Design of multirate digital control systems with semidefinite programming

A computer aided design method for linear multirate digital control systems is presented in this paper. The design problem is formulated on the infinity norm of signals and the induced l₁-system norm. An upper bound for the l₁-system norm leading to matrix inequalities is the basis of the design procedure. It is a characteristic feature of the method that the controller is attained by repeatedly solving small size convex optimization problems. Considering an example it turns out, that multirate digital controllers can help to overcome the well known problem of inflating controller order in induced l₁-control