CIFER®-MATLAB Interfaces: Development and ... - Cal Poly

Figure 4.14: Roll Angle to Rate Comparison
Figure 4.15: Pitch Angle to Rate Comparison
The next check using the simulation data was performed for Equations 4.6 through 4.8.
Frequency response arithmetic was used to combine the on-axis responses of rates and attitudes to
calculate the velocity perturbations in the frequency domain from the appropriate frequency
responses. These were compared to the corresponding velocity perturbation responses that were
initially reconstructed in the FRESPID program using the same math on the time history data.
Equation 4.11 shows an example of how the frequency responses were combined using
arithmetic.
u
δ
ele
=
a
δ
x
ele
1 q
− g
s δ
ele
[4.11]
These comparisons are shown in Figure 4.16 through Figure 4.18 using a forward velocity of 65
knots. Both methods of calculation overlay nearly precisely, which makes sense as both plots are
based on the same data, one created straight from the time domain and one built through
frequency response arithmetic. Even in regions of low coherence, both calculations include the
same errors and thus arrive at the same answers. The coherence plots vary due to a convention in
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