The use of a new optimization criterion for discrete-time feedback controller design

We introduce a class of linear discrete-time systems called "super stable". For the SISO case this means that the absolute value of the constant term of the characteristic polynomial is greater than the sum of absolute values of all other coefficients, while super stable MIMO systems have a state matrix with l/sub 1/ norm less than one. Such systems have many special features. Within the framework of these systems we can, using linear programming, design fixed-order controllers. We also address robustness issues, including robust performance for transfer functions with coprime factor uncertainty bounded in l/sub 1/ norm.