[Studies in Computational Intelligence 481] Artur Babiarz, Robert Bieda, Karol Jędrasiak, Aleksander Nawrat (auth.), Aleksander Nawrat, Zygmunt Kuś (eds.) - Vision Based Systemsfor UAV Applications (2013, Sprin

Prototyping the Autonomous Flight Algorithms Using the Prepar3D® Simulator 225
(α , , ) is calculated relative to the object, not to the earth, and it is presented
in fig. 5 in a block "Relative Rotate". The mechanism of functioning of the block
"Relative Rotate" is also described by the equation (2).
(2)
where: – rotate matrix created from actual values of Euler angles α,β,,
– rotate matrix created from setpoint values of Euler angles α ,β , ,
– rotate matrix with Euler angles error α ,β , . The angles error can be
calculated from three trigonometric formulas (3).
α atan2 ,
β asin
atan2 , (3)
where: – roll angle, – pitch angle, – yaw angle.
6 Autonomous Flight Algorithm
To get a fully autonomous object, PI controllers are not enough. They are responsible
only for the stabilization, what means that the plane can fly at the required
height and setpoint orientation relative to the ground. Flying object should store in
the memory the planned route with the takeoff and landing positions. The route
consists of a sequence of points, described as a geographic coordinates LLA, the
Latitude (), Longitude () and Altitude (height above sea level, ). Each of the
commands performed during the flight must be properly interpreted and converted
to setpoints for the PI controllers.
To navigate an unmanned object, algorithm uses the transformation from the
geodetic position (LLA) to ENU coordinates (East, North, Up) [13], which are
formed from a plane tangent to the Earth's surface fixed to a specific location.
Units are converted to meters.
The presented autonomous flight algorithm consists of four partial algorithms
responsible for taking-off, landing, taking waypoints and circling.
6.1 Taking-Off and Landing Algorithm
The basic requirement for the autonomous take-off are accurate measurements of
geographical coordinates and the altitude, of start and end of the runway. Take-off
algorithm consists of only a few simple instructions. After launching the engine
algorithm maintain the orientation of the runway and it accelerate the aircraft to
the desired speed. Next, the algorithm change the setpoint pitch angle of the aircraft,
and then there are determined the ENU coordinates for the destination