Flight tests provided a crucial vehicle for evaluating how well the implementation of a design worked. Safety was the principle concern.
The first step in the flight test process was to develop the capability to
switch between the manual to automatic flight control modes, using one of
the toggle controls on the RC transmitter.
Flight tests consisted of two pilots. One pilot, prepared to select the
manual mode and resume full control of the vehicle, monitored the vehicle
flying autonomously and controlled any degrees of freedom which were
not automated during the test.
A safety pilot monitored the flight and was responsible for using the ``kill''
switch if an emergency situation developed. Only the pilot and safety pilot
were allowed near the vehicle; other participants were required to stand back
at least 
ft.
As the on-board systems were developed, levels of flight autonomy were tested in a progressive manner. The altitude control loop was closed first. In this test, the flight computer regulated altitude to a commanded reference, while a pilot manually flew the other axes. After successfully demonstrating altitude control, heading control was added to the flight computer and two degree of freedom (DOF) autonomous flight was proven. Next, pitch and roll loops were added to the flight computer, demonstrating four DOF autonomy. Finally, with the incorporation of the ground-based navigation system, six DOF autonomous control was flight tested. In parallel, the disk retrieval system was evaluated using a second, manually flown helicopter until integration with the autonomous helicopter.
Information gathering was critically important for post-flight analysis. Videos of all flight tests were recorded for documentation and post flight evaluation. Furthermore, the flight computer was configured to record all measurements, state estimates, and control inputs. This flight data was analyzed to improve the dynamic models in our simulation and to tune parameters in the control algorithms.