Off-line Controller Design

In Chapter 2, the parameterization of a stabilizing controller K (Q) for a linear plant in terms of a stable (matrix) transfer function Q is discussed. It is shown that if Q spans the class of all stable proper (matrix) transfer functions, the entire class of stabilizing controllers for the plant is spanned. It can make sense in a controller design to optimize engineering objectives over this class, rather than over the class of all possible controllers, which of course includes the undesirable subclass of destabilizing controllers. In this chapter, we present various off-line optimal controller designs that, in addition to stabilization of the nominal plant will also allow the controller to track some reference signals and/or reject various classes of disturbances in some optimal fashion.