Comprehensive System Identification of Ducted Fan UAVs - Cal Poly

The identified state-space model yielded 7 eigenvalues. Two of these werecomplex pairs, and three real. These 7 eigenvalues depict 5 modes. Mode #1 is the yawmode which was modeled with no yaw damping, thus the value of 1 for the yaw rate state(r). Mode #2 is associated with the 2 nd order periodic denominator term in the hoveringcubic because of the high values for the lateral velocity (v) and roll rate (p) states. This isa low frequency unstable mode. Likewise, Mode #5 is from the 2 nd order term inlongitudinal hovering cubic. This is seen by the larger eigenvectors for the states oflongitudinal velocity (u) and pitch rate (q). The remaining eigenvectors identify the 1 storder, aperiodic subsidence modes for roll (Mode #3) and pitch (Mode #4). Theseeigenvalues are very close to the modes of the transfer function models (Equations 1-3).The excellent agreement between the flight data and model can be seen in thefollowing frequency responses comparing the parametric state space model and the actualflight test data.- 25 -