Task 2

Switching Lines

Nur Harell, Matthew Berk

In the following, Team SPAERO presents its approach for switching between linesand present two independent experimental flights to prove its effectiveness. The control system logic is the same as in Task 1. For switching between lines, new waypoints are given to the algorithm to form the new line. As discussed with the instructors team during the progress report on 05/09/2015, two 45 degree turns are presented.

Test Flight 1:

During the first experiment, the plane follows a line to the southwest and then switches to a line pointing directly west. The angle between the lines is hence 45 degrees. The experimental data is presented in the following.

As can be seen from the plot, the airplane goes towards the first line as soon as auto mode is switched on. As soon as the plane reaches the line, it turns and stabilizes to follow it. It is to be noted that strong wind from the north-east is blowing. This explains the steady-state error. Once reaching a distance of 5 m from the intersection of both lines, the plane turns and starts following the second line.

As can be seen from the plot above, the airspeed of 9 m/s is held during the flight. The increase at around 143 seconds into the flight is due to the sharp turn when switching into the auto mode. The maximum desired bank angle is exceeded once during that sharp turn. The plane is automatically stabilized quickly and starts following the first line. The switch between the lines occurs without any extraordinary speed losses or bank/pitch angles.

As in the previous experiments, the desired altitude was set to 70 m. The auto mode was switched on while the plane was very low which explains why the aircraft is gaining altitude. As mentioned before, the altitude control is currently not aggressive enough and will be fixed for future flights.

The commanded control inputs stay within the desired boundaries at any time. The introduced clipping prevents any of the values to reach unrealistic ones.

The deviation from both lines is plotted versus time. As soon as the auto mode is switched on, y for the first line is reduced significantly and quickly. Once the waypoint is reached at about 157 seconds and the airplane starts to follow the second line, the y value for the second line is dropping. Mind the steady state error due to the strong wind.

Test Flight 2:

During the second experiment, the plane follows a line pointing directly to the west and then switches to a line pointing to the northwest. The angle between the lines is hence 45 degrees. The experimental data is presented in the following.

As can be seen from the plot, the airplane is following the first line at the beginning. Once reaching a distance of 5 m from the intersection of both lines, the plane turns and starts following the second line.

An airspeed of 12 m/s is desired during the flight. The steady state error is due to the sub-optimal trims. More flight experiments will lead to better estimates of the trim values. As in the first experiment, the switch between the lines occurs without any extraordinary speed losses or bank/pitch angles.

As in the previous experiments, the desired altitude was set to 70 m. The auto mode was switched on while the plane was very high which explains why the aircraft is loosing altitude. As mentioned before, the altitude Control is currently not aggressive enough and will be fixed for future flights.

The commanded control inputs stay within the desired boundaries at any time. The introduced clipping prevents any of the values to reach unrealistic ones

The deviation from both lines is plotted versus time. As soon as the auto mode is switched on, y for the first line is reduced significantly and quickly. Once the waypoint is reached at about 263 seconds and the airplane starts to follow the second line, the y value for the second line is dropping.