Robust Controller Design for Uncertain Dynamic Systems Using Approximate Models. Part 1: The Single-Input/Single-Output Case

摘要

Controller design for continuous and discrete systems whose models are unknown or highly complex is discussed. These designs are frequently based on the use of a simple, approximate and, very often, rough-and-ready model. In such circumstances it is vital to be able to quantify the degree of uncertainty to be expected from the use of such a model for prediction of closed loop characteristics. It is shown how classical frequency domain design techniques can be extended to incorporate information deduced from the observed differences between open loop plant and approximate model step response to quantify this uncertainty and, in particular, to guarantee closed loop stability and tracking of step demands. A modification of this analysis also yields the possibility of bounding the error in prediction of closed loop transient performance. The approaches are all graphical in nature and can be easily implemented in an interactive computer aided design mode.