An Educational Environment for the Teaching of Quantitative Feedback Theory

Abstract During the past few years there has developed a widespread interest in Horowitz’s Quantitative Feedback Theory (QFT) because of its potential for solving complex real-world control problems. In particular, QFT focuses on achieving the desired system performance despite plant models with parameter uncertainly and additive disturbances. The design of a QFT robust controller requires the formulation of quantitative factors representing acceptable input-output models, a set of plant models due to parameter uncertainity and graphical composition. To accomplished this task requires considerable numerical and symbolic manipulation and therefore implies that an extensive educational environment be provided. The intent of this paper is to present such an educational environment in which extensive student design projects can be accomplished. Both the multi-input single-output (MISO) and the multiple-input multiple-output (MIMO) models are depicted in the classroom along with discussion of various CAD packages. The QFT MIMO controller development is approached by converting the MIMO model into a number of MISO models. Both the continuous and discrete QFT design procedures are elements of the educational program. Discussion of appropriate prerequisites for the various models is included in the paper as an integral element of a control engineer’s education. The major educational emphasis is on the development of a student’s ability to apply the unified QFT method. Various aspects of the QFT educational CAD capabilities exist under various computer operating system environments.