Structured servo controller design using output-feedback

The authors propose a general linear quadratic tracker formulation using output-feedback that allows the use of a dynamic compensator of prescribed structure. The performance index is of a general form that covers various design objectives and includes time weighting of the form t^k, as well as steady-state error weighting. Necessary conditions for the optimal control gains are found. The correct initial conditions for the optimal design are not uniformly distributed as usually assumed, but have specific values as derived here