Autopilot control board
The sensor board contains an inertial measurement unit for measurement
of the attitude, absolute and differential pressure sensors for altitude
and air speed and a low power GPS. The DsPic gives commands to the actuators,
i.e the motor and the servo motors of the control surfaces. This is
done through a servo board that also receives commands from the operator
on the ground. This board is completely independent from the processor so
that, in case of problem, the operator is able to take control of the airplane
manually. Manual control is also used for take-off, landing and during preliminary
tests in order to tune the controller. The processor is as well connected
to the three MPPTs to obtain information about the power retrieved
from the solar panels and the battery charge status. Finally, the autopilot
board weighs 80 g and it power consumption is around 1.2 W.
The user can interact with the airplane using a ground control station
(GCS) composed by a graphical user interface and a bidirectional radiomodem
for communication. The state of the airplane during flight is monitored
and a visual feedback is given with virtual instruments and a 3D
map. The edition of controller parameters in order allows tuning them during
the flight experiments and the operator can send high level commands
or modify the trajectory.
For security, all commands coming from the ground are validated by the autopilot to the GCS again. Also, in case of communication losses, abnormal attitude or GPS problems, the interface warns the user so that he can quickly act according to the problem by controlling it with the remote control.