The two main responsibilities of the Stability and Control sub-team are to conduct the complete analysis and study of both the “static” and “dynamic” stability of the aircraft.
Theoretically, the Static Stability is referred to the design of the control surfaces and the tail of the aircraft through an iterative process, in order to identify their optimal configuration and size. The study for the Dynamic Stability of the aerial vehicle begins after the layout of the airplane is defined and it is found to be statically stable. The members of this sub-team have created multiple MATLAB scripts in order to calculate the span, chord, deflection and position of each one of them. This process considers the static margin, the needed aerodynamic constants and the relative position of the airplane components, to predict the forces and moments that are applied to the aircraft. Furthermore, Stability&Control calculate with the help of the Aerodynamics sub-team the stability derivatives,having the layout of the aircraft, both non – dimensional and dimensional.
Stability&Control Sub-Team interests are expanding in the field of data acquisition concerning critical state variables of the airplane comparing them with the theoretical results. The Stability&Control sub-team undertake the development of a system to provide real-time feedback during the flight. It is composed of accelerometers, gyroscopes, magnetometers, GPS, altimeters and telemeters to record the corresponding parameters. Specifically, a GPS neo 6m, MPU9250 9-axis motion measurement unit, MPL3115A2 as barometer, SX1278 telemetry chip and a SD card storage, two microcontrollers: the stm32f103c8 and the AtMega385, are used. The first obstacle that is encountered, is the combination of all the different communication protocols that each device follows into one system in order to work in harmony and precision. However, the most challenging task for Stability&Control sub-team is not only to gather these data, but also to remove the stochastic noise from all the measurements, due both to the external disturbances and the nature of the sensors. To overcome this problem, the members of this sub-team have created two sensor fusion algorithms, a Complementary and a Kalman filter.
As the motor constitutes one the most crucial parts of the aircraft, a close study of its behavior is of paramount concern. Stability&Control have created a system, which is composed by a special motor mount, designed in SolidWorks, and a PCB design containing all the sensor required to measure the important variables of the motor such as internal resistance, thrust, torque, rpm and power consumption. The PCD is designed in Eagle and contains sensors such as load cells, speedometers and voltage sensors. An Arduino nano microcontroller is used as brain that processed and recorded the data.