Control Loop

Figure 1: 

After some unsuccessful tries to control the the quadcopter with a simple PID-Controller, we recognized that this approach is much to slow. With the help of Dipl.-Ing. Dr. Martin Staudecker, we ended up
in a 2-Layer cascading structure. The reference values coming from the steering, are the base-power and the angles around the pitch-, roll- and yaw-axis. For the decoupling
of the actuating variables we used the equations shown in Figures 3 and 4.

Figure 2: 

Variables and their meaning

Variables and their meaning

Variable Description
T base-thrust to control the height
tau_a, tau_b, tau_c moments around the three axis
omega_1,_2,_3,_4 angular rates of the 4 engines
k thrust constant, correlation between motor speed and thrust (measured manually)
l difference between the air screws and the center of gravity
b air drag coefficient, chosen with 1
phi angles around the three axis (output of the kalman-filter)
phi/dt angular rates, directly from the gyroscope and not filtered

Figure 3: 
Figure 4: