Low-order controller design for SISO systems using coprime factors and LMI

This paper develops a low-order controller design method for linear continu ous time-invariant single-input, single;output systems requiring only the s olution of a convex optimization problem, The technique integrates several well-known results in control theory, An important step is the use of copri me factors so that based on strictly positive real functions, Feedback stab ilization using low-order controllers becomes a zero-placement problem whic h is comet. From this result, we develop algorithms to solve two optimal co ntrol problems.