Plant template generation of uncertain plants in quantitative feedback theory

The creation of templates for uncertain plants is an essential first step in Quantitative Feedback Theory (QFT) and other frequency domain methods. For the plants with general uncertain structure, a method to identify the critical interior points in an uncertain parameter set which map to the boundaries of plant templates is presented. It is shown that the boundaries of templates are only generated by the edges of an uncertain parameter set and those critical interior points. With the help of symbolic computation, a computational tractable procedure for generating the templates is developed. This general procedure is illustrated by a vehicle clutch systems and the longitudinal dynamics of a small aircraft where the underlying uncertain parameters perturb both plants nonlinearly.