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

consistency by reconstructing responses for various signals based on kinematic laws of motion.
Examples of this type of analysis can be found in Chapter 4.
The arithmetic function uses the screen interface from the main programs but only has two
screens. Thus the conversion to command-line interface was reasonably straightforward.
2.5 Parametric Modeling – NAVFIT, DERIVID, VERIFY
The three remaining main programs of CIFER ® will be covered in less detail as this project does
not involve them. It is important to note their use as this constitutes a major portion of CIFER ® ’s
potential and the direction that future work on modernizing the interface will take.
NAVFIT allows users to fit a transfer function to a single frequency response. The interface uses
a cost function to give the user an indication of how closely a particular fit matches the response
data. The user specifies the order of the transfer function desired and then the program iterates to
find an optimum fit.
The interface used by NAVFIT is similar to the RMS and bandwidth utilities except it has many
more input options and more loops at certain segments. Additionally, it was built up on code that
was originally created by McDonnell Douglas Aircraft outside of NASA. Thus, it would be
particularly challenging to adapt to a command-line format. This was one major factor for not
including NAVFIT within the scope of this project.
DERIVID constructs a state-space system based on a series of related frequency responses. It
generates the appropriate control derivatives for the coefficient matrices of a state-space system.
This is a very powerful ability as it enables the creation or validation of math models for
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