Feedforward Control Design for Multi-input Multi-output Plants by Model Matching Using Inner–Outer Factorization

We study the model matching problem of determining a feedforward controller for a multi-input–multi-output (MIMO) linear time-invariant plant and a reference model. In this article, we propose a model matching method for the outer of the plant square transfer function, in which the singular values of the frequency response of the control system are sufficiently close to those of the reference model. The model matching method is provided for both continuous-time and discrete-time plants. The discrete-time controller is an extension of the zero-magnitude-error tracking controller to MIMO plants. The method is compared with the model matching methods based on <inline-formula><tex-math notation="LaTeX">$H_{2}$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$H_\infty$</tex-math></inline-formula> control theory for continuous-time plants.