Accession Number:

ADA202692

Title:

Selection of a Frequency Sensitive QFT (Quantitative Feedback Theory) Weighting Matrix Using the Method of Specified Outputs

Descriptive Note:

Master's thesis

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s):

Report Date:

1988-12-01

Pagination or Media Count:

112.0

Abstract:

Use of Quantitative Feedback Theory QFT on a multiple input multiple output control system requires certain mathematical properties of the plant matrix of transfer functions. In general, the plant matrix P s does not possess the necessary or desired mathematical properties for the QFT design to proceed. A frequency sensitive weighting matrix Delta s is used to transform the plant matrix P s into the equivalent plant matrix Pes that does satisfy QFT requirements. In matrix notation, the relationship between the equivalent plant, plant, and weighting matrix is Pe sPs Delta s. This thesis identifies the necessary and desired characteristics of the equivalent plant Pes for the QFT process, explains the use of the Method of Specified Outputs which generates the frequency sensitive weighting matrix Deltas, and calculates several weighting matrices for a 3-input 2-output lateral-directional model of the F-16 aircraft. For several control system failures, the mathematical structure of the failed equivalent plant matrices Pefs is examined for compliance with QFT requirements. A weighting matrix Delta s is found that produces acceptable equivalent plant matrices for failures of down to 0.01 of available control surface deflections. The use of the software packages MATRIXx and MACSYMA is explained as applied to the Method of Specified Outputs.

Subject Categories:

  • Flight Control and Instrumentation

Distribution Statement:

APPROVED FOR PUBLIC RELEASE