements can deviate also accordingly from each other. The manned helicopter also has the say here. In order to keep the workload for the pilots as low as possible, the UAS must automatically remain within the visible range of the manned helicopter. If this is not possible, the system automatically switches to relative navigation mode. Particularly in labour-intensive situations, these modes are intended to significantly reduce the workload due to the cooperative behaviour of the UAS. In addition, the UAS is able to automatically terminate the formation flight in the event of a critical situation.
After the simulations, nothing stood in the way of real flight tests at Magdeburg-Cochstedt Airport. The unmanned superARTIS and the DLR research helicopter FHS flew in several tests two of the three modes tested in the simulator: waypoint and corridor mode. According to DLR, the testing went smoothly; the next step is a broader testing campaign with external pilots. DLR sees applications for the formation flights coordinated by an assistance system, for example, in reconnaissance flights following natural disasters.
More information: https://www.DLR.de/
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