Loop transfer recovery approach to H(infinity) design for the coupled mass benchmark problem

This paper presents fixed-order dynamic compensator designs for the coupled mass benchmark problem. The design technique uses a method for loop transfer recovery at the plant input to approximately recover the transfer properties of an H(infinity) controller with full state feedback. The recovery is accomplished by the unique selection of quadratic performance index weighting matrices in a standard optimal output feedback formulation for fixed-order compensation. For the benchmark control problem, two compensator designs are developed. These designs use an observer canonical form to represent the compensator dynamics. The first design addresses problem 1, where only the spring stiffness is uncertain. The second design, a solution to problem 3, provides asymptotic rejection of a sinusoidal disturbance in the presence of an uncertain spring stiffness. (Author)