Hi @osama
If you are referring to the original QFT Toolbox developed by Craig Borghesani, the founder of Terasoft, and previously available in MATLAB 5.0 (1996), it was reacquired by Terasoft in 2000. Consequently, it was no longer available after MATLAB 6.0 (R12). Nevertheless, the QFT Toolbox is still offered by Terasoft, with the lowest price for a single academic license being $225.00. In fact, version 2.0 is available, but it only supports MATLAB versions 5.3 to 7.14 (R2012a).
QFT is fundamentally concerned with loop shaping using the Nichols chart to achieve robust control design in the presence of uncertainties in the plant model. If you are already familiar with frequency-domain control design techniques, learning QFT should be more efficient than starting from scratch. An open-source QFT Toolbox called Open Qsyn is available, and you may want to give it a try.
